Inventions and Inventors Volume 1 - Online Public Access Catalog

Inventions
and
Inventors

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MAGILL’S CHOICE
Inventions
and
Inventors
Volume 1
Abortion pill — Laminated glass
1 – 458
edited by
Roger Smith
Salem Press, Inc.
Pasadena, California Hackensack, New Jersey

Copyright © 2002, by Salem Press, Inc.
All rights in this book are reserved. No part of this work may be
used or reproduced in any manner whatsoever or transmitted
in any form or by any means, electronic or mechanical, including
photocopy, recording, or any information storage and retrieval
system, without written permission from the copyright
owner except in the case of brief quotations embodied in critical
articles and reviews. For information address the publisher, Salem
Press, Inc., P.O. Box 50062, Pasadena, California 91115.
Essays originally appeared in Twentieth Century: Great Events
(1992, 1996), Twentieth Century: Great Scientific Achievements (1994),
and Great Events from History II: Business and Commerce Series
(1994). New material has been added.
∞ The paper used in these volumes conforms to the American
National Standard for Permanence of Paper for Printed Library
Materials, Z39.48-1992 (R1997).
Library of Congress Cataloging-in-Publication Data
Inventions and inventors / edited by Roger Smith
p.cm. — (Magill’s choice)
Includes bibliographical reference and index
ISBN 1-58765-016-9 (set : alk. paper) — ISBN 1-58765-017-7
(vol 1 : alk. paper) — ISBN 1-58765-018-5 (vol 2. : alk. paper)
1. Inventions—History—20th century—Encyclopedias. 2. Inventors—Biography—Encyclopedias.
I. Smith, Roger, 1953- .
II. Series.
T20 .I59 2001
609—dc21 2001049412
printed in the united states of america

Table of Contents
Table of Contents
Publisher’s Note . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix
Editor’s Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
Abortion pill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Airplane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Alkaline storage battery . . . . . . . . . . . . . . . . . . . . . . . 11
Ammonia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Amniocentesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Antibacterial drugs . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Apple II computer. . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Aqualung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Artificial blood . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Artificial chromosome . . . . . . . . . . . . . . . . . . . . . . . . 41
Artificial heart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Artificial hormone. . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Artificial insemination . . . . . . . . . . . . . . . . . . . . . . . . 54
Artificial kidney . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Artificial satellite . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Aspartame . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Assembly line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Atomic bomb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
Atomic clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Atomic-powered ship. . . . . . . . . . . . . . . . . . . . . . . . . 84
Autochrome plate . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
BASIC programming language . . . . . . . . . . . . . . . . . . . 92
Bathyscaphe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Bathysphere . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
BINAC computer . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Birth control pill . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
Blood transfusion . . . . . . . . . . . . . . . . . . . . . . . . . . 113
Breeder reactor . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
Broadcaster guitar . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Brownie camera . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
Bubble memory . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
v

Table of Contents
Bullet train . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
Buna rubber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
CAD/CAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
Carbon dating . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
Cassette recording . . . . . . . . . . . . . . . . . . . . . . . . . . 163
CAT scanner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
Cell phone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172
Cloning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
Cloud seeding . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
COBOL computer language . . . . . . . . . . . . . . . . . . . . 187
Color film . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192
Color television . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
Colossus computer . . . . . . . . . . . . . . . . . . . . . . . . . 200
Communications satellite . . . . . . . . . . . . . . . . . . . . . . 204
Community antenna television . . . . . . . . . . . . . . . . . . 208
Compact disc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
Compressed-air-accumulating power plant . . . . . . . . . . . 225
Computer chips . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
Contact lenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
Coronary artery bypass surgery . . . . . . . . . . . . . . . . . . 240
Cruise missile . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244
Cyclamate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248
Cyclotron . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252
Diesel locomotive . . . . . . . . . . . . . . . . . . . . . . . . . . 257
Differential analyzer. . . . . . . . . . . . . . . . . . . . . . . . . 262
Dirigible. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267
Disposable razor . . . . . . . . . . . . . . . . . . . . . . . . . . . 272
Dolby noise reduction . . . . . . . . . . . . . . . . . . . . . . . . 279
Electric clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284
Electric refrigerator . . . . . . . . . . . . . . . . . . . . . . . . . 289
Electrocardiogram . . . . . . . . . . . . . . . . . . . . . . . . . . 293
Electroencephalogram. . . . . . . . . . . . . . . . . . . . . . . . 298
Electron microscope . . . . . . . . . . . . . . . . . . . . . . . . . 302
Electronic synthesizer . . . . . . . . . . . . . . . . . . . . . . . . 307
ENIAC computer . . . . . . . . . . . . . . . . . . . . . . . . . . 312
vi

Table of Contents
Fax machine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316
Fiber-optics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 320
Field ion microscope. . . . . . . . . . . . . . . . . . . . . . . . . 325
Floppy disk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 330
Fluorescent lighting . . . . . . . . . . . . . . . . . . . . . . . . . 335
FM radio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 339
Food freezing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 343
FORTRAN programming language . . . . . . . . . . . . . . . . 347
Freeze-drying. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 351
Fuel cell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355
Gas-electric car . . . . . . . . . . . . . . . . . . . . . . . . . . . . 360
Geiger counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . 365
Genetic “fingerprinting” . . . . . . . . . . . . . . . . . . . . . . 370
Genetically engineered insulin . . . . . . . . . . . . . . . . . . . 374
Geothermal power. . . . . . . . . . . . . . . . . . . . . . . . . . 378
Gyrocompass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 382
Hard disk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 386
Hearing aid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 390
Heart-lung machine . . . . . . . . . . . . . . . . . . . . . . . . . 394
Heat pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 398
Holography. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 402
Hovercraft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 407
Hydrogen bomb . . . . . . . . . . . . . . . . . . . . . . . . . . . 412
IBM Model 1401 computer . . . . . . . . . . . . . . . . . . . . . 417
In vitro plant culture. . . . . . . . . . . . . . . . . . . . . . . . . 421
Infrared photography . . . . . . . . . . . . . . . . . . . . . . . . 425
Instant photography. . . . . . . . . . . . . . . . . . . . . . . . . 430
Interchangeable parts . . . . . . . . . . . . . . . . . . . . . . . . 434
Internal combustion engine. . . . . . . . . . . . . . . . . . . . . 442
The Internet. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 446
Iron lung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 451
Laminated glass . . . . . . . . . . . . . . . . . . . . . . . . . . . 454
vii

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Publisher’s Note
Publisher’s Note
To many people, the word “invention” brings to mind cleverly contrived
gadgets and devices, such as safety pins, zippers, typewriters,
and telephones—all of which have fascinating stories of invention
behind them. However, the word actually has a much broader meaning,
one that goes back to the Latin word invenire, for “to come upon.”
In its broad sense, an invention can be any tangible device or contrivance,
or even a process, that is brought into being by human imagination.
It is in this broad sense that the term is used in Inventions and Inventors,
the latest contribution to the Magill’s Choice reference books.
This two-volume set contains articles on 195 twentieth century
inventions, which span the full range of human imagination—from
simple gadgets, such as disposable razors, to unimaginably complex
medical breakthroughs, such as genetically engineered insulin.
This set is not an encyclopedic catalog of the past century’s greatest
inventions but rather a selective survey of noteworthy breakthroughs
in the widest possible variety of fields.
A combination of several features sets Inventions and Inventors
apart from other reference works on this subject: the diversity of its
subject matter, the depth of its individual articles, and its emphasis
on the people behind the inventions. The range of subjects covered
here is unusually wide. In addition to articles on what might be considered
“classic” inventions—such as airplanes, television, and satellites—the
set has articles on inventions in fields as diverse as agriculture,
biology, chemistry, computer science, consumer products,
drugs and vaccines, energy, engineering, food science, genetic engineering,
medical procedures, music, photography, physics, synthetics,
transportation, and weapons technology.
Most of this set’s essays appeared earlier in Twentieth Century:
Great Events (1992, 1996) and Twentieth Century: Great Scientific
Achievements (1994). Its longest essays are taken from Great Events
from History II: Business and Commerce Series (1994). Information in
the articles has been updated, and completely new bibliographical
notes have been added to all of them. Half the essays also have original
sidebars on people behind the inventions.
ix

Publisher’s Note
At least one thousand words in length, each essay opens with a
brief summary of the invention and its significance, followed by an
annotated list of important personages behind it—including scientists,
engineers, technicians, and entrepreneurs. The essay then examines
the background to the invention, its process of discovery
and innovation, and its impact on the world. Half the articles have
entirely new sidebars on individuals who played important roles in
the inventions’ development and promotion.
Users can find topics by using any of several different methods.
Articles are alphabetically arranged under their titles, which use the
names of the inventions themselves, such as “Abortion pill,” “Airplane,”
“Alkaline storage battery,” “Ammonia,” and “Amniocentesis.”
Many inventions are known by more than one name, however,
and users may find what they are looking for in the general index,
which lists topics under multiple terms.
Several systems of cross-referencing direct users to articles of interest.
Appended to every essay is a list of articles on related or similar
inventions. Further help in can be found in appendices at the end
of volume two. The first, a Time Line, lists essay topics chronologically,
by the years in which the inventions were first made. The second,
Topics by Category list, organizes essay topics under broader
headings, with most topics appearing under at least two category
headings. Allowing for the many topics counted more than once,
these categories include Consumer products (36 essays), Electronics
(28), Communications (27), Medicine (25), Measurement and detection
(24), Computer science (23), Home products (20), Materials
(18), Medical procedures (17), Synthetics (17), Photography (16), Energy
(16), Engineering (16), Physics (13), Food science (13), Drugs
and vaccines (13), Transportation (11), Weapons technology (11),
Genetic engineering (11), Aviation and space (10), Biology (9),
Chemistry (9), Exploration (8), Music (7), Earth science (6), Manufacturing
(6), and Agriculture (5).
More than one hundred scholars wrote the original articles used
in these volumes. Because their names did not appear with their articles
in the Twentieth Century sets, we cannot, unfortunately, list
them here. However, we extend our thanks for their contributions.
We also are indebted to Roger Smith for his help in assembling the
topic list and in writing all the biographical sidebars.
x

Editor’s Foreword
The articles in Inventions and Inventors recount the birth and growth
of important components in the technology of the twentieth centuries.
They concern inventions ranging from processes, methods,
sensors, and tests to appliances, tools, machinery, vehicles, electronics,
and materials. To explain these various inventions, the essays
deal with principles of physics, chemistry, engineering, biology, and
computers—all intended for general readers. From complex devices,
such as electron microscopes, and phenomena difficult to define,
such as the Internet, to things so familiar that they are seldom
thought of as having individual histories at all, such as Pyrex glass
and Velcro, all the inventions described here increased the richness
of technological life. Some of these inventions, such as the rotarydial
telephone, have passed out of common use, at least in the
United States and Europe, while others, such as the computer, are
now so heavily relied upon that mass technological culture could
scarcely exist without them. Each article, then, is at the same time a
historical sketch and technical explanation of an invention, written
to inform and, I hope, intrigue.
Brief biographical sidebars accompany half the articles. The
sidebars outline the lives of people who are in some way responsible
for the inventions discussed: the original inventor, a person who
makes important refinements, an entrepreneur, or even a social crusader
who fostered acceptance for a controversial invention, as Margaret
Sanger did for the birth control pill. These little biographies,
although offering only basic information, call forth the personal
struggles behind inventions. And that is a facet to inventions that
needs emphasizing, because it shows that technology, which can
seem bewilderingly impersonal and complex, is always rooted in
human need and desire.
Roger Smith
Portland, Oregon
xi

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Inventions
and
Inventors

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Inventions
and
Inventors

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MAGILL’S CHOICE
Inventions
and
Inventors
Volume 2
Laser — Yellow fever vaccine
Index
459 – 936
edited by
Roger Smith
Salem Press, Inc.
Pasadena, California Hackensack, New Jersey

Copyright © 2002, by Salem Press, Inc.
All rights in this book are reserved. No part of this work may be
used or reproduced in any manner whatsoever or transmitted
in any form or by any means, electronic or mechanical, including
photocopy, recording, or any information storage and retrieval
system, without written permission from the copyright
owner except in the case of brief quotations embodied in critical
articles and reviews. For information address the publisher, Salem
Press, Inc., P.O. Box 50062, Pasadena, California 91115.
Essays originally appeared in Twentieth Century: Great Events
(1992, 1996), Twentieth Century: Great Scientific Achievements (1994),
and Great Events from History II: Business and Commerce Series
(1994). New material has been added.
∞ The paper used in these volumes conforms to the American
National Standard for Permanence of Paper for Printed Library
Materials, Z39.48-1992 (R1997).
Library of Congress Cataloging-in-Publication Data
Inventions and inventors / edited by Roger Smith
p.cm. — (Magill’s choice)
Includes bibliographical reference and index
ISBN 1-58765-016-9 (set : alk. paper) — ISBN 1-58765-017-7
(vol 1 : alk. paper) — ISBN 1-58765-018-5 (vol 2. : alk. paper)
1. Inventions—History—20th century—Encyclopedias. 2. Inventors—Biography—Encyclopedias.
I. Smith, Roger, 1953- .
II. Series.
T20 .I59 2001
609—dc21 2001049412
printed in the united states of america

Table of Contents
Table of Contents
Laser. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 459
Laser-diode recording process . . . . . . . . . . . . . . . . . . . 464
Laser eye surgery . . . . . . . . . . . . . . . . . . . . . . . . . . 468
Laser vaporization . . . . . . . . . . . . . . . . . . . . . . . . . . 472
Long-distance radiotelephony . . . . . . . . . . . . . . . . . . . 477
Long-distance telephone . . . . . . . . . . . . . . . . . . . . . . 482
Mammography. . . . . . . . . . . . . . . . . . . . . . . . . . . . 486
Mark I calculator . . . . . . . . . . . . . . . . . . . . . . . . . . . 490
Mass spectrograph. . . . . . . . . . . . . . . . . . . . . . . . . . 494
Memory metal . . . . . . . . . . . . . . . . . . . . . . . . . . . . 498
Microwave cooking . . . . . . . . . . . . . . . . . . . . . . . . . 502
Neoprene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 507
Neutrino detector . . . . . . . . . . . . . . . . . . . . . . . . . . 511
Nuclear magnetic resonance . . . . . . . . . . . . . . . . . . . . 516
Nuclear power plant. . . . . . . . . . . . . . . . . . . . . . . . . 520
Nuclear reactor. . . . . . . . . . . . . . . . . . . . . . . . . . . . 525
Nylon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 529
Oil-well drill bit . . . . . . . . . . . . . . . . . . . . . . . . . . . 533
Optical disk. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 537
Orlon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 541
Pacemaker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 545
Pap test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 549
Penicillin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 553
Personal computer. . . . . . . . . . . . . . . . . . . . . . . . . . 558
Photoelectric cell . . . . . . . . . . . . . . . . . . . . . . . . . . . 562
Photovoltaic cell . . . . . . . . . . . . . . . . . . . . . . . . . . . 567
Plastic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 571
Pocket calculator . . . . . . . . . . . . . . . . . . . . . . . . . . . 576
Polio vaccine (Sabin). . . . . . . . . . . . . . . . . . . . . . . . . 581
Polio vaccine (Salk) . . . . . . . . . . . . . . . . . . . . . . . . . 585
Polyester . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 589
xix

Table of Contents
Polyethylene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 593
Polystyrene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 597
Propeller-coordinated machine gun . . . . . . . . . . . . . . . . 601
Pyrex glass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 606
Radar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 611
Radio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 616
Radio crystal sets . . . . . . . . . . . . . . . . . . . . . . . . . . 621
Radio interferometer . . . . . . . . . . . . . . . . . . . . . . . . 625
Refrigerant gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . 630
Reserpine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 634
Rice and wheat strains . . . . . . . . . . . . . . . . . . . . . . . 638
Richter scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 645
Robot (household) . . . . . . . . . . . . . . . . . . . . . . . . . . 650
Robot (industrial) . . . . . . . . . . . . . . . . . . . . . . . . . . 654
Rocket . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 658
Rotary dial telephone . . . . . . . . . . . . . . . . . . . . . . . . 663
SAINT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 668
Salvarsan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 673
Scanning tunneling microscope . . . . . . . . . . . . . . . . . . 678
Silicones. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 683
Solar thermal engine. . . . . . . . . . . . . . . . . . . . . . . . . 687
Sonar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 692
Stealth aircraft . . . . . . . . . . . . . . . . . . . . . . . . . . . . 697
Steelmaking process . . . . . . . . . . . . . . . . . . . . . . . . . 701
Supercomputer. . . . . . . . . . . . . . . . . . . . . . . . . . . . 709
Supersonic passenger plane . . . . . . . . . . . . . . . . . . . . 714
Synchrocyclotron . . . . . . . . . . . . . . . . . . . . . . . . . . 720
Synthetic amino acid . . . . . . . . . . . . . . . . . . . . . . . . 724
Synthetic DNA . . . . . . . . . . . . . . . . . . . . . . . . . . . . 729
Synthetic RNA . . . . . . . . . . . . . . . . . . . . . . . . . . . . 733
Syphilis test. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 737
Talking motion pictures . . . . . . . . . . . . . . . . . . . . . . . 741
Teflon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 746
Telephone switching. . . . . . . . . . . . . . . . . . . . . . . . . 751
Television . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 756
Tevatron accelerator . . . . . . . . . . . . . . . . . . . . . . . . . 761
xx

Table of Contents
Thermal cracking process . . . . . . . . . . . . . . . . . . . . . . 765
Tidal power plant . . . . . . . . . . . . . . . . . . . . . . . . . . 770
Touch-tone telephone . . . . . . . . . . . . . . . . . . . . . . . . 774
Transistor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 778
Transistor radio . . . . . . . . . . . . . . . . . . . . . . . . . . . 786
Tuberculosis vaccine. . . . . . . . . . . . . . . . . . . . . . . . . 791
Tungsten filament . . . . . . . . . . . . . . . . . . . . . . . . . . 795
Tupperware. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 799
Turbojet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 807
Typhus vaccine . . . . . . . . . . . . . . . . . . . . . . . . . . . . 811
Ultracentrifuge . . . . . . . . . . . . . . . . . . . . . . . . . . . . 815
Ultramicroscope . . . . . . . . . . . . . . . . . . . . . . . . . . . 819
Ultrasound . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 823
UNIVAC computer . . . . . . . . . . . . . . . . . . . . . . . . . 828
Vacuum cleaner . . . . . . . . . . . . . . . . . . . . . . . . . . . 832
Vacuum tube . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 837
Vat dye . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 842
Velcro . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 846
Vending machine slug rejector . . . . . . . . . . . . . . . . . . . 850
Videocassette recorder . . . . . . . . . . . . . . . . . . . . . . . 857
Virtual machine . . . . . . . . . . . . . . . . . . . . . . . . . . . 861
Virtual reality. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 866
V-2 rocket . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 871
Walkman cassette player . . . . . . . . . . . . . . . . . . . . . . 875
Washing machine . . . . . . . . . . . . . . . . . . . . . . . . . . 883
Weather satellite . . . . . . . . . . . . . . . . . . . . . . . . . . . 887
Xerography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 891
X-ray crystallography . . . . . . . . . . . . . . . . . . . . . . . . 896
X-ray image intensifier . . . . . . . . . . . . . . . . . . . . . . . 901
Yellow fever vaccine . . . . . . . . . . . . . . . . . . . . . . . . . 905
Time Line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 909
Topics by Category . . . . . . . . . . . . . . . . . . . . . . . . . 915
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 923
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Inventions
and
Inventors

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Abortion pill
Abortion pill
The invention: RU-486 was the first commercially available drug
that prevented fertilized eggs from implanting themselves in the
walls of women’s uteruses.
The people behind the invention:
Étienne-Émile Baulieu (1926- ), a French biochemist and
endocrinologist
Georges Teutsch, a French chemist
Alain Bélanger, a French chemist
Daniel Philibert, a French physicist and pharmacologist
Developing and Testing
In 1980, Alain Bélanger, a research chemist, was working with
Georges Teutsch at Roussel Uclaf, a French pharmaceutical company.
Teutsch and Bélanger were interested in understanding how
changes in steroids affect the chemicals’ ability to bind to their steroid
receptors. (Receptors are molecules on cells that can bind with
certain chemical substances such as hormones. Receptors therefore
act as connecting links to promote or prevent specific bodily activities
or processes.) Bélanger synthesized several steroids that bonded
to steroid receptors. Among these steroids was a compound that
came to be called “RU-486.”
Another member of the research project, Daniel Philibert, found
that RU-486 blocked the activities of progesterone by binding tightly
to the progesterone receptor. Progesterone is a naturally occurring
steroid hormone that prepares the wall of the uterus to accept a fertilized
egg. Once this is done, the egg can become implanted and
can begin to develop. The hormone also prevents the muscles of the
uterus from contracting, which might cause the uterus to reject the
egg. Therefore RU-486, by acting as a kind of shield between hormone
and receptor, essentially stopped the progesterone from doing
its job.
At the time, Teutsch’s group did not consider that RU-486 might
be useful for deliberately interrupting human pregnancy. It was
1

2 / Abortion pill
Étienne-Émile Baulieu, a biochemist and endocrinologist and a consultant
for Roussel Uclaf, who made this connection. He persuaded
the company to test RU-486 for its effects on fertility control.
Many tests were performed on rabbits, rats, and monkeys; they
showed that, even in the presence of progesterone, RU-486 could
prevent secretory tissue from forming in the uterus, could change
the timing of the menstrual cycle, and could terminate a pregnancy—that
is, cause an abortion. The compound also seemed to be
nontoxic, even in high doses.
In October of 1981, Baulieu began testing the drug with human
volunteers. By 1985, major tests of RU-486 were being done in
Étienne-Emile Baulieu
Étienne-Émile Baulieu was born in Strasbourg, France, in
1926. He moved to Paris for his advanced studies at the Faculty
of Medicine and Faculty of Science of Pasteur College. He was
an Intern of Paris from 1951 until he received a medical degree
in 1955. He passed examinations qualifying him to become a
teacher at state schools in 1958 and during the 1961-1962 academic
year was a visiting scientist in Columbia University’s
Department of Biochemistry.
In 1963 Baulieu was made a Doctor of Science and appointed
director of a research unit at France’s National Institute of
Health and Medical Science, a position he held until he retired
in 1997. He also served as Head of Service of Hormonal Biochemistry
of the Hospital of Bicêtre (1970-1997), professor of
biochemistry at University of Paris-South (1970-1993), and consultant
for Roussel Uclaf (1963-1997).
Among his many honors are the Gregory Pincus Memorial
Award (1978), awards from the National Academy of Medicine,
the Christopher Columbus Discovery Award in Biomedical Research
(1992), the Joseph Bolivar DeLee Humanitarian Award
(1994), and Commander of the Legion of Honor (1990). Although
busy with research and teaching duties, Baulieu was on
the editorial board of several French and international newspapers,
a member of scientific councils, and a participant in the
Special Program in Human Reproduction of the World Health
Organization.

France, Great Britain, The Netherlands, Sweden, and China. When a
relatively low dose of RU-486 was given orally, there was an 85 percent
success rate in ending pregnancy; the woman’s body expelled
the embryo and all the endometrial surface. Researchers found that
if a low dose of a prostaglandin (a hormonelike substance that
causes the smooth muscles of the uterus to contract, thereby expelling
the embryo) was given two days later, the success rate rose to 96
percent. There were few side effects, and the low doses of RU-486
did not interfere with the actions of other steroid hormones that are
necessary to keep the body working.
In the March, 1990, issue of The New England Journal of Medicine,
Baulieu and his coworkers reported that with one dose of RU-486,
followed in thirty-six to forty-eight hours with a low dose of prostaglandin,
96 percent of the 2,040 women they studied had a complete
abortion with few side effects. The women were monitored after receiving
the prostaglandin to watch for side effects, which included
nausea, vomiting, abdominal pain, and diarrhea. When they returned
for a later checkup, fewer than 2 percent of the women complained
of side effects. The researchers used two different prostaglandins;
they found that one caused a quicker abortion but also
brought about more pain and a longer period of bleeding.
Using the Drug
Abortion pill / 3
In September, 1988, the French government approved the distribution
of RU-486 for use in government-controlled clinics. The next
month, however, Roussel Uclaf stopped selling the drug because
people opposed to abortion did not want RU-486 to be available and
were threatening to boycott the company.
Then, however, there were threats and pressure from the other
side. For example, members of the World Congress of Obstetrics
and Gynecology announced that they might boycott Roussel Uclaf
if it did not make RU-486 available. The French government, which
controlled a 36 percent interest in Roussel Uclaf, ordered the company
to start distributing the drug once more.
By the fall of 1989, more than one-fourth of all early abortions in
France were being done with RU-486 and a prostaglandin. The French
government began helping to pay the cost of using RU-486 in 1990.

4 / Abortion pill
Testing for approval of RU-486 was completed in Great Britain
and The Netherlands, but Roussel Uclaf’s parent company, Hoechst
AG, did not try to market the drug there or in any other country outside
France. (In the United States, government regulations did not
allow RU-486 to be tested using government funds.)
Medical researchers believe that RU-486 may be useful not only
for abortions but also in other ways. For example, it may help in
treating certain breast cancers and other tumors. RU-486 is also being
investigated as a possible treatment for glaucoma—to lower
pressure in the eye that may be caused by a high level of steroid hormone.
It may be useful in promoting the healing of skin wounds
and softening the cervix at birth, easing delivery. Researchers hope
as well that some form of RU-486 may prove useful as a contraceptive—that
is, not to prevent a fertilized egg from implanting itself in
the mother’s uterus but to prevent ovulation in the first place.
Impact
Groups opposed to abortion rights have spoken out against RU-
486, while those who favor the right to abortion have urged its acceptance.
The drug has been approved for use in China as well as in
France. In the United States, however, the government has avoided
giving its approval to the drug. Officials of the World Health Organization
(WHO) have argued that RU-486 could prevent the deaths
of women who undergo botched abortions. Under international
law, WHO has the right to take control of the drug and make it available
in poor countries at low cost. Because of the controversy surrounding
the drug, however, WHO called for more testing to ensure
that RU-486 is quite safe for women.
See also Amniocentesis; Antibacterial drugs; Artificial hormone;
Birth control pill; Salvarsan.
Further Reading
Baulieu, Etienne-Emile, and Mort Rosenblum. The “Abortion Pill”:
RU-486, a Woman’s Choice. New York: Simon & Schuster, 1991.
Butler, John Douglas, and David F. Walbert. Abortion, Medicine, and
the Law. 4th ed. New York: Facts on File, 1992.

Abortion pill / 5
Lyall, Sarah. “Britain Allows Over-the-Counter Sales of Morning-
After Pill.” New York Times (January 15, 2001).
McCuen, Gary E. RU 486: The Abortion Pill Controversy. Hudson,
Wis.: GEM Publications, 1992.
Nemecek, Sasha. “The Second Abortion Pill.” Scientific American
283, no. 6 (December, 2000).
Zimmerman, Rachel. “Ads for Controversial Abortion Pill Set to
Appear in National Magazines.” Wall Street Journal (May 23,
2001).

6
Airplane
Airplane
The invention: The first heavier-than-air craft to fly, the airplane
revolutionized transportation and symbolized the technological
advances of the twentieth century.
The people behind the invention:
Wilbur Wright (1867-1912), an American inventor
Orville Wright (1871-1948), an American inventor
Octave Chanute (1832-1910), a French-born American civil
engineer
A Careful Search
Although people have dreamed about flying since the time of the
ancient Greeks, it was not until the late eighteenth century that hotair
balloons and gliders made human flight possible. It was not until
the late nineteenth century that enough experiments had been done
with kites and gliders that people could begin to think seriously
about powered, heavier-than-air flight. Two of these people were
Wilbur and Orville Wright.
The Wright brothers making their first successful powered flight, at Kitty Hawk, North
Carolina. (Library of Congress)

The Wright brothers were more than just tinkerers who accidentally
found out how to build a flying machine. In 1899, Wilbur wrote
the Smithsonian Institution for a list of books to help them learn
about flying. They used the research of people such as George
Cayley, Octave Chanute, Samuel Langley, and Otto Lilienthal to
help them plan their own experiments with birds, kites, and gliders.
They even built their own wind tunnel. They never fully trusted the
results of other people’s research, so they repeated the experiments
of others and drew their own conclusions. They shared these results
with Octave Chanute, who was able to offer them lots of good advice.
They were continuing a tradition of excellence in engineering
that began with careful research and avoided dangerous trial and
error.
Slow Success
Airplane / 7
Before the brothers had set their minds to flying, they had built
and repaired bicycles. This was a great help to them when they put
their research into practice and actually built an airplane. From
building bicycles, they knew how to work with wood and metal to
make a lightweight but sturdy machine. Just as important, from riding
bicycles, they got ideas about how an airplane needed to work.
They could see that both bicycles and airplanes needed to be fast
and light. They could also see that airplanes, like bicycles, needed to
be kept under constant control to stay balanced, and that this control
would probably take practice. This was a unique idea. Instead
of building something solid that was controlled by levers and wheels
like a car, the Wright brothers built a flexible airplane that was controlled
partly by the movement of the pilot, like a bicycle.
The result was the 1903 Wright Flyer. The Flyer had two sets of
wings, one above the other, which were about 12 meters from tip to
tip. They made their own 12-horsepower engine, as well as the two
propellers the engine spun. The craft had skids instead of wheels.
On December 14, 1903, the Wright brothers took the Wright Flyer to
the shores of Kitty Hawk, North Carolina, where Wilbur Wright
made the first attempt to fly the airplane.
The first thing Wilbur found was that flying an airplane was not
as easy as riding a bicycle. One wrong move sent him tumbling into

8 / Airplane
The Wright Brothers
Orville and his older brother Wilbur first got interested in
aircraft when their father gave them a toy helicopter in 1878.
Theirs was a large, supportive family. Their father, a minister,
and their mother, a college graduate and inventor of household
gadgets, encouraged all five of the children to be creative. Although
Wilbur, born in 1867, was four years older than Orville,
they were close as children. While in high school, they put out a
weekly newspaper together, West Side News, and they opened
their bicycle shop in 1892. Orville was the mechanically adept
member of the team, the tinkerer; Wilbur was the deliberative
one, the planner and designer.
Since the bicycle business was seasonal, they had time to
pursue their interest in aircraft, puzzling out the technical problems
and studying the successes and failures of others. They
started with gliders, flying their first, which had a five-foot
wing span, in 1899. They developed their own technique to control
the gliders, the “wing-warping technique,” after watching
how birds fly. They attached wires to the trailing edges of the
wings and pulled the wires to deform the wings’ shape. They
built a sixteen-foot glider in 1900 and spent a vacation in North
Carolina gaining flying experience. Further designs and many
more tests followed, including more than two hundred shapes
of wing studied in their home-built wind tunnel, before their
first successful engine-powered flight in 1903.
Neither man ever married. After Wilbur died of typhoid in
1912, Orville was stricken by the loss of his brother but continued
to run their business until 1915. He last piloted an airplane
himself in 1918 and died thirty years later.
Their first powered airplane, the Wright Flyer, lives on at the
National Air and Space Museum in Washington, D.C. Small
parts from the aircraft were taken to the Moon by Neil Armstrong
and Edwin Aldrin when they made the first landing
there in 1969.
the sand only moments after takeoff. Wilbur was not seriously hurt,
but a few more days were needed to repair the Wright Flyer.
On December 17, 1903, at 10:35 a.m., after eight years of research
and planning, Orville Wright took to the air for a historic twelve sec-

onds. He covered 37 meters of ground and 152 meters of air space.
Both brothers took two flights that morning. On the fourth flight,
Wilbur flew for fifty-nine seconds over 260 meters of ground and
through more than 800 meters of air space. After he had landed, a
sudden gust of wind struck the plane, damaging it beyond repair.
Yet no one was able to beat their record for three years.
Impact
Airplane / 9
Those first flights in 1903 got little publicity. Only a few people,
such as Octave Chanute, understood the significance of the Wright
brothers’ achievement. For the next two years, they continued to
work on their design, and by 1905 they had built the Wright Flyer III.
Although Chanute tried to get them to enter flying contests, the
brothers decided to be cautious and try to get their machine patented
first, so that no one would be able to steal their ideas.
News of their success spread slowly through the United States
and Europe, giving hope to others who were working on airplanes
of their own. When the Wright brothers finally went public with the
Wright Flyer III, they inspired many new advances. By 1910, when
the brothers started flying in air shows and contests, their feats were
matched by another American, Glen Hammond Curtiss. The age of
the airplane had arrived.
Later in the decade, the Wright brothers began to think of military
uses for their airplanes. They signed a contract with the U.S.
Army Signal Corps and agreed to train military pilots.
Aside from these achievements, the brothers from Dayton, Ohio,
set the standard for careful research and practical experimentation.
They taught the world not only how to fly but also how to design
airplanes. Indeed, their methods of purposeful, meaningful, and
highly organized research had an impact not only on airplane design
but also on the field of aviation science in general.
See also Bullet train; Cruise missile; Dirigible; Gas-electric car;
Propeller-coordinated machine gun; Rocket; Stealth aircraft; Supersonic
passenger plane; Turbojet; V-2 rocket.

10 / Airplane
Further Reading
Brady, Tim. The American Aviation Experience: A History. Carbondale:
Southern Illinois University Press, 2000.
Chanute, Octave, Marvin Wilks, Orville Wright, and Wilbur Wright.
The Papers of Wilbur and Orville Wright: Including the Chanute-
Wright Letters and Other Papers of Octave Chanute. New York:
McGraw-Hill, 2000.
Culik, Fred, and Spencer Dunmore. On Great White Wings: The
Wright Brothers and the Race for Flight. Toronto: McArthur, 2001.
Howard, Fred. Wilbur and Orville: A Biography of the Wright Brothers.
Mineola, N.Y.: Dover Publications, 1998.

Alkaline storage battery
Alkaline storage battery
The invention: The nickel-iron alkaline battery was a lightweight,
inexpensive portable power source for vehicles with electric motors.
The people behind the invention:
Thomas Alva Edison (1847-1931), American chemist, inventor,
and industrialist
Henry Ford (1863-1947), American inventor and industrialist
Charles F. Kettering (1876-1958), American engineer and
inventor
A Three-Way Race
The earliest automobiles were little more than pairs of bicycles
harnessed together within a rigid frame, and there was little agreement
at first regarding the best power source for such contraptions.
The steam engine, which was well established for railroad and ship
transportation, required an external combustion area and a boiler.
Internal combustion engines required hand cranking, which could
cause injury if the motor backfired. Electric motors were attractive
because they did not require the burning of fuel, but they required
batteries that could store a considerable amount of energy and
could be repeatedly recharged. Ninety percent of the motorcabs in
use in New York City in 1899 were electrically powered.
The first practical storage battery, which was invented by the
French physicist Gaston Planté in 1859, employed electrodes (conductors
that bring electricity into and out of a conducting medium)
of lead and lead oxide and a sulfuric acid electrolyte (a solution
that conducts electricity). In somewhat improved form, this
remained the only practical rechargeable battery at the beginning
of the twentieth century. Edison considered the lead acid cell (battery)
unsuitable as a power source for electric vehicles because using
lead, one of the densest metals known, resulted in a heavy
battery that added substantially to the power requirements of a
motorcar. In addition, the use of an acid electrolyte required that
11

12 / Alkaline storage battery
the battery container be either nonmetallic or coated with a nonmetal
and thus less dependable than a steel container.
The Edison Battery
In 1900, Edison began experiments aimed at developing a rechargeable
battery with inexpensive and lightweight metal electrodes and an
alkaline electrolyte so that a metal container could be used. He had already
been involved in manufacturing the nonrechargeable battery
known as the Lalande cell, which had zinc and copper oxide electrodes
and a highly alkaline sodium hydroxide electrolyte. Zinc electrodes
could not be used in a rechargeable cell because the zinc would
dissolve in the electrolyte. The copper electrode also turned out to be
unsatisfactory. After much further experimentation, Edison settled
on the nickel-iron system for his new storage battery. In this system,
the power-producing reaction involved the conversion of nickel oxide
to nickel hydroxide together with the oxidation of iron metal to
iron oxide, with both materials in contact with a potassium hydroxide
solution. When the battery was recharged, the nickel hydroxide
was converted into oxide and the iron oxide was converted back to
the pure metal.
Although the basic ingredients
of the Edison cell were
inexpensive, they could not readily
be obtained in adequate purity
for battery use. Edison set
up a new chemical works to
prepare the needed materials.
He purchased impure nickel alloy,
which was then dissolved
in acid, purified, and converted
to the hydroxide. He prepared
pure iron powder by using a
multiple-step process. For use
in the battery, the reactant powders
had to be packed in pockets
made of nickel-plated steel
Thomas A. Edison. (Library of Congress)
that had been perforated to al-

Alkaline storage battery / 13
low the iron and nickel powders to come into contact with the electrolyte.
Because the nickel compounds were poor electrical conductors,
a flaky type of graphite was mixed with the nickel hydroxide at
this stage.
Sales of the new Edison storage battery began in 1904, but within
six months it became apparent that the battery was subject to losses
in power and a variety of other defects. Edison took the battery off
Thomas Alva Edison
Thomas Alva Edison (1847-1931) was America’s most famous
and prolific inventor. His astonishing success story, rising
from a home-schooled child who worked as a newsboy to
a leader in American industry, was celebrated in children’s
books, biographies, and movies. Corporations still bear his
name, and his inventions and improvements of others’ inventions—such
as the light bulb, phonograph, and motion picture—shaped
the way Americans live, work, and entertain
themselves. The U.S. Patent Office issued Edison 1,093 patents
during his lifetime, the most granted to one person.
Hailed as a genius, Edison himself emphasized the value of
plain determination. Genius is one percent inspiration and 99
percent perspiration, he insisted. He also understood the value
of working with others. In fact, one of his greatest contributions
to American technology involved organized research. At age
twenty-three he sold the rights to his first major invention,
an improved ticker-tape machine for Wall Street brokers, for
$40,000. He invested the money in building an industrial research
laboratory, the first ever. It led to his large facilities at
Menlo Park, New Jersey, and, later, labs in other locations. At
times as many as one hundred people worked for him, some of
whom, such as Nikola Tesla and Reginald Fessenden, became
celebrated inventors in their own right.
At his labs Edison not only developed electrical items, such
as the light bulb and storage battery; he also produced an efficient
mimeograph and worked on innovations in metallurgy,
organic chemistry, photography and motion pictures, and phonography.
The phonograph, he once said, was his favorite invention.
Edison never stopped working. He was still receiving patents
the year he died.

14 / Alkaline storage battery
the market in 1905 and offered full-price refunds for the defective
batteries. Not a man to abandon an invention, however, he spent the
next five years examining the failed batteries and refining his design.
He discovered that the repeated charging and discharging of
the battery caused a shift in the distribution of the graphite in the
nickel hydroxide electrode. By using a different type of graphite, he
was able to eliminate this problem and produce a very dependable
power source.
The Ford Motor Company, founded by Henry Ford, a former
Edison employee, began the large-scale production of gasolinepowered
automobiles in 1903 and introduced the inexpensive, easyto-drive
Model T in 1908. The introduction of the improved Edison
battery in 1910 gave a boost to electric car manufacturers, but their
new position in the market would be short-lived. In 1911, Charles
Kettering invented an electric starter for gasoline-powered vehicles
that eliminated the need for troublesome and risky hand cranking.
By 1915, this device was available on all gasoline-powered automobiles,
and public interest in electrically powered cars rapidly diminished.
Although the Kettering starter required a battery, it required
much less capacity than an electric motor would have and was almost
ideally suited to the six-volt lead-acid battery.
Impact
Edison lost the race to produce an electrical power source that
would meet the needs of automotive transportation. Instead, the internal
combustion engine developed by Henry Ford became the standard.
Interest in electrically powered transportation diminished as
immense reserves of crude oil, from which gasoline could be obtained,
were discovered first in the southwestern United States and
then on the Arabian peninsula. Nevertheless, the Edison cell found
a variety of uses and has been manufactured continuously throughout
most of the twentieth century much as Edison designed it.
Electrically powered trucks proved to be well suited for local deliveries,
and some department stores maintained fleets of such
trucks into the mid-1920’s. Electrical power is still preferable to internal
combustion for indoor use, where exhaust fumes are a significant
problem, so forklifts in factories and passenger transport vehi-

cles at airports still make use of the Edison-type power source. The
Edison battery also continues to be used in mines, in railway signals,
in some communications equipment, and as a highly reliable
source of standby emergency power.
See also Compressed-air-accumulating power plant; Internal
combustion engine; Photoelectric cell; Photovoltaic cell.
Further Reading
Alkaline storage battery / 15
Baldwin, Neil. Edison: Inventing the Century. Chicago: University of
Chicago Press, 2001.
Boyd, Thomas Alvin. Professional Amateur: The Biography of Charles
Franklin Kettering. New York: Arno Press, 1972.
Bryan, Ford R. Beyond the Model T: The Other Ventures of Henry Ford.
Rev. ed. Detroit: Wayne State University Press, 1997.
Cramer, Carol. Thomas Edison. San Diego, Calif.: Greenhaven Press,
2001.
Israel, Paul. Edison: A Life of Invention. New York: Wiley, 2000.

16
Ammonia
Ammonia
The invention: The first successful method for converting nitrogen
from the atmosphere and combining it with hydrogen to synthesize
ammonia, a valuable compound used as a fertilizer.
The person behind the invention:
Fritz Haber (1868-1934), a German chemist who won the 1918
Nobel Prize in Chemistry
The Need for Nitrogen
The nitrogen content of the soil, essential to plant growth, is
maintained normally by the deposition and decay of old vegetation
and by nitrates in rainfall. If, however, the soil is used extensively
for agricultural purposes, more intensive methods must be used to
maintain soil nutrients such as nitrogen. One such method is crop
rotation, in which successive divisions of a farm are planted in rotation
with clover, corn, or wheat, for example, or allowed to lie fallow
for a year or so. The clover is able to absorb nitrogen from the air and
deposit it in the soil through its roots. As population has increased,
however, farming has become more intensive, and the use of artificial
fertilizers—some containing nitrogen—has become almost universal.
Nitrogen-bearing compounds, such as potassium nitrate and
ammonium chloride, have been used for many years as artificial fertilizers.
Much of the nitrate used, mainly potassium nitrate, came
from Chilean saltpeter, of which a yearly amount of half a million
tons was imported at the beginning of the twentieth century into
Europe and the United States for use in agriculture. Ammonia was
produced by dry distillation of bituminous coal and other lowgrade
fuel materials. Originally, coke ovens discharged this valuable
material into the atmosphere, but more economical methods
were found later to collect and condense these ammonia-bearing
vapors.
At the beginning of the twentieth century, Germany had practically
no source of fertilizer-grade nitrogen; almost all of its supply

came from the deserts of northern Chile. As demand for nitrates increased,
it became apparent that the supply from these vast deposits
would not be enough. Other sources needed to be found, and the almost
unlimited supply of nitrogen in the atmosphere (80 percent nitrogen)
was an obvious source.
Temperature and Pressure
Ammonia / 17
When Fritz Haber and coworkers began his experiments on ammonia
production in 1904, Haber decided to repeat the experiments
of the British chemist Sir William Ramsay and Sydney Young, who
in 1884 had studied the decomposition of ammonia at about 800 degrees
Celsius. They had found that a certain amount of ammonia
was always left undecomposed. In other words, the reaction between
ammonia and its constituent elements—nitrogen and hydrogen—had
reached a state of equilibrium.
Haber decided to determine the point at which this equilibrium
took place at temperatures near 1,000 degrees Celsius. He tried several
approaches, reacting pure hydrogen with pure nitrogen, and
starting with pure ammonia gas and using iron filings as a catalyst.
(Catalytic agents speed up a reaction without affecting it otherwise).
Having determined the point of equilibrium, he next tried different
catalysts and found nickel to be as effective as iron, and calcium
and manganese even better. At 1,000 degrees Celsius, the rate of reaction
was enough to produce practical amounts of ammonia continuously.
Further work by Haber showed that increasing the pressure also
increased the percentage of ammonia at equilibrium. For example,
at 300 degrees Celsius, the percentage of ammonia at equilibrium at
1 atmosphere of pressure was very small, but at 200 atmospheres,
the percentage of ammonia at equilibrium was far greater. A pilot
plant was constructed and was successful enough to impress a
chemical company, Badische Anilin-und Soda-Fabrik (BASF). BASF
agreed to study Haber’s process and to investigate different catalysts
on a large scale. Soon thereafter, the process became a commercial
success.

(Nobel Foundation)
18 / Ammonia
Impact
Fritz Haber
Fritz Haber’s career is a warning to inventors: Beware of
what you create, even if your intentions are honorable.
Considered a leading chemist of his age, Haber was born in
Breslau (now Wroclaw, Poland) in 1868. A brilliant student, he
earned a doctorate quickly, specializing in organic chemistry,
and briefly worked as an industrial chemist. Although he soon
took an academic job, throughout his career Haber believed
that science must benefit society—new theoretical discoveries
must find practical applications.
Beginning in 1904, he applied new chemical techniques
to fix atmospheric nitrogen in the form of ammonia.
Nitrogen in the form of nitrates was urgently
sought because nitrates were necessary to fertilize
crops and natural sources were becoming rare. Only
artificial nitrates could sustain the amount of agriculture
needed to feed expanding populations. In 1908
Haber succeeded in finding an efficient, cheap process
to make ammonia and convert it to nitrates, and
by 1910 German manufacturers had built large plants
to exploit his techniques. He was lauded as a great benefactor to
humanity.
However, his efforts to help Germany during World War I,
even though he hated war, turned his life into a nightmare. His
wife committed suicide because of his chlorine gas research,
which also poisoned his international reputation and tainted
his 1918 Nobel Prize in Chemistry. After the war he redirected
his energies to helping Germany rebuild its economy. Eight
years of experiments in extracting gold from seawater ended in
failure, but he did raise the Kaiser Wilhelm Institute for Physical
Chemistry, which he directed, to international prominence.
Nonetheless, Haber had to flee Adolf Hitler’s Nazi regime in
1933 and died a year later, better known for his war research
than for his fundamental service to agriculture and industry.
With the beginning of World War I, nitrates were needed more
urgently for use in explosives than in agriculture. After the fall of
Antwerp, 50,000 tons of Chilean saltpeter were discovered in the

harbor and fell into German hands. Because the ammonia from
Haber’s process could be converted readily into nitrates, it became
an important war resource. Haber’s other contribution to the German
war effort was his development of poison gas, which was used
for the chlorine gas attack on Allied troops at Ypres in 1915. He also
directed research on gas masks and other protective devices.
At the end of the war, the 1918 Nobel Prize in Chemistry was
awarded to Haber for his development of the process for making
synthetic ammonia. Because the war was still fresh in everyone’s
memory, it became one of the most controversial Nobel awards ever
made. A headline in The New York Times for January 26, 1920, stated:
“French Attack Swedes for Nobel Prize Award: Chemistry Honor
Given to Dr. Haber, Inventor of German Asphyxiating Gas.” In a letter
to the Times on January 28, 1920, the Swedish legation in Washington,
D.C., defended the award.
Haber left Germany in 1933 under duress from the anti-Semitic
policies of the Nazi authorities. He was invited to accept a position
with the University of Cambridge, England, and died on a trip to
Basel, Switzerland, a few months later, a great man whose spirit had
been crushed by the actions of an evil regime.
See also Fuel cell; Refrigerant gas; Silicones; Thermal cracking
process.
Further Reading
Ammonia / 19
Goran, Morris Herbert. The Story of Fritz Haber. Norman: University
of Oklahoma Press, 1967.
Jansen, Sarah. “Chemical-Warfare Techniques for Insect Control: Insect
‘Pests’ in Germany Before and After World War I.” Endeavour
24, no. 1 (March, 2000).
Smil, Vaclav. Enriching the Earth: Fritz Haber, Carl Bosch, and the Transformation
of World Food Production. Cambridge, Mass.: MIT Press,
2001.

20
Amniocentesis
Amniocentesis
The invention: A technique for removing amniotic fluid from
pregnant women, amniocentesis became a life-saving tool for diagnosing
fetal maturity, health, and genetic defects.
The people behind the invention:
Douglas Bevis, an English physician
Aubrey Milunsky (1936- ), an American pediatrician
How Babies Grow
For thousands of years, the inability to see or touch a fetus in the
uterus was a staggering problem in obstetric care and in the diagnosis
of the future mental and physical health of human offspring. A
beginning to the solution of this problem occurred on February 23,
1952, when The Lancet published a study called “The Antenatal Prediction
of a Hemolytic Disease of the Newborn.” This study, carried
out by physician Douglas Bevis, described the use of amniocentesis
to assess the risk factors found in the fetuses of Rh-negative women
impregnated by Rh-positive men. The article is viewed by many as a
landmark in medicine that led to the wide use of amniocentesis as a
tool for diagnosing fetal maturity, fetal health, and fetal genetic
deects.
At the beginning of a human pregnancy (conception) an egg and
a sperm unite to produce the fertilized egg that will become a new
human being. After conception, the fertilized egg passes from the
oviduct into the uterus, while dividing and becoming an organized
cluster of cells capable of carrying out different tasks in the ninemonth-long
series of events leading up to birth.
About a week after conception, the cluster of cells, now a “vesicle”
(a fluid-filled sac containing the new human cells), attaches
to the uterine lining, penetrates it, and becomes intimately intertwined
with uterine tissues. In time, the merger between the vesicle
and the uterus results in formation of a placenta that connects the
mother and the embryo, and an amniotic sac filled with the amniotic
fluid in which the embryo floats.

Amniotic Sac
Uterus
Amniotic Fluid
Placenta
Physicians extract amniotic fluid directly from the
womb and examine it to determine the health of the
fetus.
Eight weeks after conception,
the embryo (now a
fetus) is about 2.5 centimeters
long and possesses
all the anatomic elements
it will have when it is
born. At this time, about
two and one-half months
after her last menstruation,
the expectant mother typically
visits a physician and
finds out she is pregnant.
Also at this time, expecting
mothers often begin to
worry about possible birth
defects in the babies they
carry. Diabetic mothers and
mothers older than thirty-
five years have higher than usual chances of delivering babies who
have birth defects.
Many other factors inferred from the medical history an expecting
mother provides to her physician can indicate the possible appearance
of birth defects. In some cases, knowledge of possible
physical problems in a fetus may allow their treatment in the uterus
and save the newborn from problems that could persist throughout
life or lead to death in early childhood. Information is obtained
through the examination of the amniotic fluid in which the fetus is
suspended throughout pregnancy. The process of obtaining this
fluid is called “amniocentesis.”
Diagnosing Diseases Before Birth
Amniocentesis / 21
Amniocentesis is carried out in several steps. First, the placenta
and the fetus are located by the use of ultrasound techniques. Next,
the expecting mother may be given a local anesthetic; a long needle
is then inserted carefully into the amniotic sac. As soon as amniotic
fluid is seen, a small sample (about four teaspoons) is drawn into a
hypodermic syringe and the syringe is removed. Amniocentesis is

22 / Amniocentesis
nearly painless, and most patients feel only a little abdominal pressure
during the procedure.
The amniotic fluid of early pregnancy resembles blood serum.
As pregnancy continues, its content of substances from fetal urine
and other fetal secretions increases. The fluid also contains fetal cells
from skin and from the gastrointestinal, reproductive, and respiratory
tracts. Therefore, it is of great diagnostic use. Immediately after
the fluid is removed from the fetus, the fetal cells are separated out.
Then, the cells are used for genetic analysis and the amniotic fluid is
examined by means of various biochemical techniques.
One important use of the amniotic fluid from amniocentesis is
the determination of its lecithin and sphingomyelin content. Lecithins
and sphingomyelins are two types of body lipids (fatty molecules)
that are useful diagnostic tools. Lecithins are important because
they are essential components of the so-called pulmonary
surfactant of mature lungs. The pulmonary surfactant acts at lung
surfaces to prevent the collapse of the lung air sacs (alveoli) when a
person exhales.
Subnormal lecithin production in a fetus indicates that it most
likely will exhibit respiratory distress syndrome or a disease called
“hyaline membrane disease” after birth. Both diseases can be fatal,
so it is valuable to determine whether fetal lecithin levels are adequate
for appropriate lung function in the newborn baby. This is
particularly important in fetuses being carried by diabetic mothers,
who frequently produce newborns with such problems. Often, when
the risk of respiratory distress syndrome is identified through amniocentesis,
the fetus in question is injected with hormones that help it
produce mature lungs. This effect is then confirmed by the repeated
use of amniocentesis. Many other problems can also be identified by
the use of amniocentesis and corrected before the baby is born.
Consequences
In the years that have followed Bevis’s original observation, many
improvements in the methodology of amniocentesis and in the techniques
used in gathering and analyzing the genetic and biochemical
information obtained have led to good results. Hundreds of debilitating
hereditary diseases can be diagnosed and some ameliorated—by

the examination of amniotic fluid and fetal cells isolated by amniocentesis.
For many parents who have had a child afflicted by some hereditary
disease, the use of the technique has become a major consideration
in family planning. Furthermore, many physicians recommend strongly
that all mothers over the age of thirty-four be tested by amniocentesis
to assist in the diagnosis of Down syndrome, a congenital but nonhereditary
form of mental deficiency.
There remains the question of whether such solutions are morally
appropriate, but parents—and society—now have a choice resulting
from the techniques that have developed since Bevis’s 1952
observation. It is also hoped that these techniques will lead to
means for correcting and preventing diseases and preclude the need
for considering the therapeutic termination of any pregnancy.
See also Abortion pill; Birth control pill; CAT scanner; Electrocardiogram;
Electroencephalogram; Mammography; Nuclear magnetic
resonance; Pap test; Ultrasound; X-ray image intensifier.
Further Reading
Amniocentesis / 23
Milunsky, Aubrey. Genetic Disorders and the Fetus: Diagnosis, Prevention,
and Treatment. 3d ed. Baltimore: Johns Hopkins University
Press, 1992.
Rapp, Rayna. Testing Women, Testing the Fetus: The Social Impact of
Amniocentesis in America. New York: Routledge, 1999.
Rothenberg, Karen H., and Elizabeth Jean Thomson. Women and Prenatal
Testing: Facing the Challenges of Genetic Technology. Columbus:
Ohio State University Press, 1994.
Rothman, Barbara Katz. The Tentative Pregnancy: How Amniocentesis
Changes the Experience of Motherhood. New York: Norton, 1993.

24
Antibacterial drugs
Antibacterial drugs
The invention: Sulfonamides and other drugs that have proved effective
in combating many previously untreatable bacterial diseases.
The people behind the invention:
Gerhard Domagk (1895-1964), a German physician who was
awarded the 1939 Nobel Prize in Physiology or Medicine
Paul Ehrlich (1854-1915), a German chemist and bacteriologist
who was the cowinner of the 1908 Nobel Prize in Physiology
or Medicine
The Search for Magic Bullets
Although quinine had been used to treat malaria long before the
twentieth century, Paul Ehrlich, who discovered a large number of
useful drugs, is usually considered the father of modern chemotherapy.
Ehrlich was familiar with the technique of using dyes to stain
microorganisms in order to make them visible under a microscope,
and he suspected that some of these dyes might be used to poison
the microorganisms responsible for certain diseases without hurting
the patient. Ehrlich thus began to search for dyes that could act
as “magic bullets” that would destroy microorganisms and cure
diseases. From 1906 to 1910, Ehrlich tested numerous compounds
that had been developed by the German dye industry. He eventually
found that a number of complex trypan dyes would inhibit the
protozoans that caused African sleeping sickness.
Ehrlich and his coworkers also synthesized hundreds of organic
compounds that contained arsenic. In 1910, he found that one of
these compounds, salvarsan, was useful in curing syphilis, a sexually
transmitted disease caused by the bacterium Treponema. This
was an important discovery, because syphilis killed thousands of
people each year. Salvarsan, however, was often toxic to patients,
because it had to be taken in large doses for as long as two years to
effect a cure. Ehrlich thus searched for and found a less toxic arsenic
compound, neosalvarsan, which replaced salvarsan in 1912.

In 1915, tartar emetic (a compound containing the metal antimony)
was found to be useful in treating kala-azar, which was
caused by a protozoan. Kala-azar affected millions of people in Africa,
India, and Asia, causing much suffering and many deaths each
year. Two years later, it was discovered that injection of tartar emetic
into the blood of persons suffering from bilharziasis killed the
flatworms infecting the bladder, liver, and spleen. In 1920, suramin,
a colorless compound developed from trypan red, was introduced
to treat African sleeping sickness. It was much less toxic to the patient
than any of the drugs Ehrlich had developed, and a single dose
would give protection for more than a month. From the dye methylene
blue, chemists made mepacrine, a drug that was effective
against the protozoans that cause malaria. This chemical was introduced
in 1933 and used during World War II; its principal drawback
was that it could cause a patient’s skin to become yellow.
Well Worth the Effort
Antibacterial drugs / 25
Gerhard Domagk had been trained in medicine, but he turned to
research in an attempt to discover chemicals that would inhibit or
kill microorganisms. In 1927, he became director of experimental
pathology and bacteriology at the Elberfeld laboratories of the German
chemical firm I. G. Farbenindustrie. Ehrlich’s discovery that
trypan dyes selectively poisoned microorganisms suggested to Domagk
that he look for antimicrobials in a new group of chemicals
known as azo dyes. A number of these dyes were synthesized
from sulfonamides and purified by Fritz Mietzsch and Josef Klarer.
Domagk found that many of these dyes protected mice infected
with the bacteria Streptococcus pyogenes. In 1932, he discovered that
one of these dyes was much more effective than any tested previously.
This red azo dye containing a sulfonamide was named prontosil
rubrum.
From 1932 to 1935, Domagk began a rigorous testing program to
determine the effectiveness and dangers of prontosil use at different
doses in animals. Since all chemicals injected into animals or humans
are potentially dangerous, Domagk determined the doses that
harmed or killed. In addition, he worked out the lowest doses that
would eliminate the pathogen. The firm supplied samples of the

26 / Antibacterial drugs
drug to physicians to carry out clinical trials on humans. (Animal
experimentation can give only an indication of which chemicals
might be useful in humans and which doses are required.)
Domagk thus learned which doses were effective and safe. This
knowledge saved his daughter’s life. One day while knitting, Domagk’s
daughter punctured her finger with a needle and was infected
with a virulent bacteria, which quickly multiplied and spread
from the wound into neighboring tissues. In an attempt to alleviate
the swelling, the infected area was lanced and allowed to drain, but
this did not stop the infection from spreading. The child became
critically ill with developing septicemia, or blood poisoning.
In those days, more than 75 percent of those who acquired blood
infections died. Domagk realized that the chances for his daughter’s
survival were poor. In desperation, he obtained some of the powdered
prontosil that had worked so well on infected animals. He extrapolated
from his animal experiments how much to give his
daughter so that the bacteria would be killed but his daughter
would not be poisoned. Within hours of the first treatment, her fever
dropped, and she recovered completely after repeated doses of
prontosil.
Impact
Directly and indirectly, Ehrlich’s and Domagk’s work served to
usher in a new medical age. Prior to the discovery that prontosil
could be use to treat bacterial infection and the subsequent development
of a series of sulfonamides, or “sulfa drugs,” there was no
chemical defense against this type of disease; as a result, illnesses
such as streptococcal infection, gonorrhea, and pneumonia held terrors
of which they have largely been shorn. Asmall injury could easily
lead to death.
By following the clues presented by the synthetic sulfa drugs and
how they worked to destroy bacteria, other scientists were able to
develop an even more powerful type of drug, the antibiotic. When
the American bacteriologist Rene Dubos discovered that natural organisms
could also be used to fight bacteria, interest was renewed in
an earlier discovery by the Scottish bacteriologist Sir Alexander: the
development of penicillin.

Antibiotics such as penicillin and streptomycin have become
some of the most important tools in fighting disease. Antibiotics
have replaced sulfa drugs for most uses, in part because they cause
fewer side effects, but sulfa drugs are still used for a handful of purposes.
Together, sulfonamides and antibiotics have offered the possibility
of a cure to millions of people who previously would have
had little chance of survival.
See also Penicillin; Polio vaccine (Sabin); Polio vaccine (Salk);
Salvarsan; Tuberculosis vaccine; Typhus vaccine; Yellow fever vaccine.
Further Reading
Antibacterial drugs / 27
Alstaedter, Rosemarie. From Germanin to Acylureidopenicillin: Research
That Made History: Documentation of a Scientific Revolution:
Dedicated to Gerhardt Domagk on the Eighty-fifth Anniversary of His
Birth. Leverkausen, West Germany: Bayer AG, 1980.
Baumler, Ernst. Paul Ehrlich: Scientist for Life. New York: Holmes and
Meier, 1984.
Galdston, Iago. Behind the Sulfa Drugs, a Short History of Chemotherapy.
New York: D. Appleton-Century, 1943.
Physiology or Medicine, 1922-1941. River Edge, N.J.: World Scientific,
1999.

28
Apple II computer
Apple II computer
The invention: The first commercially available, preassembled
personal computer, the Apple II helped move computers out of
the workplace and into the home.
The people behind the invention:
Stephen Wozniak (1950- ), cofounder of Apple and designer
of the Apple II computer
Steven Jobs (1955- ), cofounder of Apple
Regis McKenna (1939- ), owner of the Silicon Valley public
relations and advertising company that handled the Apple
account
Chris Espinosa (1961- ), the high school student who wrote
the BASIC program shipped with the Apple II
Randy Wigginton (1960- ), a high school student and Apple
software programmer
Inventing the Apple
As late as the 1960’s, not many people in the computer industry
believed that a small computer could be useful to the average person.
It was through the effort of two friends from the Silicon Valley—the
high-technology area between San Francisco and San Jose—
that the personal computer revolution was started.
Both Steven Jobs and Stephen Wozniak had attended Homestead
High School in Los Altos, California, and both developed early interests
in technology, especially computers. In 1971, Wozniak built
his first computer from spare parts. Shortly after this, he was introduced
to Jobs. Jobs had already developed an interest in electronics
(he once telephoned William Hewlett, cofounder of Hewlett-
Packard, to ask for parts), and he and Wozniak became friends.
Their first business together was the construction and sale of “blue
boxes,” illegal devices that allowed the user to make long-distance
telephone calls for free.
After attending college, the two took jobs within the electronics
industry. Wozniak began working at Hewlett-Packard, where he

studied calculator design, and Jobs took a job at Atari, the video
company. The friendship paid off again when Wozniak, at Jobs’s request,
designed the game “Breakout” for Atari, and the pair was
paid seven hundred dollars.
In 1975, the Altair computer, a personal computer in kit form,
was introduced by Micro Instrumentation and Telemetry Systems
(MITS). Shortly thereafter, the first personal computer club, the
Homebrew Computer Club, began meeting in Menlo Park, near
Stanford University. Wozniak and Jobs began attending the meeting
regularly. Wozniak eagerly examined the Altairs that others
brought. He thought that the design could be improved. In only a
few more weeks, he produced a circuit board and interfaces that
connected it to a keyboard and a video monitor. He showed the machine
at a Homebrew meeting and distributed photocopies of the
design.
In this new machine, which he named an “Apple,” Jobs saw a big
opportunity. He talked Wozniak into forming a partnership to develop
personal computers. Jobs sold his car, and Wozniak sold his
two Hewlett-Packard calculators; with the money, they ordered
printed circuit boards made. Their break came when Paul Terrell, a
retailer, was so impressed that he ordered fifty fully assembled Apples.
Within thirty days, the computers were completed, and they
sold for a fairly high price: $666.66.
During the summer of 1976, Wozniak kept improving the Apple.
The new computer would come with a keyboard, an internal power
supply, a built-in computer language called the Beginner’s All-
Purpose Symbolic Instruction Code” (BASIC), hookups for adding
printers and other devices, and color graphics, all enclosed in a plastic
case. The output would be seen on a television screen. The machine
would sell for twelve hundred dollars.
Selling the Apple
Apple II computer / 29
Regis McKenna was the head of the Regis McKenna Public Relations
agency, the best of the public relations firms that served the
high-technology industries of the valley, which Jobs wanted to handle
the Apple account. At first, McKenna rejected the offer, but
Jobs’s constant pleading finally convinced him. The agency’s first

30 / Apple II computer
Steven Jobs
While IBM and other corporations were devoting massive
resources and talent to designing a small computer in 1975,
Steven Paul Jobs and Stephen Wozniak, members of the tiny
Homebrew Computer Club, put together the first truly userfriendly
personal computer in Wozniak’s home. Jobs admitted
later that “Woz” was the engineering brains. Jobs himself was
the brains of design and marketing. Both had to scrape together
money for the project from their small salaries as low-level electronics
workers. Within eight years, Jobs headed the most progressive
company in the new personal computer industry and
was worth an estimated $210 million.
Little in his background foretold such fast, large material
success. Jobs was born in 1955 and became an orphan. Adopted
by Paul and Clara Jobs, he grew up in California towns near the
area that became known as Silicon Valley. He did not like school
much and was considered a loner, albeit one who always had a
distinctive way of thinking about things. Still in high school, he
impressed William Hewlett, founder of Hewlett-Packard in
Palo Alto, and won a summer job at the company, as well as
some free equipment for one of his school projects.
However, he dropped out of Reed College after one semester
and became a hippie. He studied philosophy and Chinese
and Indian mysticism. He became a vegetarian and practiced
meditation. He even shaved his head and traveled to India on a
spiritual pilgrimage. When he returned to America, however,
he also returned to his interest in electronics and computers.
Through various jobs at his original company, Apple, and elsewhere,
he stayed there.
contributions to Apple were the colorful striped Apple logo and a
color ad in Playboy magazine.
In February, 1977, the first Apple Computer office was opened in
Cupertino, California. By this time, two of Wozniak’s friends from
Homebrew, Randy Wigginton and Chris Espinosa—both high school
students—had joined the company. Their specialty was writing software.
Espinosa worked through his Christmas vacation so that BA-
SIC (the built-in computer language) could ship with the computer.

The team pushed ahead to complete the new Apple in time to
display it at the First West Coast Computer Faire in April, 1977. At
this time, the name “Apple II” was chosen for the new model. The
Apple II computer debuted at the convention and included many
innovations. The “motherboard” was far simpler and more elegantly
designed than that of any previous computer, and the ease of
connecting the Apple II to a television screen made it that much
more attractive to consumers.
Consequences
Apple II computer / 31
The introduction of the Apple II computer launched what was to
be a wave of new computers aimed at the home and small-business
markets. Within a few months of the Apple II’s introduction, Commodore
introduced its PET computer and Tandy Corporation/Radio
Shack brought out its TRS-80. Apple continued to increase the
types of things that its computers could do and worked out a distribution
deal with the new ComputerLand chain of stores.
In December, 1977, Wozniak began work on creating a floppy
disk system for the Apple II. (Afloppy disk is a small, flexible plastic
disk coated with magnetic material. The magnetized surface enables
computer data to be stored on the disk.) The cassette tape storage
on which all personal computers then depended was slow and
unreliable. Floppy disks, which had been introduced for larger computers
by the International Business Machines (IBM) Corporation in
1970, were fast and reliable. As he did with everything that interested
him, Wozniak spent almost all of his time learning about and
designing a floppy disk drive. When the final drive shipped in June,
1978, it made possible development of more powerful software for
the computer.
By 1980, Apple had sold 130,000 Apple II’s. That year, the company
went public, and Jobs and Wozniak, among others, became
wealthy. Three years later, Apple became the youngest company to
make the Fortune 500 list of the largest industrial companies. By
then, IBM had entered the personal computer field and had begun
to dominate it, but the Apple II’s earlier success ensured that personal
computers would not be a market fad. By the end of the
1980’s, 35 million personal computers would be in use.

32 / Apple II computer
See also BINAC computer; Colossus computer; ENIAC computer;
Floppy disk; Hard disk; IBM Model 1401 computer; Personal
computer; UNIVAC computer.
Further Reading
Carlton, Jim. Apple: The Inside Story of Intrigue, Egomania, and Business
Blunders. Rev. ed. London: Random House, 1999.
Gold, Rebecca. Steve Wozniak: A Wizard Called Woz. Minneapolis:
Lerner, 1994.
Linzmayer, Owen W. Apple Confidential: The Real Story of Apple Computer,
Inc. San Francisco: No Starch Press, 1999.
Moritz, Michael. The Little Kingdom: The Private Story of Apple Computer.
New York: Morrow, 1984.
Rose, Frank. West of Eden: The End of Innocence at Apple Computer.
New York: Viking, 1989.

Aqualung
Aqualung
The invention: A device that allows divers to descend hundreds of
meters below the surface of the ocean by enabling them to carry
the oxygen they breathe with them.
The people behind the invention:
Jacques-Yves Cousteau (1910-1997), a French navy officer,
undersea explorer, inventor, and author
Émile Gagnan, a French engineer who invented an automatic
air-regulating device
The Limitations of Early Diving
Undersea dives have been made since ancient times for the purposes
of spying, recovering lost treasures from wrecks, and obtaining
natural treasures (such as pearls). Many attempts have been made
since then to prolong the amount of time divers could remain underwater.
The first device, described by the Greek philosopher Aristotle
in 335 b.c.e., was probably the ancestor of the modern snorkel. It was
a bent reed placed in the mouth, with one end above the water.
In addition to depth limitations set by the length of the reed,
pressure considerations also presented a problem. The pressure on
a diver’s body increases by about one-half pound per square centimeter
for every meter ventured below the surface. After descending
about 0.9 meter, inhaling surface air through a snorkel becomes difficult
because the human chest muscles are no longer strong enough
to inflate the chest. In order to breathe at or below this depth, a diver
must breathe air that has been pressurized; moreover, that pressure
must be able to vary as the diver descends or ascends.
Few changes were possible in the technology of diving until air
compressors were invented during the early nineteenth century.
Fresh, pressurized air could then be supplied to divers. At first, the
divers who used this method had to wear diving suits, complete
with fishbowl-like helmets. This “tethered” diving made divers relatively
immobile but allowed them to search for sunken treasure or
do other complex jobs at great depths.
33

34 / Aqualung
The Development of Scuba Diving
The invention of scuba gear gave divers more freedom to
move about and made them less dependent on heavy equipment.
(“Scuba” stands for self-contained underwater breathing apparatus.)
Its development occurred in several stages. In 1880, Henry
Fleuss of England developed an outfit that used a belt containing
pure oxygen. Belt and diver were connected, and the diver breathed
the oxygen over and over. A version of this system was used by the
U.S. Navy in World War II spying efforts. Nevertheless, it had serious
drawbacks: Pure oxygen was toxic to divers at depths greater
than 9 meters, and divers could carry only enough oxygen for relatively
short dives. It did have an advantage for spies, namely, that
the oxygen—breathed over and over in a closed system—did not
reach the surface in the form of telltale bubbles.
The next stage of scuba development occurred with the design
of metal tanks that were able to hold highly compressed air.
This enabled divers to use air rather than the potentially toxic
pure oxygen. More important, being hooked up to a greater supply
of air meant that divers could stay under water longer. Initially,
the main problem with the system was that the air flowed continuously
through a mask that covered the diver’s entire face. This process
wasted air, and the scuba divers expelled a continual stream
of air bubbles that made spying difficult. The solution, according to
Axel Madsen’s Cousteau (1986), was “a valve that would allow inhaling
and exhaling through the same mouthpiece.”
Jacques-Yves Cousteau’s father was an executive for Air Liquide—
France’s main producer of industrial gases. He was able to direct
Cousteau to Émile Gagnan, an engineer at thecompany’s Paris laboratory
who had been developing an automatic gas shutoff valve for Air
Liquide. This valve became the Cousteau-Gagnan regulator, a breathing
device that fed air to the diver at just the right pressure whenever
he or she inhaled.
With this valve—and funding from Air Liquide—Cousteau and
Gagnan set out to design what would become the Aqualung. The
first Aqualungs could be used at depths of up to 68.5 meters. During
testing, however, the dangers of Aqualung diving became apparent.
For example, unless divers ascended and descended in slow stages,

Jacques-Yves Cousteau
Aqualung / 35
The son of a businessman who liked to travel, Jacques-Yves
Cousteau acquired the same wanderlust. Born in 1910 in Saint-
André-de-Cubzac, France, he was a sickly child, but he learned
to love swimming and the ocean. He also took an interest in
movies, producing his first film when he was thirteen.
Cousteau graduated from France’s naval academy, but his
career as an officer ended with a nearly fatal car accident in
1936. He went to Toulon, where he returned to his interests in
the sea and photography, a period that culminated in his invention
of the aqualung with Émile Gagnan in 1944. During
World War II he also won a Légion d’honneur for
his photographic espionage. The French Navy established
the Underwater Research Group for Cousteau
in 1944, and after the war the venture evolved into the
freewheeling, worldwide voyages that Cousteau became
famous for. Aboard the Calypso, a converted
U.S. minesweeper, he and his crew conducted research
and pioneered underwater photography. His
1957 documentary The Silent World (based on a 1953
book) won an Oscar and the Palm d’Or of the Cannes film
festival. Subsequent movies and The Undersea World of Jacques
Cousteau, a television series, established Cousteau as a leading
environmentalist and science educator. His Cousteau Society,
dedicated to exploring and protecting the oceans, attracted
millions of members worldwide. Through it he launched another
innovative technology, “Turbosails,” towering non-rotating
cylinders that act as sails to reduce ships’ dependency on oilfueled
engines. A new ship propelled by them, the Alcyone, eventually
replaced the Calypso.
Cousteau inspired legions of oceanographers and environmentalists
while calling attention to pressing problems in the
world’s oceans. Although his later years where marked by family
tragedies and controversy, he was revered throughout the
world and had received many honors when he died in 1997.
it was likely that they would get “the bends” (decompression sickness),
the feared disease of earlier, tethered deep-sea divers. Another
problem was that, below 42.6 meters, divers encountered nitrogen
narcosis. (This can lead to impaired judgment that may cause
(Library of Congress)

36 / Aqualung
fatal actions, including removing a mouthpiece or developing an
overpowering desire to continue diving downward, to dangerous
depths.)
Cousteau believed that the Aqualung had tremendous military
potential. During World War II, he traveled to London soon after the
Normandy invasion, hoping to persuade the Allied Powers of its
usefulness. He was not successful. So Cousteau returned to Paris
and convinced France’s new government to use Aqualungs to locate
and neutralize underwater mines laid along the French coast by
the German navy. Cousteau was commissioned to combine minesweeping
with the study of the physiology of scuba diving. Further
research revealed that the use of helium-oxygen mixtures increased
to 76 meters the depth to which a scuba diver could go without suffering
nitrogen narcosis.
Impact
One way to describe the effects of the development of the Aqualung
is to summarize Cousteau’s continued efforts to the present. In
1946, he and Philippe Tailliez established the Undersea Research
Group of Toulon to study diving techniques and various aspects of
life in the oceans. They studied marine life in the Red Sea from 1951
to 1952. From 1952 to 1956, they engaged in an expedition supported
by the National Geographic Society. By that time, the Research
Group had developed many techniques that enabled them to
identify life-forms and conditions at great depths.
Throughout their undersea studies, Cousteau and his coworkers
continued to develop better techniques for scuba diving, for recording
observations by means of still and television photography, and
for collecting plant and animal specimens. In addition, Cousteau
participated (with Swiss physicist Auguste Piccard) in the construction
of the deep-submergence research vehicle, or bathyscaphe. In
the 1960’s, he directed a program called Conshelf, which tested a
human’s ability to live in a specially built underwater habitat. He
also wrote and produced films on underwater exploration that attracted,
entertained, and educated millions of people.
Cousteau has won numerous medals and scientific distinctions.
These include the Gold Medal of the National Geographic Society

(1963), the United Nations International Environment Prize (1977),
membership in the American and Indian academies of science (1968
and 1978, respectively), and honorary doctor of science degrees
from the University of California, Berkeley (1970), Harvard University
(1979), and Rensselaer Polytechnical Institute (1979).
See also Bathyscaphe; Bathysphere.
Further Reading
Aqualung / 37
Cousteau, Jacques Yves. The Silent World. New York: Harper &
Brothers, 1952.
_____. “Lord of The Depths. Time 153, no. 12 (March 29, 1999).
_____, and James Dugan. The Living Sea. London: Elm Tree, 1988.
Madsen, Axel. Cousteau: An Unauthorized Biography. New York:
Beaufort Books, 1986.
Munson, Richard. Cousteau: The Captain and His World. New York:
Paragon House, 1991.
Zanelli, Leo, and George T. Skuse. Sub-Aqua Illustrated Dictionary.
New York: Oxford University Press, 1976.

38
Artificial blood
Artificial blood
The invention: A perfluorocarbon emulsion that serves as a blood
plasma substitute in the treatment of human patients.
The person behind the invention:
Ryoichi Naito (1906-1982), a Japanese physician
Blood Substitutes
The use of blood and blood products in humans is a very complicated
issue. Substances present in blood serve no specific purpose
and can be dangerous or deadly, especially when blood or blood
products are taken from one person and given to another. This fact,
combined with the necessity for long-term blood storage, a shortage
of donors, and some patients’ refusal to use blood for religious reasons,
brought about an intense search for a universal bloodlike substance.
The life-sustaining properties of blood (for example, oxygen transport)
can be entirely replaced by a synthetic mixture of known chemicals.
Fluorocarbons are compounds that consist of molecules containing
only fluorine and carbon atoms. These compounds are interesting
to physiologists because they are chemically and pharmacologically
inert and because they dissolve oxygen and other gases.
Studies of fluorocarbons as blood substitutes began in 1966,
when it was shown that a mouse breathing a fluorocarbon liquid
treated with oxygen could survive. Subsequent research involved
the use of fluorocarbons to play the role of red blood cells in transporting
oxygen. Encouraging results led to the total replacement of
blood in a rat, and the success of this experiment led in turn to trials
in other mammals, culminating in 1979 with the use of fluorocarbons
in humans.
Clinical Studies
The chemical selected for the clinical studies was Fluosol-DA,
produced by the Japanese Green Cross Corporation. Fluosol-DA

consists of a 20 percent emulsion of two perfluorocarbons (perfluorodecalin
and perfluorotripopylamine), emulsifiers, and salts
that are included to give the chemical some of the properties of
blood plasma. Fluosol-DA had been tested in monkeys, and it had
shown a rapid reversible uptake and release of oxygen, a reasonably
rapid excretion, no carcinogenicity or irreversible changes in the animals’
systems, and the recovery of blood components to normal
ranges within three weeks of administration.
The clinical studies were divided into three phases. The first
phase consisted of the administration of Fluosol-DA to normal human
volunteers. Twelve healthy volunteers were administered the
chemical, and the emulsion’s effects on blood pressure and composition
and on heart, liver, and kidney functions were monitored. No
adverse effects were found in any case. The first phase ended in
March, 1979, and based on its positive results, the second and third
phases were begun in April, 1979.
Twenty-four Japanese medical institutions were involved in the
next two phases. The reasons for the use of Fluosol-DA instead of
blood in the patients involved were various, and they included refusal
of transfusion for religious reasons, lack of compatible blood,
“bloodless” surgery for protection from risk of hepatitis, and treatment
of carbon monoxide intoxication.
Among the effects noticed by the patients were the following: a
small increase in blood pressure, with no corresponding effects on
respiration and body temperature; an increase in blood oxygen content;
bodily elimination of half the chemical within six to nineteen
hours, depending on the initial dose administered; no change in
red-cell count or hemoglobin content of blood; no change in wholeblood
coagulation time; and no significant blood-chemistry changes.
These results made the clinical trials a success and opened the door
for other, more extensive ones.
Impact
Artificial blood / 39
Perfluorocarbon emulsions were initially proposed as oxygencarrying
resuscitation fluids, or blood substitutes, and the results of
the pioneering studies show their success as such. Their success in
this area, however, led to advanced studies and expanded use of

40 / Artificial blood
these compounds in many areas of clinical medicine and biomedical
research.
Perfluorocarbon emulsions are useful in cancer therapy, because
they increase the oxygenation of tumor cells and therefore sensitize
them to the effects of radiation or chemotherapy. Perfluorocarbons
can also be used as “contrasting agents” to facilitate magnetic resonance
imaging studies of various tissues; for example, the uptake of
particles of the emulsion by the cells of malignant tissues makes it
possible to locate tumors. Perfluorocarbons also have a high nitrogen
solubility and therefore can be used to alleviate the potentially
fatal effects of decompression sickness by “mopping up” nitrogen
gas bubbles from the circulation system. They can also be used to
preserve isolated organs and amputated extremities until they can
be reimplanted or reattached. In addition, the emulsions are used in
cell cultures to regulate gas supply and to improve cell growth and
productivity.
The biomedical applications of perfluorocarbon emulsions are
multidisciplinary, involving areas as diverse as tissue imaging, organ
preservation, cancer therapy, and cell culture. The successful
clinical trials opened the door for new applications of these
compounds, which rank among the most versatile compounds exploited
by humankind.
See also Artificial heart; Artificial hormone; Artificial kidney;
Blood transfusion; Coronary artery bypass surgery; Electrocardiogram;
Heart-lung machine.
Further Reading
“Artificial Blood Product May Debut in Two Years.” Health Care
Strategic Management 18, no. 8 (August, 2000).
“The Business of Blood: Ryoichi Naito and Fluosol-DA Artificial
Blood.” Forbes 131 (January 17, 1983).
Glanz, James. “Pulse Quickens in Search for Blood Substitute.” Research
& Development 34, no. 10 (September, 1992).
Tsuchida, E. Artificial Red Cells: Materials, Performances, and Clinical
Study as Blood Substitutes. New York: Wiley, 1997.

Artificial chromosome
Artificial chromosome
The invention: Originally developed for use in the study of natural
chromosome behavior, the artificial chromosome proved to be a
valuable tool for recombinant DNA technology.
The people behind the invention:
Jack W. Szostak (1952- ), a British-born Canadian professor
at Harvard Medical School
Andrew W. Murray (1956- ), a graduate student
The Value of Artificial Chromosomes
The artificial chromosome gives biologists insight into the fundamental
mechanisms by which cells replicate and plays an important
role as a tool in genetic engineering technology. Soon after its invention
in 1983 by Andrew W. Murray and Jack W. Szostak, the artificial
chromosome was judged by scientists to be important and its value
in the field of medicine was exploited.
Chromosomes are essentially carriers of genetic information;
that is, they possess the genetic code that is the blueprint for life. In
higher organisms, the number and type of chromosomes that a cell
contains in its nucleus are characteristic of the species. For example,
each human cell has forty-six chromosomes, while the garden pea
has fourteen and the guinea pig has sixty-four. The chromosome’s
job in a dividing cell is to replicate and then distribute one copy of itself
into each new “daughter” cell. This process, which is referred to
as “mitosis” or “meiosis,” depending upon the actual mechanism
by which the process occurs, is of supreme importance to the continuation
of life.
In 1953, when biophysicists James D. Watson and Francis Crick
discovered the structure of deoxyribonucleic acid (DNA), an achievement
for which they won the 1962 Nobel Prize in Physiology or
Medicine, it was immediately apparent to them how the doublehelical
form of DNA (which looks something like a twisted ladder)
might explain the mechanism behind cell division. During DNA
replication, the chromosome unwinds to expose the thin threads of
41

42 / Artificial chromosome
DNA. The two strands of the double helix separate, and each acts as
a template for the formation of a new complementary strand, thus
forming two complete and identical chromosomes that can be distributed
to each new cell. This distribution process, which is referred
to as “segregation,” relies on the chromosomes being pulled along a
microtubule framework in the cell called the “mitotic spindle.”
Creating Artificial Chromosomes
An artificial chromosome is a laboratory-designed chromosome
that possesses only those functional elements its creators choose. In
order to be a true working chromosome, however, it must, at minimum,
maintain the machinery necessary for replication and segregation.
By the early 1980’s, Murray and Szostak had recognized the possible
advantages of using a simple, controlled model to study chromosome
behavior, since there are several difficulties associated
with studying chromosomes in their natural state. Since natural
chromosomes are large and have poorly defined structures, it is almost
impossible to sift out for study those elements that are essential
for replication and segregation. Previous methods of altering a
natural chromosome and observing the effects were difficult to use
because the cells containing that altered chromosome usually died.
Furthermore, even if the cell survived, analysis was complicated by
the extensive amount of genetic information carried by the chromosome.
Artificial chromosomes are simple and have known components,
although the functions of those components may be poorly
understood. In addition, since artificial chromosomes are extra chromosomes
that are carried by the cell, their alteration does not kill the
cell.
Prior to the synthesis of the first artificial chromosome, the essential
functional chromosomal elements of replication and segregation
had to be identified and harvested. One of the three chromosomal
elements thought to be required is the origin of replication,
the site at which the synthesis of new DNA begins. The relatively
weak interaction between DNA strands at this site facilitates their
separation, making possible—with the help of appropriate enzymes—
the subsequent replication of the strands into “sister chromatids.”

The second essential element is the “centromere,” a thinner segment
of the chromosome that serves as the attachment site for the mitotic
spindle. Sister chromatids are pulled into diametric ends of the dividing
cell by the spindle apparatus, thus forming two identical
daughter cells. The final functional elements are repetitive sequences
of DNA called “telomeres,” which are located at both ends of the
chromosome. The telomeres are needed to protect the terminal
genes from degradation.
With all the functional elements at their disposal, Murray and
Szostak proceeded to construct their first artificial chromosome.
Once made, this chromosome would be inserted into yeast cells to
replicate, since yeast cells are relatively simple and well characterized
but otherwise resemble cells of higher organisms. Construction
begins with a commonly used “bacterial plasmid,” a small, circular,
autonomously replicating section of DNA. Enzymes are then called
upon to create a gap in this “cloning vector” into which the three
chromosomal elements are spliced. In addition, genes that confer
some distinct trait, such as color, to yeast cells are also inserted, thus
making it possible to determine which cells have actually taken up
the new chromosome. Although their first attempt resulted in a
chromosome that failed to segregate properly, by September, 1983,
Murray and Szostak had announced in the prestigious British journal
Nature their success in creating the first artificial chromosome.
Consequences
Artificial chromosome / 43
One of the most exciting aspects of the artificial chromosome is
its application to recombinant DNA technology, which involves creating
novel genetic materials by combining segments of DNA from
various sources. For example, the artificial yeast chromosome can
be used as a cloning vector. In this process, a segment of DNA containing
some desired gene is inserted into an artificial chromosome
and is then allowed to replicate in yeast until large amounts of the
gene are produced. David T. Burke, Georges F. Carle, and Maynard
Victor Olson at Washington University in St. Louis have pioneered
the technique of combining human genes with artificial yeast chromosomes
and have succeeded in cloning large segments of human
DNA.

44 / Artificial chromosome
Although amplifying DNA in this manner has been done before,
using bacterial plasmids as cloning vectors, the artificial yeast chromosome
has the advantage of being able to hold much larger segments
of DNA, thus allowing scientists to clone very large genes.
This is of great importance, since the genes that cause diseases such
as hemophilia and Duchenne’s muscular dystrophy are enormous.
The most ambitious project for which the artificial yeast chromosome
is being used is the national project whose intent is to clone the
entire human genome.
See also Artificial blood; Artificial hormone; Genetic “fingerprinting”;
Genetically engineered insulin; In vitro plant culture;
Synthetic DNA; Synthetic RNA.
Further Reading
“Evolving RNA with Enzyme-Like Action.” Science News 144 (August
14, 1993).
Freedman, David H. “Playing God: The Handmade Cell.” Discover
13, no. 8 (August, 1992).
Varshavsky, Alexander. “The 2000 Genetics Society of America
Medal: Jack W. Szostak.” Genetics 157, no. 2 (February, 2001).

Artificial heart
Artificial heart
The invention: The first successful artificial heart, the Jarvik-7, has
helped to keep patients suffering from otherwise terminal heart
disease alive while they await human heart transplants.
The people behind the invention:
Robert Jarvik (1946- ), the main inventor of the Jarvik-7
William Castle DeVries (1943- ), a surgeon at the University
of Utah in Salt Lake City
Barney Clark (1921-1983), a Seattle dentist, the first recipient of
the Jarvik-7
Early Success
The Jarvik-7 artificial heart was designed and produced by researchers
at the University of Utah in Salt Lake City; it is named for
the leader of the research team, Robert Jarvik. An air-driven pump
made of plastic and titanium, it is the size of a human heart. It is made
up of two hollow chambers of polyurethane and aluminum, each
containing a flexible plastic membrane. The heart is implanted in a
human being but must remain connected to an external air pump by
means of two plastic hoses. The hoses carry compressed air to the
heart, which then pumps the oxygenated blood through the pulmonary
artery to the lungs and through the aorta to the rest of the body.
The device is expensive, and initially the large, clumsy air compressor
had to be wheeled from room to room along with the patient.
The device was new in 1982, and that same year Barney Clark, a
dentist from Seattle, was diagnosed as having only hours to live.
His doctor, cardiac specialist William Castle DeVries, proposed surgically
implanting the Jarvik-7 heart, and Clark and his wife agreed.
The Food and Drug Administration (FDA), which regulates the use
of medical devices, had already given DeVries and his coworkers
permission to implant up to seven Jarvik-7 hearts for permanent use.
The operation was performed on Clark, and at first it seemed quite
successful. Newspapers, radio, and television reported this medical
breakthrough: the first time a severely damaged heart had been re-
45

46 / Artificial heart
William C. DeVries
William Castle DeVries did not invent the artificial heart
himself; however, he did develop the procedure to implant it.
The first attempt took him seven and a half hours, and he
needed fourteen assistants. A success, the surgery made DeVries
one of the most talked-about doctors in the world.
DeVries was born in Brooklyn, New York, in 1943. His father,
a Navy physician, was killed in action a few months later, and
his mother, a nurse, moved with her son to Utah. As a child
DeVries showed both considerable mechanical aptitude and
athletic prowess. He won an athletic scholarship to the University
of Utah, graduating with honors in 1966. He entered the
state medical school and there met Willem Kolff, a pioneer in
designing and testing artificial organs. Under Kolff’s guidance,
DeVries began performing experimental surgeries on animals
to test prototype mechanical hearts. He finished medical school
in 1970 and from 1971 until 1979 was an intern and then a resident
in surgery at the Duke University Medical Center in North
Carolina.
DeVries returned to the University of Utah as an assistant
professor of cardiovascular and thoracic surgery. In the meantime,
Robert K. Jarvik had devised the Jarvik-7 artificial heart.
DeVries experimented, implanting it in animals and cadavers
until, following approval from the Federal Drug Administration,
Barney Clark agreed to be the first test patient. He died 115
days after the surgery, having never left the hospital. Although
controversy arose over the ethics and cost of the procedure,
more artificial heart implantations followed, many by DeVries.
Long administrative delays getting patients approved for
surgery at Utah frustrated DeVries, so he moved to Humana
Hospital-Audubon in Louisville, Kentucky, in 1984 and then
took a professorship at the University of Louisville. In 1988 he
left experimentation for a traditional clinical practice. The FDA
withdrew its approval for the Jarvik-7 in 1990.
In 1999 DeVries retired from practice, but not from medicine.
The next year he joined the Army Reserve and began teaching
surgery at the Walter Reed Army Medical Center.
placed by a totally artificial heart. It seemed DeVries had proved that
an artificial heart could be almost as good as a human heart.
Soon after Clark’s surgery, DeVries went on to implant the device

in several other patients with serious heart disease. For a time, all of
them survived the surgery. As a result, DeVries was offered a position
at Humana Hospital in Louisville, Kentucky. Humana offered
to pay for the first one hundred implant operations.
The Controversy Begins
Artificial heart / 47
In the three years after DeVries’s operation on Barney Clark,
however, doubts and criticism arose. Of the people who by then had
received the plastic and metal device as a permanent replacement
for their own diseased hearts, three had died (including Clark) and
four had suffered serious strokes. The FDA asked Humana Hospital
and Symbion (the company that manufactured the Jarvik-7) for
complete, detailed histories of the artificial-heart recipients.
It was determined that each of the patients who had died or been
disabled had suffered from infection. Life-threatening infection, or
“foreign-body response,” is a danger with the use of any artificial
organ. The Jarvik-7, with its metal valves, plastic body, and Velcro
attachments, seemed to draw bacteria like a magnet—and these
bacteria proved resistant to even the most powerful antibiotics.
By 1988, researchers had come to realize that severe infection was
almost inevitable if a patient used the Jarvik-7 for a long period of
time. As a result, experts recommended that the device be used for
no longer than thirty days.
Questions of values and morality also became part of the controversy
surrounding the artificial heart. Some people thought that it
was wrong to offer patients a device that would extend their lives
but leave them burdened with hardship and pain. At times DeVries
claimed that it was worth the price for patients to be able live another
year; at other times, he admitted that if he thought a patient
would have to spend the rest of his or her life in a hospital, he would
think twice before performing the implant.
There were also questions about “informed consent”—the patient’s
understanding that a medical procedure has a high risk of
failure and may leave the patient in misery even if it succeeds.
Getting truly informed consent from a dying patient is tricky, because,
understandably, the patient is probably willing to try anything.
The Jarvik-7 raised several questions in this regard: Was the

48 / Artificial heart
ordeal worth the risk? Was the patient’s suffering justifiable? Who
should make the decision for or against the surgery: the patient, the
researchers, or a government agency?
Also there was the issue of cost. Should money be poured into expensive,
high-technology devices such as the Jarvik heart, or should
it be reserved for programs to help prevent heart disease in the first
place? Expenses for each of DeVries’s patients had amounted to
about one million dollars.
Humana’s and DeVries’s earnings were criticized in particular.
Once the first one hundred free Jarvik-7 implantations had been
performed, Humana Hospital could expect to make large amounts
of money on the surgery. By that time, Humana would have so
much expertise in the field that, though the surgical techniques
could not be patented, it was expected to have a practical monopoly.
DeVries himself owned thousands of shares of stock in Symbion.
Many people wondered whether this was ethical.
Consequences
Given all the controversies, in December of 1985 a panel of experts
recommended that the FDA allow the experiment to continue,
but only with careful monitoring. Meanwhile, cardiac transplantation
was becoming easier and more common. By the end of 1985, almost
twenty-six hundred patients in various countries had received
human heart transplants, and 76 percent of these patients had survived
for at least four years. When the demand for donor hearts exceeded
the supply, physicians turned to the Jarvik device and other
artificial hearts to help see patients through the waiting period.
Experience with the Jarvik-7 made the world keenly aware of
how far medical science still is from making the implantable permanent
mechanical heart a reality. Nevertheless, the device was a
breakthrough in the relatively new field of artificial organs. Since
then, other artificial body parts have included heart valves, blood
vessels, and inner ears that help restore hearing to the deaf.
See also Artificial blood; Artificial kidney; Blood transfusion;
Coronary artery bypass surgery; Electrocardiogram; Heart-lung
machine; Pacemaker; Velcro.

Further Reading
Artificial heart / 49
Fox, Renee C., and Judith P. Swazy. Spare Parts: Organ Replacement in
American Society. New York: Oxford University Press, 1992.
Kunin, Calvin M., Joanne J. Debbins, and Julio C. Melo. “Infectious
Complications in Four Long-Term Recipients of the Jarvik-7 Artificial
Heart.” JAMA 259 (February 12, 1988).
Kunzig, Robert. “The Beat Goes On.” Discover 21, no. 1 (January,
2000).
Lawrie, Gerald M. “Permanent Implantation of the Jarvik-7 Total
Artificial Heart: A Clinical Perspective.” JAMA 259 (February 12,
1988).

50
Artificial hormone
Artificial hormone
The invention: Synthesized oxytocin, a small polypeptide hormone
from the pituitary gland that has shown how complex polypeptides
and proteins may be synthesized and used in medicine.
The people behind the invention:
Vincent du Vigneaud (1901-1978), an American biochemist and
winner of the 1955 Nobel Prize in Chemistry
Oliver Kamm (1888-1965), an American biochemist
Sir Edward Albert Sharpey-Schafer (1850-1935), an English
physiologist
Sir Henry Hallett Dale (1875-1968), an English physiologist and
winner of the 1936 Nobel Prize in Physiology or Medicine
John Jacob Abel (1857-1938), an American pharmacologist and
biochemist
Body-Function Special Effects
In England in 1895, physician George Oliver and physiologist
Edward Albert Sharpey-Schafer reported that a hormonal extract
from the pituitary gland of a cow produced a rise in blood pressure
(a pressor effect) when it was injected into animals. In 1901, Rudolph
Magnus and Sharpey-Schafer discovered that extracts from
the pituitary also could restrict the flow of urine (an antidiuretic effect).
This observation was related to the fact that when a certain
section of the pituitary was removed surgically from an animal, the
animal excreted an abnormally large amount of urine.
In addition to the pressor and antidiuretic activities in the pituitary,
two other effects were found in 1909. Sir Henry Hallett Dale,
an English physiologist, was able to show that the extracts could
cause the uterine muscle to contract (an oxytocic effect), and Isaac
Ott and John C. Scott found that when lactating (milk-producing)
animals were injected with the extracts, milk was released from the
mammary gland.
Following the discovery of these various effects, attempts were
made to concentrate and isolate the substance or substances that

were responsible. John Jacob Abel was able to concentrate the pressor
activity at The Johns Hopkins University using heavy metal salts
and extraction with organic solvents. The results of the early work,
however, were varied. Some investigators came to the conclusion
that only one substance was responsible for all the activities, while
others concluded that two or more substances were likely to be involved.
In 1928, Oliver Kamm and his coworkers at the drug firm of
Parke, Davis and Company in Detroit reported a method for the
separation of the four activities into two chemical fractions with
high potency. One portion contained most of the pressor and antidiuretic
activities, while the other contained the uterine-contracting
and milk-releasing activities. Over the years, several names have
been used for the two substances responsible for the effects. The generic
name “vasopressin” generally has become the accepted term
for the substance causing the pressor and antidiuretic effects, while
the name “oxytocin” has been used for the other two effects. The
two fractions that Kamm and his group had prepared were pure
enough for the pharmaceutical firm to make them available for
medical research related to obstetrics, surgical shock, and diabetes
insipidus.
A Complicated Synthesis
Artificial hormone / 51
The problem of these hormones and their nature interested Vincent
du Vigneaud at the George Washington University School of
Medicine. Working with Kamm, he was able to show that the sulfur
content of both the oxytocin and the vasopressin fractions was a result
of the amino acid cystine. This helped to strengthen the concept
that these hormones were polypeptide, or proteinlike, substances.
Du Vigneaud and his coworkers next tried to find a way of purifying
oxytocin and vasopressin. This required not only the separation
of the hormones themselves but also the separation from other impurities
present in the preparations.
During World War II (1939-1945) and shortly thereafter, other
techniques were developed that would give du Vigneaud the tools
he needed to complete the job of purifying and characterizing
the two hormonal factors. One of the most important was the

52 / Artificial hormone
countercurrent distribution method of chemist Lyman C. Craig at
the Rockefeller Institute. Craig had developed an apparatus that
could do multiple extractions, making possible separations of substances
with similar properties. Du Vigneaud had used this technique
in purifying his synthetic penicillin, and when he returned to
the study of oxytocin and vasopressin in 1946, he used it on his purest
preparations. The procedure worked well, and milligram quantities
of pure oxytocin were available in 1949 for chemical characterization.
Using the available techniques, Vigneaud and his coworkers
were able to determine the structure of oxytocin. It was du Vigneaud’s
goal to make synthetic oxytocin by duplicating the structure
his group had worked out. Eventually, du Vigneaud’s synthetic
oxytocin was obtained and the method published in the Journal of
the American Chemical Society in 1953.
Du Vigneaud’s oxytocin was next tested against naturally occurring
oxytocin, and the two forms were found to act identically in every
respect. In the final test, the synthetic form was found to induce
labor when given intravenously to women about to give birth. Also,
when microgram quantities of oxytocin were given intravenously
to women who had recently given birth, milk was released from the
mammary gland in less than a minute.
Consequences
The work of du Vigneaud and his associates demonstrated for
the first time that it was possible to synthesize peptides that have
properties identical to the natural ones and that these can be useful
in certain medical conditions. Oxytocin has been used in the last
stages of labor during childbirth. Vasopressin has been used in the
treatment of diabetes insipidus, when an individual has an insufficiency
in the natural hormone, much as insulin is used by persons
having diabetes mellitus.
After receiving the Nobel Prize in Chemistry in 1955, du Vigneaud
continued his work on synthesizing chemical variations of the two
hormones. By making peptides that differed from oxytocin and
vasopressin by one or more amino acids, it was possible to study how
the structure of the peptide was related to its physiological activity.

After the structure of insulin and some of the smaller proteins
were determined, they, too, were synthesized, although with greater
difficulty. Other methods of carrying out the synthesis of peptides
and proteins have been developed and are used today. The production
of biologically active proteins, such as insulin and growth hormone,
has been made possible by efficient methods of biotechnology.
The genes for these proteins can be put inside microorganisms,
which then make them in addition to their own proteins. The microorganisms
are then harvested and the useful protein hormones isolated
and purified.
See also Abortion pill; Artificial blood; Birth control pill; Genetically
engineered insulin; Pap test.
Further Reading
Artificial hormone / 53
Basa, Channa, and G. M. Anantharamaiah. Peptides: Design, Synthesis,
and Biological Activity. Boston: Birkauser, 1994.
Bodanszky, Miklos. “Vincent du Vigneaud, 1901-1978.” Nature 279,
no. 5710 (1979).
Vigneud, Vincent du. “A Trail of Sulfur Research from Insulin to
Oxytocin” [Nobel lecture]. In Chemistry, 1942-1962. River Edge,
N.J.: World Scientific, 1999.

54
Artificial insemination
Artificial insemination
The invention: Practical techniques for the artificial insemination
of farm animals that have revolutionized livestock breeding practices
throughout the world.
The people behind the invention:
Lazzaro Spallanzani (1729-1799), an Italian physiologist
Ilya Ivanovich Ivanov (1870-1932), a Soviet biologist
R. W. Kunitsky, a Soviet veterinarian
Reproduction Without Sex
The tale is told of a fourteenth-century Arabian chieftain who
sought to improve his mediocre breed of horses. Sneaking into the
territory of a neighboring hostile tribe, he stimulated a prize stallion
to ejaculate into a piece of cotton. Quickly returning home, he
inserted this cotton into the vagina of his own mare, who subsequently
gave birth to a high-quality horse. This may have been the
first case of “artificial insemination,” the technique by which semen
is introduced into the female reproductive tract without sexual
contact.
The first scientific record of artificial insemination comes from Italy
in the 1770’s. Lazzaro Spallanzani was one of the foremost physiologists
of his time, well known for having disproved the theory of
spontaneous generation, which states that living organisms can
spring “spontaneously” from lifeless matter. There was some disagreement
at that time about the basic requirements for reproduction
in animals. It was unclear if the sex act was necessary for an embryo
to develop, or if it was sufficient that the sperm and eggs come
into contact. Spallanzani began by studying animals in which union
of the sperm and egg normally takes place outside the body of the
female. He stimulated males and females to release their sperm and
eggs, then mixed these sex cells in a glass dish. In this way, he produced
young frogs, toads, salamanders, and silkworms.
Next, Spallanzani asked whether the sex act was also unnecessary
for reproduction in those species in which fertilization nor-

mally takes place inside the body of the female. He collected semen
that had been ejaculated by a male spaniel and, using a syringe, injected
the semen into the vagina of a female spaniel in heat. Two
months later, she delivered a litter of three pups, which bore some
resemblance to both the mother and the male that had provided the
sperm.
It was in animal breeding that Spallanzani’s techniques were to
have their most dramatic application. In the 1880’s, an English dog
breeder, Sir Everett Millais, conducted several experiments on artificial
insemination. He was interested mainly in obtaining offspring
from dogs that would not normally mate with one another because
of difference in size. He followed Spallanzani’s methods to produce
a cross between a short, low, basset hound and the much larger
bloodhound.
Long-Distance Reproduction
Artificial insemination / 55
Ilya Ivanovich Ivanov was a Soviet biologist who was commissioned
by his government to investigate the use of artificial insemination
on horses. Unlike previous workers who had used artificial
insemination to get around certain anatomical barriers to fertilization,
Ivanov began the use of artificial insemination to reproduce
thoroughbred horses more effectively. His assistant in this work
was the veterinarian R. W. Kunitsky.
In 1901, Ivanov founded the Experimental Station for the Artificial
Insemination of Horses. As its director, he embarked on a series
of experiments to devise the most efficient techniques for breeding
these animals. Not content with the demonstration that the technique
was scientifically feasible, he wished to ensure further that it
could be practiced by Soviet farmers.
If sperm from a male were to be used to impregnate females in
another location, potency would have to be maintained for a long
time. Ivanov first showed that the secretions from the sex glands
were not required for successful insemination; only the sperm itself
was necessary. He demonstrated further that if a testicle were removed
from a bull and kept cold, the sperm would remain alive.
More useful than preservation of testicles would be preservation
of the ejaculated sperm. By adding certain salts to the sperm-

56 / Artificial insemination
containing fluids, and by keeping these at cold temperatures, Ivanov
was able to preserve sperm for long periods.
Ivanov also developed instruments to inject the sperm, to hold
the vagina open during insemination, and to hold the horse in place
during the procedure. In 1910, Ivanov wrote a practical textbook
with technical instructions for the artificial insemination of horses.
He also trained some three hundred veterinary technicians in the
use of artificial insemination, and the knowledge he developed
quickly spread throughout the Soviet Union. Artificial insemination
became the major means of breeding horses.
Until his death in 1932, Ivanov was active in researching many
aspects of the reproductive biology of animals. He developed methods
to treat reproductive diseases of farm animals and refined
methods of obtaining, evaluating, diluting, preserving, and disinfecting
sperm. He also began to produce hybrids between wild and
domestic animals in the hope of producing new breeds that would
be able to withstand extreme weather conditions better and that
would be more resistant to disease. His crosses included hybrids of
ordinary cows with aurochs, bison, and yaks, as well as some more
exotic crosses of zebras with horses.
Ivanov also hoped to use artificial insemination to help preserve
species that were in danger of becoming extinct. In 1926, he led an
expedition to West Africa to experiment with the hybridization of
different species of anthropoid apes.
Impact
The greatest beneficiaries of artificial insemination have been
dairy farmers. Some bulls are able to sire genetically superior cows
that produce exceptionally large volumes of milk. Under natural
conditions, such a bull could father at most a few hundred offspring
in its lifetime. Using artificial insemination, a prize bull can inseminate
ten to fifteen thousand cows each year. Since frozen sperm may
be purchased through the mail, this also means that dairy farmers
no longer need to keep dangerous bulls on the farm. Artificial insemination
has become the main method of reproduction of dairy
cows, with about 150 million cows (as of 1992) produced this way
throughout the world.

In the 1980’s, artificial insemination gained added importance as
a method of breeding rare animals. Animals kept in zoo cages, animals
that are unable to take part in normal mating, may still produce
sperm that can be used to inseminate a female artificially.
Some species require specific conditions of housing or diet for normal
breeding to occur, conditions not available in all zoos. Such animals
can still reproduce using artificial insemination.
See also Abortion pill; Amniocentesis; Artificial chromosome;
Birth control pill; Cloning; Genetic “fingerprinting”; Genetically engineered
insulin; In vitro plant culture; Rice and wheat strains; Synthetic
DNA.
Further Reading
Artificial insemination / 57
Bearden, Henry Joe, and John W. Fuquay. Applied Animal Reproduction.
5th ed. Upper Saddle River, N.J.: Prentice Hall, 2000.
Foote, Robert H. Artificial Insemination to Cloning: Tracing Fifty Years
of Research. Ithaca, N.Y.: Cornell University Press, 1998.
Hafez, Elsayed Saad Eldin. Reproduction in Farm Animals. 6th ed.
Philadelphia: Lea and Febiger, 1993.
Herman, Harry August. Improving Cattle by the Millions: NAAB and
the Development and Worldwide Application of Artificial Insemination.
Columbia: University of Missouri Press, 1981.

58
Artificial kidney
Artificial kidney
The invention: A machine that removes waste end-products and
poisons out of the blood when human kidneys are not working
properly.
The people behind the invention:
John Jacob Abel (1857-1938), a pharmacologist and biochemist
known as the “father of American pharmacology”
Willem Johan Kolff (1911- ), a Dutch American clinician who
pioneered the artificial kidney and the artificial heart
Cleansing the Blood
In the human body, the kidneys are the dual organs that remove
waste matter from the bloodstream and send it out of the system as
urine. If the kidneys fail to work properly, this cleansing process
must be done artifically—such as by a machine.
John Jacob Abel was the first professor of pharmacology at Johns
Hopkins University School of Medicine. Around 1912, he began to
study the by-products of metabolism that are carried in the blood.
This work was difficult, he realized, because it was nearly impossible
to detect even the tiny amounts of the many substances in blood.
Moreover, no one had yet developed a method or machine for taking
these substances out of the blood.
In devising a blood filtering system, Abel understood that he
needed a saline solution and a membrane that would let some substances
pass through but not others. Working with Leonard Rowntree
and Benjamin B. Turner, he spent nearly two years figuring out
how to build a machine that would perform dialysis—that is, remove
metabolic by-products from blood. Finally their efforts succeeded.
The first experiments were performed on rabbits and dogs. In
operating the machine, the blood leaving the patient was sent flowing
through a celloidin tube that had been wound loosely around a
drum. An anticlotting substance (hirudin, taken out of leeches) was
added to blood as the blood flowed through the tube. The drum,
which was immersed in a saline and dextrose solution, rotated

slowly. As blood flowed through the immersed tubing, the pressure
of osmosis removed urea and other substances, but not the plasma
or cells, from the blood. The celloidin membranes allowed oxygen
to pass from the saline and dextrose solution into the blood, so that
purified, oxygenated blood then flowed back into the arteries.
Abel studied the substances that his machine had removed from
the blood, and he found that they included not only urea but also
free amino acids. He quickly realized that his machine could be useful
for taking care of people whose kidneys were not working properly.
Reporting on his research, he wrote, “In the hope of providing a
substitute in such emergencies, which might tide over a dangerous
crisis...amethod has been devised by which the blood of a living
animal may be submitted to dialysis outside the body, and again returned
to the natural circulation.” Abel’s machine removed large
quantities of urea and other poisonous substances fairly quickly, so
that the process, which he called “vividiffusion,” could serve as an
artificial kidney during cases of kidney failure.
For his physiological research, Abel found it necessary to remove,
study, and then replace large amounts of blood from living
animals, all without dissolving the red blood cells, which carry oxygen
to the body’s various parts. He realized that this process, which
he called “plasmaphaeresis,” would make possible blood banks,
where blood could be stored for emergency use.
In 1914, Abel published these two discoveries in a series of three
articles in the Journal of Pharmacology and Applied Therapeutics, and
he demonstrated his techniques in London, England, and Groningen,
The Netherlands. Though he had suggested that his techniques
could be used for medical purposes, he himself was interested
mostly in continuing his biochemical research. So he turned to
other projects in pharmacology, such as the crystallization of insulin,
and never returned to studying vividiffusion.
Refining the Technique
Artificial kidney / 59
Georg Haas, a German biochemist working in Giessen, West Germany,
was also interested in dialysis; in 1915, he began to experiment
with “blood washing.” After reading Abel’s 1914 writings,
Haas tried substituting collodium for the celloidin that Abel had used

60 / Artificial kidney
as a filtering membrane and using commercially prepared heparin
instead of the homemade hirudin Abel had used to prevent blood
clotting. He then used this machine on a patient and found that it
showed promise, but he knew that many technical problems had to
be worked out before the procedure could be used on many patients.
In 1937, Willem Johan Kolff was a young physician at Groningen.
He felt sad to see patients die from kidney failure, and he wanted to
find a way to cure others. Having heard his colleagues talk about
the possibility of using dialysis on human patients, he decided to
build a dialysis machine.
Kolff knew that cellophane was an excellent membrane for dialyzing,
and that heparin was a good anticoagulant, but he also realized
that his machine would need to be able to treat larger volumes
of blood than Abel’s and Haas’s had. During World War II (1939-
John Jacob Abel
Born in 1857, John Jacob Abel grew up in Cleveland, Ohio,
and then attended the University of Michigan. He graduated in
1883 and studied for six years in Germany, which boasted the
finest medical researchers of the times. He received a medical
degree in 1888 in Strasbourg, transferred to Vienna, Austria, for
more clinical experience, and then returned to the United States
in 1891 to teach pharmacology at the University of Michigan.
He had to organize his own laboratory, journal, and course of
instruction. His efforts attracted the notice of Johns Hopkins
University, which then had the nation’s most progressive medical
school. In 1893 Abel moved there and became the first
American to hold the title of professor of pharmacology. He remained
at Johns Hopkins until his retirement in 1932.
His biochemical research illuminated the complex interaction
in the endocrine system. He isolated epinephrine (adrenaline),
used his artificial kidney apparatus to demonstrate the
presence of amino acids in the blood, and investigated pituitary
gland hormones and insulin.
Abel died in 1938, but his influence did not. His many students
took Abel’s interest in the biochemical basis of pharmacology
to other universities and commercial laboratories, modernizing
American drug research.

1945), with the help of the director of a nearby enamel factory, Kolff
built an artificial kidney that was first tried on a patient on March
17, 1943. Between March, 1943, and July 21, 1944, Kolff used his secretly
constructed dialysis machines on fifteen patients, of whom
only one survived. He published the results of his research in Acta
Medica Scandinavica. Even though most of his patients had not survived,
he had collected information and developed the technique
until he was sure dialysis would eventually work.
Kolff brought machines to Amsterdam and The Hague and encouraged
other physicians to try them; meanwhile, he continued to
study blood dialysis and to improve his machines. In 1947, he
brought improved machines to London and the United States. By
the time he reached Boston, however, he had given away all of
his machines. He did, however, explain the technique to John P.
Merrill, a physician at the Harvard Medical School, who soon became
the leading American developer of kidney dialysis and kidney-transplant
surgery.
Kolff himself moved to the United States, where he became an
expert not only in artificial kidneys but also in artificial hearts. He
helped develop the Jarvik-7 artificial heart (named for its chief inventor,
Robert Jarvik), which was implanted in a patient in 1982.
Impact
Artificial kidney / 61
Abel’s work showed that the blood carried some substances that
had not been previously known and led to the development of the
first dialysis machine for humans. It also encouraged interest in the
possibility of organ transplants.
After World War II, surgeons had tried to transplant kidneys from
one animal to another, but after a few days the recipient began to reject
the kidney and die. In spite of these failures, researchers in Europe and
America transplanted kidneys in several patients, and they used artificial
kidneys to take care of the patients who were waiting for transplants.
In 1954, Merrill—to whom Kolff had demonstrated an artificial
kidney—successfully transplanted kidneys in identical twins.
After immunosuppressant drugs (used to prevent the body
from rejecting newly transplanted tissue) were discovered in 1962,
transplantation surgery became much more practical. After kid-

62 / Artificial kidney
ney transplants became common, the artificial kidney became simply
a way of keeping a person alive until a kidney donor could be
found.
See also Artificial blood; Artificial heart; Blood transfusion; Genetically
engineered insulin; Reserpine.
Further Reading
Cogan, Martin G., Patricia Schoenfeld, and Frank A. Gotch. Introduction
to Dialysis. 2d ed. New York: Churchill Livingstone, 1991.
DeJauregui, Ruth. One Hundred Medical Milestones That Shaped World
History. San Mateo, Calif.: Bluewood Books, 1998.
Noordwijk, Jacob van. Dialysing for Life: The Development of the Artificial
Kidney. Boston: Kluwer Academic Publishers, 2001.

Artificial satellite
Artificial satellite
The invention: Sputnik I, the first object put into orbit around the
earth, which began the exploration of space.
The people behind the invention:
Sergei P. Korolev (1907-1966), a Soviet rocket scientist
Konstantin Tsiolkovsky (1857-1935), a Soviet schoolteacher and
the founder of rocketry in the Soviet Union
Robert H. Goddard (1882-1945), an American scientist and the
founder of rocketry in the United States
Wernher von Braun (1912-1977), a German who worked on
rocket projects
Arthur C. Clarke (1917- ), the author of more than fifty
books and the visionary behind telecommunications
satellites
A Shocking Launch
In Russian, sputnik means “satellite” or “fellow traveler.” On October
4, 1957, Sputnik 1, the first artificial satellite to orbit Earth, was
placed into successful orbit by the Soviet Union. The launch of this
small aluminum sphere, 0.58 meter in diameter and weighing 83.6
kilograms, opened the doors to the frontiers of space.
Orbiting Earth every 96 minutes, at 28,962 kilometers per hour,
Sputnik 1 came within 215 kilometers of Earth at its closest point and
939 kilometers away at its farthest point. It carried equipment to
measure the atmosphere and to experiment with the transmission
of electromagnetic waves from space. Equipped with two radio
transmitters (at different frequencies) that broadcast for twenty-one
days, Sputnik 1 was in orbit for ninety-two days, until January 4,
1958, when it disintegrated in the atmosphere.
Sputnik 1 was launched using a Soviet intercontinental ballistic
missile (ICBM) modified by Soviet rocket expert Sergei P. Korolev.
After the launch of Sputnik 2, less than a month later, Chester
Bowles, a former United States ambassador to India and Nepal,
wrote: “Armed with a nuclear warhead, the rocket which launched
63

64 / Artificial satellite
Sergei P. Korolev
Sergei P. Korolev’s rocket launched the Space Age: Sputnik I
climbed into outer space aboard one of his R-7 missiles. Widely
considered the Soviet Union’s premiere rocket scientist, he almost
died in Joseph Stalin’s infamous Siberian prison camps
before he could build the launchers that made his country a military
superpower and pioneer of space exploration.
Born in 1907, Korolev studied aeronautical engineering at
the Kiev Polytechnic Institute. Upon graduation he helped found
the Group for Investigation of Reactive Motion, which in the
early 1930’s tested liquid-fuel rockets. His success attracted the
military’s attention. It created the Reaction Propulsion Scientific
Research Institute for him, and he was on the verge of testing
a rocket-propelled airplane when he was arrested during a
political purge in 1937 and sent as a prison laborer to the
Kolyma gold mines. After Germany attacked Russia in World
War II, Korolev was transferred to a prison research institute to
help develop advanced aircraft.
After World War II, rehabilitated in the eyes of the Soviet authorities,
Korolev was placed in charge of long-range ballistic
missile research. In 1953 he began to build the R-7 intercontinental
ballistic missile (ICBM). While other design bureaus concentrated
on developing the ICBM into a Cold War weapon,
Korolev built rockets that explored the Moon with probes. His
goal was to send cosmonauts there too. With his designs and
guidance, the Soviet space program proved that human space
flight was possible in 1961, and so in 1962 he began development
of the N-1, a booster that like the American Saturn V
was powerful enough to send a crewed vehicle to the Moon.
Tragically, Korolev died following minor surgery in 1966. The
N-1 project was cancelled in 1971, along with Russian dreams of
settling its citizens on the Moon.
Sputnik 1 could destroy New York, Chicago, or Detroit 18 minutes
after the button was pushed in Moscow.”
Although the launch of Sputnik 1 came as a shock to the general
public, it came as no surprise to those who followed rocketry. In
June, 1957, the United States Air Force had issued a nonclassified
memo stating that there was “every reason to believe that the Rus-

sian satellite shot would be made on the hundredth anniversary” of
Konstantin Tsiolkovsky’s birth.
Thousands of Launches
Artificial satellite / 65
Rockets have been used since at least the twelfth century, when
Europeans and the Chinese were using black powder devices. In
1659, the Polish engineer Kazimir Semenovich published his Roketten
für Luft und Wasser (rockets for air and water), which had a drawing
of a three-stage rocket. Rockets were used and perfected for warfare
during the nineteenth and twentieth centuries. Nazi Germany’s V-2
rocket (thousands of which were launched by Germany against England
during the closing years of World War II) was the model for
American and Soviet rocket designers between 1945 and 1957. In
the Soviet Union, Tsiolkovsky had been thinking about and writing
about space flight since the last decade of the nineteenth century,
and in the United States, Robert H. Goddard had been thinking
about and experimenting with rockets since the first decade of the
twentieth century.
Wernher von Braun had worked on rocket projects for Nazi Germany
during World War II, and, as the war was ending in May, 1945,
von Braun and several hundred other people involved in German
rocket projects surrendered to American troops in Europe. Hundreds
of other German rocket experts ended up in the Soviet Union
to continue with their research. Tom Bower pointed out in his book
The Paperclip Conspiracy: The Hunt for the Nazi Scientists (1987)—so
named because American “recruiting officers had identified [Nazi]
scientists to be offered contracts by slipping an ordinary paperclip
onto their files”—that American rocketry research was helped
tremendously by Nazi scientists who switched sides after World
War II.
The successful launch of Sputnik 1 convinced people that space
travel was no longer simply science fiction. The successful launch of
Sputnik 2 on November 3, 1957, carrying the first space traveler, a
dog named Laika (who was euthanized in orbit because there were
no plans to retrieve her), showed that the launch of Sputnik 1 was
only the beginning of greater things to come.

66 / Artificial satellite
Consequences
After October 4, 1957, the Soviet Union and other nations launched
more experimental satellites. On January 31, 1958, the United
States sent up Explorer 1, after failing to launch a Vanguard satellite
on December 6, 1957.
Arthur C. Clarke, most famous for his many books of science fiction,
published a technical paper in 1945 entitled “Extra-Terrestrial
Relays: Can Rocket Stations Give World-Wide Radio Coverage?” In
that paper, he pointed out that a satellite placed in orbit at the correct
height and speed above the equator would be able to hover over
the same spot on Earth. The placement of three such “geostationary”
satellites would allow radio signals to be transmitted around
the world. By the 1990’s, communications satellites were numerous.
In the first twenty-five years after Sputnik 1 was launched, from
1957 to 1982, more than two thousand objects were placed into various
Earth orbits by more than twenty-four nations. On the average,
something was launched into space every 3.82 days for this twentyfive-year
period, all beginning with Sputnik 1.
See also Communications satellite; Cruise missile; Rocket; V-2
rocket; Weather satellite.
Further Reading
Dickson, Paul. Sputnik: The Shock of the Century. New York: Walker,
2001.
Heppenheimer, T. A. Countdown: A History of Space Flight. New York:
John Wiley & Sons, 1997.
Logsdon, John M., Roger D. Launius, and Robert W. Smith. Reconsidering
Sputnik: Forty Years Since the Soviet Satellite. Australia:
Harwood Academic, 2000.

Aspartame
Aspartame
The invention: An artificial sweetener with a comparatively natural
taste widely used in carbonated beverages.
The people behind the invention:
Arthur H. Hayes, Jr. (1933- ), a physician and commissioner
of the U.S. Food and Drug Administration (FDA)
James M. Schlatter (1942- ), an American chemist
Michael Sveda (1912- ), an American chemist and inventor
Ludwig Frederick Audrieth (1901- ), an American chemist
and educator
Ira Remsen (1846-1927), an American chemist and educator
Constantin Fahlberg (1850-1910), a German chemist
Sweetness Without Calories
People have sweetened food and beverages since before recorded
history. The most widely used sweetener is sugar, or sucrose. The
only real drawback to the use of sucrose is that it is a nutritive sweetener:
In addition to adding a sweet taste, it adds calories. Because
sucrose is readily absorbed by the body, an excessive amount can be
life-threatening to diabetics. This fact alone would make the development
of nonsucrose sweeteners attractive.
There are three common nonsucrose sweeteners in use around
the world: saccharin, cyclamates, and aspartame. Saccharin was the
first of this group to be discovered, in 1879. Constantin Fahlberg
synthesized saccharin based on the previous experimental work of
Ira Remsen using toluene (derived from petroleum). This product
was found to be three hundred to five hundred times as sweet as
sugar, although some people could detect a bitter aftertaste.
In 1944, the chemical family of cyclamates was discovered by
Ludwig Frederick Audrieth and Michael Sveda. Although these
compounds are only thirty to eighty times as sweet as sugar, there
was no detectable aftertaste. By the mid-1960’s, cyclamates had
resplaced saccharin as the leading nonnutritive sweetener in the
United States. Although cyclamates are still in use throughout the
67

68 / Aspartame
world, in October, 1969, FDA removed them from the list of approved
food additives because of tests that indicated possible health
hazards.
A Political Additive
Aspartame is the latest in artificial sweeteners that are derived
from natural ingredients—in this case, two amino acids, one from
milk and one from bananas. Discovered by accident in 1965 by
American chemist James M. Schlatter when he licked his fingers
during an experiment, aspartame is 180 times as sweet as sugar. In
1974, the FDA approved its use in dry foods such as gum and cereal
and as a sugar replacement.
Shortly after its approval for this limited application, the FDA
held public hearings on the safety concerns raised by John W. Olney,
a professor of neuropathology at Washington University in St. Louis.
There was some indication that aspartame, when combined with
the common food additive monosodium glutamate, caused brain
damage in children. These fears were confirmed, but the risk of
brain damage was limited to a small percentage of individuals with
a rare genetic disorder. At this point, the public debate took a political
turn: Senator William Proxmire charged FDA Commissioner Alexander
M. Schmidt with public misconduct. This controversy resulted
in aspartame being taken off the market in 1975.
In 1981, the new FDA commissioner, Arthur H. Hayes, Jr., resapproved
aspartame for use in the same applications: as a tabletop
sweetener, as a cold-cereal additive, in chewing gum, and for other
miscellaneous uses. In 1983, the FDA approved aspartame for use in
carbonated beverages, its largest application to date. Later safety
studies revealed that children with a rare metabolic disease, phenylketonuria,
could not ingest this sweetener without severe health
risks because of the presence of phenylalanine in aspartame. This
condition results in a rapid buildup in phenylalanine in the blood.
Laboratories simulated this condition in rats and found that high
doses of aspartame inhibited the synthesis of dopamine, a neurotransmitter.
Once this happens, an increase in the frequency of seizures
can occur. There was no direct evidence, however, that aspartame
actually caused seizures in these experiments.

Many other compounds are being tested for use as sugar replacements,
the sweetest being a relative of aspartame. This compound is
seventeen thousand to fifty-two thousand times sweeter than sugar.
Impact
The business fallout from the approval of a new low-calorie
sweetener occurred over a short span of time. In 1981, sales of this
artificial sweetener by G. D. Searle and Company were $74 million.
In 1983, sales rose to $336 million and exceeded half a billion dollars
the following year. These figures represent sales of more than 2,500
tons of this product. In 1985, 3,500 tons of aspartame were consumed.
Clearly, this product’s introduction was a commercial success
for Searle. During this same period, the percentage of reducedcalorie
carbonated beverages containing saccharin declined from
100 percent to 20 percent in an industry that had $4 billion in sales.
Universally, consumers preferred products containing aspartame;
the bitter aftertaste of saccharin was rejected in favor of the new, less
powerful sweetener.
There is a trade-off in using these products. The FDA found evidence
linking both saccharin and cyclamates to an elevated incidence
of cancer. Cyclamates were banned in the United States for
this reason. Public resistance to this measure caused the agency to
back away from its position. The rationale was that, compared to
other health risks associated with the consumption of sugar (especially
for diabetics and overweight persons), the chance of getting
cancer was slight and therefore a risk that many people would
choose to ignore. The total domination of aspartame in the sweetener
market seems to support this assumption.
See also Cyclamate; Genetically engineered insulin.
Further Reading
Aspartame / 69
Blaylock, Russell L. Excitotoxins: The Taste That Kills. Santa Fe,
N.Mex.: Health Press, 1998.
Hull, Janet Starr. Sweet Poison: How the World’s Most Popular Artificial
Sweetener Is Killing Us—My Story. Far Hills, N.J.: New
Horizon Press, 1999.

70 / Aspartame
Roberts, Hyman Jacob. Aspartame (NutraSweet®): Is It Safe? Philadelphia:
Charles Press, 1990.
Stegink, Lewis D., and Lloyd J. Filer, Aspartame: Physiology and Biochemistry.
New York: M. Dekker, 1984.
Stoddard, Mary Nash. Deadly Deception: Story of Aspartame, Shocking
Expose of the World’s Most Controversial Sweetener. Dallas: Odenwald
Press, 1998.

Assembly line
Assembly line
The invention: A manufacturing technique pioneered in the automobile
industry by Henry Ford that lowered production costs
and helped bring automobile ownership within the reach of millions
of Americans in the early twentieth century.
The people behind the invention:
Henry Ford (1863-1947), an American carmaker
Eli Whitney (1765-1825), an American inventor
Elisha King Root (1808-1865), the developer of division of labor
Oliver Evans (1755-1819), the inventor of power conveyors
Frederick Winslow Taylor (1856-1915), an efficiency engineer
A Practical Man
Henry Ford built his first “horseless carriage” by hand in his
home workshop in 1896. In 1903, the Ford Motor Company was
born. Ford’s first product, the Model A, sold for less than one thousand
dollars, while other cars at that time were priced at five to ten
thousand dollars each. When Ford and his partners tried, in 1905, to
sell a more expensive car, sales dropped. Then, in 1907, Ford decided
that the Ford Motor Company would build “a motor car for
the great multitude.” It would be called the Model T.
The Model T came out in 1908 and was everything that Henry Ford
said it would be. Ford’s Model T was a low-priced (about $850), practical
car that came in one color only: black. In the twenty years during
which the Model T was built, the basic design never changed. Yet the
price of the Model T, or “Tin Lizzie,” as it was affectionately called,
dropped over the years to less than half that of the original Model T. As
the price dropped, sales increased, and the Ford Motor Company
quickly became the world’s largest automobile manufacturer.
The last of more than 15 million Model T’s was made in 1927. Although
it looked and drove almost exactly like the first Model T,
these two automobiles were built in an entirely different way. The
first was custom-built, while the last came off an assembly line.
At first, Ford had built his cars in the same way everyone else
71

72 / Assembly line
did: one at a time. Skilled mechanics would work on a car from start
to finish, while helpers and runners brought parts to these highly
paid craftsmen as they were needed. After finishing one car, the mechanics
and their helpers would begin the next.
The Quest for Efficiency
Custom-built products are good when there is little demand and
buyers are willing to pay the high labor costs. This was not the case
with the automobile. Ford realized that in order to make a large
number of quality cars at a low price, he had to find a more efficient
way to build cars. To do this, he looked to the past and the work of
others. He found four ideas: interchangeable parts, continuous flow,
division of labor, and elimination of wasted motion.
Eli Whitney, the inventor of the cotton gin, was the first person to
use interchangeable parts successfully in mass production. In 1798, the
United States government asked Whitney to make several thousand
muskets in two years. Instead of finding and hiring gunsmiths to make
the muskets by hand, Whitney used most of his time and money to design
and build special machines that could make large numbers of
Model-T assembly line in the Ford Motor Company’s Highland Park Factory. (Library
of Congress)

Assembly line / 73
identical parts—one machine for each part that was needed to build a
musket. These tools, and others Whitney made for holding, measuring,
and positioning the parts, made it easy for semiskilled, and even
unskilled, workers to build a large number of muskets.
Production can be made more efficient by carefully arranging the
different stages of production to create a “continuous flow.” Ford
borrowed this idea from at least two places: the meat-packing
houses of Chicago and an automatic grain mill run by Oliver Evans.
Ford’s idea for a moving assembly line came from Chicago’s
great meat-packing houses in the late 1860’s. Here, the bodies of animals
were moved along an overhead rail past a number of workers,
each of whom made a certain cut, or handled one part of the packing
job. This meant that many animals could be butchered and packaged
in a single day.
Ford looked to Oliver Evans for an automatic conveyor system.
In 1783, Evans had designed and operated an automatic grain mill
that could be run by only two workers. As one worker poured grain
into a funnel-shaped container, called a “hopper,” at one end of the
mill, a second worker filled sacks with flour at the other end. Everything
in between was done automatically, as Evans’s conveyors
passed the grain through the different steps of the milling process
without any help.
The idea of “division of labor” is simple: When one complicated
job is divided into several easier jobs, some things can be made
faster, with fewer mistakes, by workers who need fewer skills than
ever before. Elisha King Root had used this principle to make the famous
Colt “Six-Shooter.” In 1849, Root went to work for Samuel
Colt at his Connecticut factory and proved to be a manufacturing
genius. By dividing the work into very simple steps, with each step
performed by one worker, Root was able to make many more guns
in much less time.
Before Ford applied Root’s idea to the making of engines, it took
one worker one day to make one engine. By breaking down the
complicated job of making an automobile engine into eighty-four
simpler jobs, Ford was able to make the process much more efficient.
By assigning one person to each job, Ford’s company was able
to make 352 engines per day—an increase of more than 400 percent.
Frederick Winslow Taylor has been called the “original efficiency

74 / Assembly line
Henry Ford
Henry Ford (1863-1947) was more of a synthesizer and innovator
than an inventor. Others invented the gasoline-powered
automobile and the techniques of mass production, but it was
Ford who brought the two together. The result was the assembly
line-produced Model T that the Ford Motor Company
turned out in the millions from 1908 until 1927. And it changed
America profoundly.
Ford’s idea was to lower production costs enough so that
practically everyone could afford a car, not just the wealthy. He
succeeded brilliantly. The first Model T’s cost $850, rock bottom
for the industry, and by 1927 the price was down to $290. Americans
bought them up like no other technological marvel in the
nation’s history. For years, out of every one hundred cars on the
road almost forty of them were Model T’s. The basic version
came with nothing on the dash board but an ignition switch,
and the cars were quirky—so much so that an entire industry
grew up to outfit them for the road and make sure they stayed
running. Even then, they could only go up steep slopes backwards,
and starting them was something of an art.
Americans took the Model T to heart, affectionately nicknaming
it the flivver and Tin Lizzie. This “democratization of
the automobile,” as Ford called it, not only gave common people
modern transportation and made them more mobile than
every before; it started the American love affair with the car.
Even after production stopped in 1927, the Model T Ford remained
the archetype of American automobiles. As the great
essayist E. B. White wrote in “Farewell My Lovely” (1936), his
eulogy for the Model T, “…to a few million people who grew up
with it, the old Ford practically was the American scene.”
expert.” His idea was that inefficiency was caused by wasted time
and wasted motion. So Taylor studied ways to eliminate wasted
motion. He proved that, in the long run, doing a job too quickly was
as bad as doing it too slowly. “Correct speed is the speed at which
men can work hour after hour, day after day, year in and year out,
and remain continuously in good health,” he said. Taylor also studied
ways to streamline workers’ movements. In this way, he was
able to keep wasted motion to a minimum.

Impact
The changeover from custom production to mass production
was an evolution rather than a revolution. Henry Ford applied the
four basic ideas of mass production slowly and with care, testing
each new idea before it was used. In 1913, the first moving assembly
line for automobiles was being used to make Model T’s. Ford was
able to make his Tin Lizzies faster than ever, and his competitors
soon followed his lead. He had succeeded in making it possible for
millions of people to buy automobiles.
Ford’s work gave a new push to the Industrial Revolution. It
showed Americans that mass production could be used to improve
quality, cut the cost of making an automobile, and improve profits.
In fact, the Model T was so profitable that in 1914 Ford was able to
double the minimum daily wage of his workers, so that they too
could afford to buy Tin Lizzies.
Although Americans account for only about 6 percent of the
world’s population, they now own about 50 percent of its wealth.
There are more than twice as many radios in the United States as
there are people. The roads are crowded with more than 180 million
automobiles. Homes are filled with the sounds and sights emitting
from more than 150 million television sets. Never have the people of
one nation owned so much. Where did all the products—radios,
cars, television sets—come from? The answer is industry, which still
depends on the methods developed by Henry Ford.
See also CAD/CAM; Color television; Interchangeable parts;
Steelmaking process.
Further Reading
Assembly line / 75
Abernathy, William, Kim Clark, and Alan Kantrow. Industrial Renaissance.
New York: Basic Books, 1983.
Bruchey, Stuart. Enterprise: The Dynamic Economy of a Free People.
Cambridge, Mass.: Harvard University Press, 1990.
Flink, James. The Car Culture. Cambridge, Mass.: MIT Press, 1975.
Hayes, Robert. Restoring Our Competitive Edge. New York: Wiley, 1984.
Olson, Sidney. Young Henry Ford: A Picture History of the First Forty
Years. Detroit: Wayne State University Press, 1997.Wiley, 1984.

76
Atomic bomb
Atomic bomb
The invention: A weapon of mass destruction created during
World War II that utilized nuclear fission to create explosions
equivalent to thousands of tons of trinitrotoluene (TNT),
The people behind the invention:
J. Robert Oppenheimer (1904-1967), an American physicist
Leslie Richard Groves (1896-1970), an American engineer and
Army general
Enrico Fermi (1900-1954), an Italian American nuclear physicist
Niels Bohr (1885-1962), a Danish physicist
Energy on a Large Scale
The first evidence of uranium fission (the splitting of uranium
atoms) was observed by German chemists Otto Hahn and Fritz
Strassmann in Berlin at the end of 1938. When these scientists discovered
radioactive barium impurities in neutron-irradiated uranium,
they wrote to their colleague Lise Meitner in Sweden. She and
her nephew, physicist Otto Robert Frisch, calculated the large release
of energy that would be generated during the nuclear fission
of certain elements. This result was reported to Niels Bohr in Copenhagen.
Meanwhile, similar fission energies were measured by Frédéric
Joliot and his associates in Paris, who demonstrated the release of
up to three additional neutrons during nuclear fission. It was recognized
immediately that if neutron-induced fission released enough
additional neutrons to cause at least one more such fission, a selfsustaining
chain reaction would result, yielding energy on a large
scale.
While visiting the United States from January to May of 1939,
Bohr derived a theory of fission with John Wheeler of Princeton
University. This theory led Bohr to predict that the common isotope
uranium 238 (which constitutes 99.3 percent of naturally occurring
uranium) would require fast neutrons for fission, but that the rarer
uranium 235 would fission with neutrons of any energy. This meant

that uranium 235 would be far more suitable for use in any sort of
bomb. Uranium bombardment in a cyclotron led to the discovery of
plutonium in 1940 and the discovery that plutonium 239 was fissionable—and
thus potentially good bomb material. Uranium 238
was then used to “breed” (create) plutonium 239, which was then
separated from the uranium by chemical methods.
During 1942, the Manhattan District of the Army Corps of Engineers
was formed under General Leslie Richard Groves, an engineer
and Army general who contracted with E. I. Du Pont de
Nemours and Company to construct three secret atomic cities at a
total cost of $2 billion. At Oak Ridge, Tennessee, twenty-five thousand
workers built a 1,000-kilowatt reactor as a pilot plant. Asecond
city of sixty thousand inhabitants was built at Hanford, Washington,
where three huge reactors and remotely controlled plutoniumextraction
plants were completed in early 1945.
A Sustained and Awesome Roar
Atomic bomb / 77
Studies of fast-neutron reactions for an atomic bomb were brought
together in Chicago in June of 1942 under the leadership of J. Robert
Oppenheimer. He soon became a personal adviser to Groves, who
built for Oppenheimer a laboratory for the design and construction
of the bomb at Los Alamos, New Mexico. In 1943, Oppenheimer
gathered two hundred of the best scientists in what was by now being
called the Manhattan Project to live and work in this third secret
city.
Two bomb designs were developed. A gun-type bomb called
“Little Boy” used 15 kilograms of uranium 235 in a 4,500-kilogram
cylinder about 2 meters long and 0.5 meter in diameter, in which a
uranium bullet could be fired into three uranium target rings to
form a critical mass. An implosion-type bomb called “Fat Man” had
a 5-kilogram spherical core of plutonium about the size of an orange,
which could be squeezed inside a 2,300-kilogram sphere
about 1.5 meters in diameter by properly shaped explosives to make
the mass critical in the shorter time required for the faster plutonium
fission process.
A flat scrub region 200 kilometers southeast of Alamogordo,
called Trinity, was chosen for the test site, and observer bunkers

78 / Atomic bomb
were built about 10 kilometers from a 30-meter steel tower. On July
13, 1945, one of the plutonium bombs was assembled at the site; the
next morning, it was raised to the top of the tower. Two days later,
on July 16, after a short thunderstorm delay, the bomb was detonated
at 5:30 a.m. The resulting implosion initiated a chain reaction
of nearly 60 fission generations in about a microsecond. It produced
an intense flash of light and a fireball that expanded to a diameter of
about 600 meters in two seconds, rose to a height of more than 12 kilometers,
and formed an ominous mushroom shape. Forty seconds
later, an air blast hit the observer bunkers, followed by a sustained
and awesome roar. Measurements confirmed that the explosion had
the power of 18.6 kilotons of trinitrotoluene (TNT), nearly four
times the predicted value.
Impact
On March 9, 1945, 325 American B-29 bombers dropped 2,000
tons of incendiary bombs on Tokyo, resulting in 100,000 deaths from
the fire storms that swept the city. Nevertheless, the Japanese military
refused to surrender, and American military plans called for an
invasion of Japan, with estimates of up to a half million American
casualties, plus as many as 2 million Japanese casualties. On August
6, 1945, after authorization by President Harry S. Truman, the
B-29 Enola Gay dropped the uranium Little Boy bomb on Hiroshima
at 8:15 a.m. On August 9, the remaining plutonium Fat Man bomb
was dropped on Nagasaki. Approximately 100,000 people died at
Hiroshima (out of a population of 400,000), and about 50,000 more
died at Nagasaki. Japan offered to surrender on August 10, and after
a brief attempt by some army officers to rebel, an official announcement
by Emperor Hirohito was broadcast on August 15.
The development of the thermonuclear fusion bomb, in which
hydrogen isotopes could be fused together by the force of a fission
explosion to produce helium nuclei and almost unlimited energy,
had been proposed early in the Manhattan Project by physicist Edward
Teller. Little effort was invested in the hydrogen bomb until
after the surprise explosion of a Soviet atomic bomb in September,
1949, which had been built with information stolen from the Manhattan
Project. After three years of development under Teller’s

guidance, the first successful H-bomb was exploded on November
1, 1952, obliterating the Elugelab atoll in the Marshall Islands of
the South Pacific. The arms race then accelerated until each side had
stockpiles of thousands of H-bombs.
The Manhattan Project opened a Pandora’s box of nuclear weapons
that would plague succeeding generations, but it contributed
more than merely weapons. About 19 percent of the electrical energy
in the United States is generated by about 110 nuclear reactors
producing more than 100,000 megawatts of power. More than 400
reactors in thirty countries provide 300,000 megawatts of the world’s
power. Reactors have made possible the widespread use of radioisotopes
in medical diagnosis and therapy. Many of the techniques
for producing and using these isotopes were developed by the hundreds
of nuclear physicists who switched to the field of radiation
biophysics after the war, ensuring that the benefits of their wartime
efforts would reach the public.
See also Airplane; Breeder reactor; Cruise missile; Hydrogen
bomb; Rocket; Stealth aircraft; V-2 rocket.
Further Reading
Atomic bomb / 79
Goudsmit, Samuel Abraham, and Albert E. Moyer. The History of
Modern Physics, 1800-1950. Los Angeles: Tomash Publishers, 1983.
Henshall, Phillip. The Nuclear Axis: Germany, Japan, and the Atom
Bomb Race, 1939-1945. Stoud: Sutton, 2000.
Krieger, David. Splitting the Atom: A Chronology of the Nuclear Age.
Santa Barbara, Calif.: Nuclear Age Peace Foundation, 1998.
Smith, June. How the Atom Bombs Began, 1939-1946. London: Brockwell,
1988.

80
Atomic clock
Atomic clock
The invention: A clock using the ammonia molecule as its oscillator
that surpasses mechanical clocks in long-term stability, precision,
and accuracy.
The person behind the invention:
Harold Lyons (1913-1984), an American physicist
Time Measurement
The accurate measurement of basic quantities, such as length,
electrical charge, and temperature, is the foundation of science. The
results of such measurements dictate whether a scientific theory is
valid or must be modified or even rejected. Many experimental
quantities change over time, but time cannot be measured directly.
It must be measured by the occurrence of an oscillation or rotation,
such as the twenty-four-hour rotation of the earth. For centuries, the
rising of the Sun was sufficient as a timekeeper, but the need for
more precision and accuracy increased as human knowledge grew.
Progress in science can be measured by how accurately time has
been measured at any given point. In 1713, the British government,
after the disastrous sinking of a British fleet in 1707 because of a miscalculation
of longitude, offered a reward of 20,000 pounds for the
invention of a ship’s chronometer (a very accurate clock). Latitude
is determined by the altitude of the Sun above the southern horizon
at noon local time, but the determination of longitude requires an
accurate clock set at Greenwich, England, time. The difference between
the ship’s clock and the local sun time gives the ship’s longitude.
This permits the accurate charting of new lands, such as those
that were being explored in the eighteenth century. John Harrison,
an English instrument maker, eventually built a chronometer that
was accurate within one minute after five months at sea. He received
his reward from Parliament in 1765.
Atomic Clocks Provide Greater Stability
A clock contains four parts: energy to keep the clock operating,
an oscillator, an oscillation counter, and a display. A grandfather

Atomic clock / 81
clock has weights that fall slowly, providing energy that powers the
clock’s gears. The pendulum, a weight on the end of a rod, swings
back and forth (oscillates) with a regular beat. The length of the rod
determines the pendulum’s period of oscillation. The pendulum is
attached to gears that count the oscillations and drive the display
hands.
There are limits to a mechanical clock’s accuracy and stability.
The length of the rod changes as the temperature changes, so the
period of oscillation changes. Friction in the gears changes as they
wear out. Making the clock smaller increases its accuracy, precision,
and stability. Accuracy is how close the clock is to telling the actual
time. Stability indicates how the accuracy changes over time, while
precision is the number of accurate decimal places in the display. A
grandfather clock, for example, might be accurate to ten seconds per
day and precise to a second, while having a stability of minutes per
week.
Applying an electrical signal to a quartz crystal will make the
crystal oscillate at its natural vibration frequency, which depends on
its size, its shape, and the way in which it was cut from the larger
crystal. Since the faster a clock’s oscillator vibrates, the more precise
the clock, a crystal-based clock is more precise than a large pendulum
clock. By keeping the crystal under constant temperature, the
clock is kept accurate, but it eventually loses its stability and slowly
wears out.
In 1948, Harold Lyons and his colleagues at the National Bureau
of Standards (NBS) constructed the first atomic clock, which used
the ammonia molecule as its oscillator. Such a clock is called an
atomic clock because, when it operates, a nitrogen atom vibrates.
The pyramid-shaped ammonia molecule is composed of a triangular
base; there is a hydrogen atom at each corner and a nitrogen
atom at the top of the pyramid. The nitrogen atom does not remain
at the top; if it absorbs radio waves of the right energy and frequency,
it passes through the base to produce an upside-down pyramid
and then moves back to the top. This oscillation frequency occurs
at 23,870 megacycles (1 megacycle equals 1 million cycles) per
second.
Lyons’s clock was actually a quartz-ammonia clock, since the signal
from a quartz crystal produced radio waves of the crystal’s fre-

82 / Atomic clock
quency that were fed into an ammonia-filled tube. If the radio
waves were at 23,870 megacycles, the ammonia molecules absorbed
the waves; a detector sensed this, and it sent no correction signal to
the crystal. If radio waves deviated from 23,870 megacycles, the ammonia
did not absorb them, the detector sensed the unabsorbed radio
waves, and a correction signal was sent to the crystal. The
atomic clock’s accuracy and precision were comparable to those of a
quartz-based clock—one part in a hundred million—but the atomic
clock was more stable because molecules do not wear out.
The atomic clock’s accuracy was improved by using cesium
133 atoms as the source of oscillation. These atoms oscillate at
9,192,631,770 plus or minus 20 cycles per second. They are accurate
to a billionth of a second per day and precise to nine decimal places.
A cesium clock is stable for years. Future developments in atomic
clocks may see accuracies of one part in a million billions.
Impact
The development of stable, very accurate atomic clocks has farreaching
implications for many areas of science. Global positioning
satellites send signals to receivers on ships and airplanes. By timing
the signals, the receiver’s position is calculated to within several
meters of its true location.
Chemists are interested in finding the speed of chemical reactions,
and atomic clocks are used for this purpose. The atomic clock
led to the development of the maser (an acronym for microwave amplification
by stimulated emission of radiation), which is used to
amplify weak radio signals, and the maser led to the development
of the laser, a light-frequency maser that has more uses than can be
listed here.
Atomic clocks have been used to test Einstein’s theories of relativity
that state that time on a moving clock, as observed by a stationary
observer, slows down, and that a clock slows down near a
large mass (because of the effects of gravity). Under normal conditions
of low velocities and low mass, the changes in time are very
small, but atomic clocks are accurate and stable enough to detect
even these small changes. In such experiments, three sets of clocks
were used—one group remained on Earth, one was flown west

around the earth on a jet, and the last set was flown east. By comparing
the times of the in-flight sets with the stationary set, the
predicted slowdowns of time were observed and the theories were
verified.
See also Carbon dating; Cyclotron; Electric clock; Laser; Synchrocyclotron;
Tevatron accelerator.
Further Reading
Atomic clock / 83
Audoin, Claude, and Bernard Guinot. The Measurement of Time:
Time, Frequency, and the Atomic Clock. New York: Cambridge University
Press, 2001.
Barnett, Jo Ellen. Time’s Pendulum: The Quest to Capture Time—From
Sundials to Atomic Clocks. New York: Plenum Trade, 1998.
Bendick, Jeanne. The First Book of Time. New York: F. Watts, 1970.
“Ultra-Accurate Atomic Clock Unveiled at NIST Laboratory.” Research
and Development 42, no. 2 (February, 2000).

84
Atomic-powered ship
Atomic-powered ship
The invention: The world’s first atomic-powered merchant ship
demonstrated a peaceful use of atomic power.
The people behind the invention:
Otto Hahn (1879-1968), a German chemist
Enrico Fermi (1901-1954), an Italian American physicist
Dwight D. Eisenhower (1890-1969), president of the United
States, 1953-1961
Splitting the Atom
In 1938, Otto Hahn, working at the Kaiser Wilhelm Institute for
Chemistry, discovered that bombarding uranium atoms with neutrons
causes them to split into two smaller, lighter atoms. A large
amount of energy is released during this process, which is called
“fission.” When one kilogram of uranium is fissioned, it releases the
same amount of energy as does the burning of 3,000 metric tons of
coal. The fission process also releases new neutrons.
Enrico Fermi suggested that these new neutrons could be used to
split more uranium atoms and produce a chain reaction. Fermi and
his assistants produced the first human-made chain reaction at the
University of Chicago on December 2, 1942. Although the first use
of this new energy source was the atomic bombs that were used to
defeat Japan in World War II, it was later realized that a carefully
controlled chain reaction could produce useful energy. The submarine
Nautilus, launched in 1954, used the energy released from fission
to make steam to drive its turbines.
U.S. President Dwight David Eisenhower proposed his “Atoms
for Peace” program in December, 1953. On April 25, 1955, President
Eisenhower announced that the “Atoms for Peace” program would
be expanded to include the design and construction of an atomicpowered
merchant ship, and he signed the legislation authorizing
the construction of the ship in 1956.

Savannah’s Design and Construction
Atomic-powered ship / 85
A contract to design an atomic-powered merchant ship was
awarded to George G. Sharp, Inc., on April 4, 1957. The ship was to
carry approximately one hundred passengers (later reduced to sixty
to reduce the ship’s cost) and 10,886 metric tons of cargo while making
a speed of 21 knots, about 39 kilometers per hour. The ship was
to be 181 meters long and 23.7 meters wide. The reactor was to provide
steam for a 20,000-horsepower turbine that would drive the
ship’s propeller. Most of the ship’s machinery was similar to that of
existing ships; the major difference was that steam came from a reactor
instead of a coal- or oil-burning boiler.
New York Shipbuilding Corporation of Camden, New Jersey,
won the contract to build the ship on November 16, 1957. States Marine
Lines was selected in July, 1958, to operate the ship. It was christened
Savannah and launched on July 21, 1959. The name Savannah
was chosen to honor the first ship to use steam power while crossing
an ocean. This earlier Savannah was launched in New York City
in 1818.
Ships are normally launched long before their construction is
complete, and the new Savannah was no exception. It was finally
turned over to States Marine Lines on May 1, 1962. After extensive
testing by its operators and delays caused by labor union disputes,
it began its maiden voyage from Yorktown, Virginia, to Savannah,
Georgia, on August 20, 1962. The original budget for design and
construction was $35 million, but by this time, the actual cost was
about $80 million.
Savannah‘s nuclear reactor was fueled with about 7,000 kilograms
(15,400 pounds) of uranium. Uranium consists of two forms,
or “isotopes.” These are uranium 235, which can fission, and uranium
238, which cannot. Naturally occurring uranium is less than 1
percent uranium 235, but the uranium in Savannah‘s reactor had
been enriched to contain nearly 5 percent of this isotope. Thus, there
was less than 362 kilograms of usable uranium in the reactor. The
ship was able to travel about 800,000 kilometers on this initial fuel
load. Three and a half million kilograms of water per hour flowed
through the reactor under a pressure of 5,413 kilograms per square
centimeter. It entered the reactor at 298.8 degrees Celsius and left at

86 / Atomic-powered ship
317.7 degrees Celsius. Water leaving the reactor passed through a
heat exchanger called a “steam generator.” In the steam generator,
reactor water flowed through many small tubes. Heat passed through
the walls of these tubes and boiled water outside them. About
113,000 kilograms of steam per hour were produced in this way at a
pressure of 1,434 kilograms per square centimeter and a temperature
of 240.5 degrees Celsius.
Labor union disputes dogged Savannah‘s early operations, and it
did not start its first trans-Atlantic crossing until June 8, 1964. Savannah
was never a money maker. Even in the 1960’s, the trend was toward
much bigger ships. It was announced that the ship would be
retired in August, 1967, but that did not happen. It was finally put
out of service in 1971. Later, Savannah was placed on permanent display
at Charleston, South Carolina.
Consequences
Following the United States’ lead, Germany and Japan built
atomic-powered merchant ships. The Soviet Union is believed to
have built several atomic-powered icebreakers. Germany’s Otto
Hahn, named for the scientist who first split the atom, began service
in 1968, and Japan’s Mutsuai was under construction as Savannah retired.
Numerous studies conducted in the early 1970’s claimed to prove
that large atomic-powered merchant ships were more profitable
than oil-fired ships of the same size. Several conferences devoted to
this subject were held, but no new ships were built.
Although the U.S. Navy has continued to use reactors to power
submarines, aircraft carriers, and cruisers, atomic power has not
been widely used for merchant-ship propulsion. Labor union problems
such as those that haunted Savannah, high insurance costs, and
high construction costs are probably the reasons. Public opinion, after
the reactor accidents at Three Mile Island (in 1979) and Chernobyl
(in 1986) is also a factor.
See also Gyrocompass; Hovercraft; Nuclear reactor; Supersonic
passenger plane.

Further Reading
Atomic-powered ship / 87
Epstein, Sam Epstein, Beryl (William) Epstein, and Raymond
Burns. Enrico Fermi, Father of Atomic Power. Champaign, Ill. Garrard
Publishing, 1970.
Hahn, Otto, and Wily Ley. Otto Hahn: A Scientific Autobiography.
New York: C. Scribner’s Sons, 1966.
Hoffman, Klaus. Otto Hahn: Achievement and Responsibility. New
York: Springer, 2001.
“The Race to Power Bigger, Faster Ships.” Business Week 2305 (November
10, 1973).
“Underway on Nuclear Power.” All Hands 979 (November, 1998).

88
Autochrome plate
Autochrome plate
The invention: The first commercially successful process in which
a single exposure in a regular camera produced a color image.
The people behind the invention:
Louis Lumière (1864-1948), a French inventor and scientist
Auguste Lumière (1862-1954), an inventor, physician, physicist,
chemist, and botanist
Alphonse Seyewetz, a skilled scientist and assistant of the
Lumière brothers
Adding Color
In 1882, Antoine Lumière, painter, pioneer photographer, and father
of Auguste and Louis, founded a factory to manufacture photographic
gelatin dry-plates. After the Lumière brothers took over the
factory’s management, they expanded production to include roll
film and printing papers in 1887 and also carried out joint research
that led to fundamental discoveries and improvements in photographic
development and other aspects of photographic chemistry.
While recording and reproducing the actual colors of a subject
was not possible at the time of photography’s inception (about
1822), the first practical photographic process, the daguerreotype,
was able to render both striking detail and good tonal quality. Thus,
the desire to produce full-color images, or some approximation to
realistic color, occupied the minds of many photographers and inventors,
including Louis and Auguste Lumière, throughout the
nineteenth century.
As researchers set out to reproduce the colors of nature, the first
process that met with any practical success was based on the additive
color theory expounded by the Scottish physicist James Clerk
Maxwell in 1861. He believed that any color can be created by
adding together red, green, and blue light in certain proportions.
Maxwell, in his experiments, had taken three negatives through
screens or filters of these additive primary colors. He then took
slides made from these negatives and projected the slides through

Antoine Lumière and Sons
Autochrome plate / 89
Antoine Lumière was explosive in temperament, loved a
good fight, and despised Americans. With these qualities—and
his sons to take care of the practicalities—he turned France into
a leader of the early photography and film industries.
Lumière was born into a family of wine growers in 1840 and
trained to be a sign painter. Bored with his job, he learned the
new art of photography, set up a studio in Lyon, and began to
experiment with ways to make his own photographic plates.
Failures led to frustration, and frustration ignited his temper,
which often ended in his smashing the furniture and glassware
nearby. His sons, Auguste, born 1862, and Louis, born 1864,
came to the rescue. Louis, a science whiz as a teenager, succeeded
where his father had failed. The dry plate he invented,
Blue Label, was the most sensitive yet. The Lumières set up a
factory to manufacture the plates and quickly found themselves
wealthy, but the old man’s love of extravagant spending
and parties led them to the door of bankruptcy in 1882. His sons
had to take control to save the family finances.
The father, an ardent French patriot, soon threw himself into
a new crusade. American tariffs made it impossible for the
Lumières to make a profit selling their photographic plates in
the United States, which so angered the old man that he
looked for revenge. He found it in the form of Thomas Edison’s
Kinetoscope in 1894. He got hold of samples, and soon
the family factory was making motion picture film of its own
and could undersell Edison in France. Louis also invented a
projector, adapted from a sewing machine, that made it possible
for movies to be shown to audiences.
Before Antoine Lumière died in Paris in 1911, he had the satisfaction
of seeing his beloved France producing better, cheaper
photographic products than those available from America, as
well as becoming a pioneer in film making.
the same filters onto a screen so that their images were superimposed.
As a result, he found that it was possible to reproduce the exact
colors as well as the form of an object.
Unfortunately, since colors could not be printed in their tonal
relationships on paper before the end of the nineteenth century,

90 / Autochrome plate
Maxwell’s experiment was unsuccessful. Although Frederick E.
Ives of Philadelphia, in 1892, optically united three transparencies
so that they could be viewed in proper alignment by looking through
a peephole, viewing the transparencies was still not as simple as
looking at a black-and-white photograph.
The Autochrome Plate
The first practical method of making a single photograph that
could be viewed without any apparatus was devised by John Joly of
Dublin in 1893. Instead of taking three separate pictures through
three colored filters, he took one negative through one filter minutely
checkered with microscopic areas colored red, green, and
blue. The filter and the plate were exactly the same size and were
placed in contact with each other in the camera. After the plate was
developed, a transparency was made, and the filter was permanently
attached to it. The black-and-white areas of the picture allowed
more or less light to shine through the filters; if viewed from a
proper distance, the colored lights blended to form the various colors
of nature.
In sum, the potential principles of additive color and other methods
and their potential applications in photography had been discovered
and even experimentally demonstrated by 1880. Yet a practical
process of color photography utilizing these principles could
not be produced until a truly panchromatic emulsion was available,
since making a color print required being able to record the primary
colors of the light cast by the subject.
Louis and Auguste Lumière, along with their research associate
Alphonse Seyewetz, succeeded in creating a single-plate process
based on this method in 1903. It was introduced commercially as the
autochrome plate in 1907 and was soon in use throughout the
world. This process is one of many that take advantage of the limited
resolving power of the eye. Grains or dots too small to be recognized
as separate units are accepted in their entirety and, to the
sense of vision, appear as tones and continuous color.

Impact
While the autochrome plate remained one of the most popular
color processes until the 1930’s, soon this process was superseded by
subtractive color processes. Leopold Mannes and Leopold Godowsky,
both musicians and amateur photographic researchers who eventually
joined forces with Eastman Kodak research scientists, did the
most to perfect the Lumière brothers’ advances in making color
photography practical. Their collaboration led to the introduction in
1935 of Kodachrome, a subtractive process in which a single sheet of
film is coated with three layers of emulsion, each sensitive to one
primary color. A single exposure produces a color image.
Color photography is now commonplace. The amateur market is
enormous, and the snapshot is almost always taken in color. Commercial
and publishing markets use color extensively. Even photography
as an art form, which was done in black and white through
most of its history, has turned increasingly to color.
See also Color film; Instant photography; Xerography.
Further Reading
Autochrome plate / 91
Collins, Douglas. The Story of Kodak. New York: Harry N. Abrams,
1990.
Glendinning, Peter. Color Photography: History, Theory, and Darkroom
Technique. Englewood Cliffs, N.J.: Prentice-Hall, 1985.
Lartigue, Jacques-Henri, and Georges Herscher. The Autochromes of
J. H. Lartigue, 1912-1927. New York: Viking Press, 1981.
Tolstoy, Ivan. James Clerk Maxwell: A Biography. Chicago: University
of Chicago Press, 1982.
Wood, John. The Art of the Autochrome: The Birth of Color Photography.
Iowa City: University of Iowa Press, 1993.

92
BASIC programming language
BASIC programming language
The invention: An interactive computer system and simple programming
language that made it easier for nontechnical people
to use computers.
The people behind the invention:
John G. Kemeny (1926-1992), the chairman of Dartmouth’s
mathematics department
Thomas E. Kurtz (1928- ), the director of the Kiewit
Computation Center at Dartmouth
Bill Gates (1955- ), a cofounder and later chairman of the
board and chief operating officer of the Microsoft
Corporation
The Evolution of Programming
The first digital computers were developed during World War II
(1939-1945) to speed the complex calculations required for ballistics,
cryptography, and other military applications. Computer technology
developed rapidly, and the 1950’s and 1960’s saw computer systems
installed throughout the world. These systems were very large
and expensive, requiring many highly trained people for their operation.
The calculations performed by the first computers were determined
solely by their electrical circuits. In the 1940’s, The American
mathematician John von Neumann and others pioneered the idea of
computers storing their instructions in a program, so that changes
in calculations could be made without rewiring their circuits. The
programs were written in machine language, long lists of zeros and
ones corresponding to on and off conditions of circuits. During the
1950’s, “assemblers” were introduced that used short names for
common sequences of instructions and were, in turn, transformed
into the zeros and ones intelligible to the computer. The late 1950’s
saw the introduction of high-level languages, notably Formula Translation
(FORTRAN), Common Business Oriented Language (COBOL),
and Algorithmic Language (ALGOL), which used English words to

communicate instructions to the computer. Unfortunately, these
high-level languages were complicated; they required some knowledge
of the computer equipment and were designed to be used by
scientists, engineers, and other technical experts.
Developing BASIC
BASIC programming language / 93
John G. Kemeny was chairman of the department of mathematics
at Dartmouth College in Hanover, New Hampshire. In 1962,
Thomas E. Kurtz, Dartmouth’s computing director, approached
Kemeny with the idea of implementing a computer system at Dartmouth
College. Both men were dedicated to the idea that liberal arts
students should be able to make use of computers. Although the English
commands of FORTRAN and ALGOL were a tremendous improvement
over the cryptic instructions of assembly language, they
were both too complicated for beginners. Kemeny convinced Kurtz
that they needed a completely new language, simple enough for beginners
to learn quickly, yet flexible enough for many different
kinds of applications.
The language they developed was known as the “Beginner’s Allpurpose
Symbolic Instruction Code,” or BASIC. The original language
consisted of fourteen different statements. Each line of a
BASIC program was preceded by a number. Line numbers were referenced
by control flow statements, such as, “IFX=9THEN GOTO
200.” Line numbers were also used as an editing reference. If line 30
of a program contained an error, the programmer could make the
necessary correction merely by retyping line 30.
Programming in BASIC was first taught at Dartmouth in the fall
of 1964. Students were ready to begin writing programs after two
hours of classroom lectures. By June of 1968, more than 80 percent of
the undergraduates at Dartmouth could write a BASIC program.
Most of them were not science majors and used their programs in
conjunction with other nontechnical courses.
Kemeny and Kurtz, and later others under their supervision,
wrote more powerful versions of BASIC that included support for
graphics on video terminals and structured programming. The creators
of BASIC, however, always tried to maintain their original design
goal of keeping BASIC simple enough for beginners.

94 / BASIC programming language
Consequences
Kemeny and Kurtz encouraged the widespread adoption of BA-
SIC by allowing other institutions to use their computer system and
by placing BASIC in the public domain. Over time, they shaped BA-
SIC into a powerful language with numerous features added in response
to the needs of its users. What Kemeny and Kurtz had not
foreseen was the advent of the microprocessor chip in the early
1970’s, which revolutionized computer technology. By 1975, microcomputer
kits were being sold to hobbyists for well under a thousand
dollars. The earliest of these was the Altair.
That same year, prelaw student William H. Gates (1955- ) was
persuaded by a friend, Paul Allen, to drop out of Harvard University
and help create a version of BASIC that would run on the Altair.
Gates and Allen formed a company, Microsoft Corporation, to sell
their BASIC interpreter, which was designed to fit into the tiny
memory of the Altair. It was about as simple as the original Dartmouth
BASIC but had to depend heavily on the computer hardware.
Most computers purchased for home use still include a version
of Microsoft Corporation’s BASIC.
See also BINAC computer; COBOL computer language; FOR-
TRAN programming language; SAINT; Supercomputer.
Further Reading
Kemeney, John G., and Thomas E. Kurtz. True BASIC: The Structured
Language System for the Future. Reference Manual. West Lebanon,
N.H.: True BASIC, 1988.
Kurtz, Thomas E., and John G. Kemeney. BASIC. 5th ed. Hanover,
N.H., 1970.
Spencer, Donald D. Great Men and Women of Computing. 2d ed. Ormond
Beach, Fla.: Camelot Publishing, 1999.

Bathyscaphe
Bathyscaphe
The invention: A submersible vessel capable of exploring the
deepest trenches of the world’s oceans.
The people behind the invention:
William Beebe (1877-1962), an American biologist and explorer
Auguste Piccard (1884-1962), a Swiss-born Belgian physicist
Jacques Piccard (1922- ), a Swiss ocean engineer
Early Exploration of the Deep Sea
The first human penetration of the deep ocean was made by William
Beebe in 1934, when he descended 923 meters into the Atlantic
Ocean near Bermuda. His diving chamber was a 1.5-meter steel ball
that he named Bathysphere, from the Greek word bathys (deep) and
the word sphere, for its shape. He found that a sphere resists pressure
in all directions equally and is not easily crushed if it is constructed
of thick steel. The bathysphere weighed 2.5 metric tons. It
had no buoyancy and was lowered from a surface ship on a single
2.2-centimeter cable; a broken cable would have meant certain
death for the bathysphere’s passengers.
Numerous deep dives by Beebe and his engineer colleague, Otis
Barton, were the first uses of submersibles for science. Through two
small viewing ports, they were able to observe and photograph
many deep-sea creatures in their natural habitats for the first time.
They also made valuable observations on the behavior of light as
the submersible descended, noting that the green surface water became
pale blue at 100 meters, dark blue at 200 meters, and nearly
black at 300 meters. A technique called “contour diving” was particularly
dangerous. In this practice, the bathysphere was slowly
towed close to the seafloor. On one such dive, the bathysphere narrowly
missed crashing into a coral crag, but the explorers learned a
great deal about the submarine geology of Bermuda and the biology
of a coral-reef community. Beebe wrote several popular and scientific
books about his adventures that did much to arouse interest in
the ocean.
95

96 / Bathyscaphe
Testing the Bathyscaphe
The next important phase in the exploration of the deep ocean
was led by the Swiss physicist Auguste Piccard. In 1948, he launched
a new type of deep-sea research craft that did not require a cable and
that could return to the surface by means of its own buoyancy. He
called the craft a bathyscaphe, which is Greek for “deep boat.”
Piccard began work on the bathyscaphe in 1937, supported by a
grant from the Belgian National Scientific Research Fund. The German
occupation of Belgium early in World War II cut the project
short, but Piccard continued his work after the war. The finished
bathyscaphe was named FNRS 2, for the initials of the Belgian fund
that had sponsored the project. The vessel was ready for testing in
the fall of 1948.
The first bathyscaphe, as well as later versions, consisted of
two basic components: first, a heavy steel cabin to accommodate
observers, which looked somewhat like an enlarged version of
Beebe’s bathysphere; and second, a light container called a float,
filled with gasoline, that provided lifting power because it was
lighter than water. Enough iron shot was stored in silos to cause
the vessel to descend. When this ballast was released, the gasoline
in the float gave the bathyscaphe sufficient buoyancy to return to
the surface.
Piccard’s bathyscaphe had a number of ingenious devices. Jacques-
Yves Cousteau, inventor of the Aqualung six years earlier, contributed
a mechanical claw that was used to take samples of rocks, sediment,
and bottom creatures. A seven-barreled harpoon gun, operated
by water pressure, was attached to the sphere to capture
specimens of giant squids or other large marine animals for study.
The harpoons had electrical-shock heads to stun the “sea monsters,”
and if that did not work, the harpoon could give a lethal injection of
strychnine poison. Inside the sphere were various instruments for
measuring the deep-sea environment, including a Geiger counter
for monitoring cosmic rays. The air-purification system could support
two people for up to twenty-four hours. The bathyscaphe had a
radar mast to broadcast its location as soon as it surfaced. This was
essential because there was no way for the crew to open the sphere
from the inside.

Auguste Piccard
Bathyscaphe / 97
Auguste Piccard used balloons to set records in altitude both
above sea level and below sea level. However, setting records
was not his purpose: He went where no one had gone before for
the sake of science.
Born in Basel, Switzerland, in 1884, Auguste and
his twin brother, Jean-Félix Piccard, studied in Zurich.
After university in 1913, Auguste, a physicist,
and Jean-Félix, a chemist, took up hot-air ballooning,
and they joined the balloon section of the Swiss Army
in 1915.
Auguste moved to Brussels, Belgium, in 1922 to
take a professorship of applied physics, and there he
continued his ballooning. His subject of interest was
cosmic rays, and in order to study them he had to get above the
thick lower layer of atmosphere. Accordingly, he designed hydrogen-filled
balloons that could reach high altitude. A ballshaped,
pressurized gondola carried him, his instruments, and
one colleague to 51,775 feet altitude in 1931 and to 53,152 feet in
1932. Both were records.
Auguste, working with his son Jacques, then turned his attention
to the sea. In order to explore the largely unknown world
underwater, he built the bathyscaphe. It was really just another
type of balloon, one which was made of steel and carried him
inside. His dives with his son in various models of bathyscaphe
set record after record. Their 1953 dive down 10,300 feet into the
Mediterranean Sea was the deepest until Jacques, accompanied
by a U.S. Navy officer, descended to the deepest spot on Earth
seven years later.
The FNRS 2 was first tested off the Cape Verde Islands with the
assistance of the French navy. Although Piccard descended to only
25 meters, the dive demonstrated the potential of the bathyscaphe.
On the second dive, the vessel was severely damaged by waves, and
further tests were suspended. A redesigned and rebuilt bathyscaphe,
renamed FNRS 3 and operated by the French navy, descended to a
depth of 4,049 meters off Dakar, Senegal, on the west coast of Africa
in early 1954.
In August, 1953, Auguste Piccard, with his son Jacques, launched a
(Library of Congress)

98 / Bathyscaphe
greatly improved bathyscaphe, the Trieste, which they named for the
Italian city in which it was built. In September of the same year, the
Trieste successfully dived to 3,150 meters in the Mediterranean Sea. The
Piccards glimpsed, for the first time, animals living on the seafloor at
that depth. In 1958, the U.S. Navy purchased the Trieste and transported
it to California, where it was equipped with a new cabin designed
to enable the vessel to reach the seabed of the great oceanic
trenches. Several successful descents were made in the Pacific by
Jacques Piccard, and on January 23, 1960, Piccard, accompanied by
Lieutenant Donald Walsh of the U.S. Navy, dived a record 10,916 meters
to the bottom of the Mariana Trench near the island of Guam.
Impact
The oceans have always raised formidable barriers to humanity’s
curiosity and understanding. In 1960, two events demonstrated the
ability of humans to travel underwater for prolonged periods and to
observe the extreme depths of the ocean. The nuclear submarine
Triton circumnavigated the world while submerged, and Jacques
Piccard and Lieutenant Donald Walsh descended nearly 11 kilometers
to the bottom of the ocean’s greatest depression aboard the
Trieste. After sinking for four hours and forty-eight minutes, the
Trieste landed in the Challenger Deep of the Mariana Trench, the
deepest known spot on the ocean floor. The explorers remained on
the bottom for only twenty minutes, but they answered one of the
biggest questions about the sea: Can animals live in the immense
cold and pressure of the deep trenches? Observations of red shrimp
and flatfishes proved that the answer was yes.
The Trieste played another important role in undersea exploration
when, in 1963, it located and photographed the wreckage of the
nuclear submarine Thresher. The Thresher had mysteriously disappeared
on a test dive off the New England coast, and the Navy had
been unable to find a trace of the lost submarine using surface vessels
equipped with sonar and remote-control cameras on cables.
Only the Trieste could actually search the bottom. On its third dive,
the bathyscaphe found a piece of the wreckage, and it eventually
photographed a 3,000-meter trail of debris that led to Thresher‘s hull,
at a depth of 2.5 kilometers.

These exploits showed clearly that scientific submersibles could
be used anywhere in the ocean. Piccard’s work thus opened the last
geographic frontier on Earth.
See also Aqualung; Bathysphere; Sonar; Ultrasound.
Further Reading
Bathyscaphe / 99
Ballard, Robert D., and Will Hively. The Eternal Darkness: A Personal
History of Deep-Sea Exploration. Princeton, N.J.: Princeton University
Press, 2000.
Piccard, Jacques, and Robert S. Dietz. Seven Miles Down: The Story of
the Bathyscaphe Trieste. New York: Longmans, 1962.
Welker, Robert Henry. Natural Man: The Life of William Beebe. Bloomington:
Indiana University Press, 1975.

100
Bathysphere
Bathysphere
The invention: The first successful chamber for manned deep-sea
diving missions.
The people behind the invention:
William Beebe (1877-1962), an American naturalist and curator
of ornithology
Otis Barton (1899- ), an American engineer
John Tee-Van (1897-1967), an American general associate with
the New York Zoological Society
Gloria Hollister Anable (1903?-1988), an American research
associate with the New York Zoological Society
Inner Space
Until the 1930’s, the vast depths of the oceans had remained
largely unexplored, although people did know something of the
ocean’s depths. Soundings and nettings of the ocean bottom had
been made many times by a number of expeditions since the 1870’s.
Diving helmets had allowed humans to descend more than 91 meters
below the surface, and the submarine allowed them to reach a
depth of nearly 120 meters. There was no firsthand knowledge,
however, of what it was like in the deepest reaches of the ocean: inner
space.
The person who gave the world the first account of life at great
depths was William Beebe. When he announced in 1926 that he was
attempting to build a craft to explore the ocean, he was already a
well-known naturalist. Although his only degrees had been honorary
doctorates, he was graduated as a special student in the Department
of Zoology of Columbia University in 1898. He began his lifelong
association with the New York Zoological Society in 1899.
It was during a trip to the Galápagos Islands off the west coast of
South America that Beebe turned his attention to oceanography. He
became the first scientist to use a diving helmet in fieldwork, swimming
in the shallow waters. He continued this shallow-water work
at the new station he established in 1928, with the permission of En-

glish authorities, on the tiny island of Nonesuch in the Bermudas.
Beebe realized, however, that he had reached the limits of the current
technology and that to study the animal life of the ocean depths
would require a new approach.
A New Approach
Bathysphere / 101
While he was considering various cylindrical designs for a new
deep-sea exploratory craft, Beebe was introduced to Otis Barton.
Barton, a young New Englander who had been trained as an engineer
at Harvard University, had turned to the problems of ocean
diving while doing postgraduate work at Columbia University. In
December, 1928, Barton brought his blueprints to Beebe. Beebe immediately
saw that Barton’s design was what he was looking for,
and the two went ahead with the construction of Barton’s craft.
The “bathysphere,” as Beebe named the device, weighed 2,268
kilograms and had a diameter of 1.45 meters and steel walls 3.8 centimeters
thick. The door, weighing 180 kilograms, would be fastened
over a manhole with ten bolts. Four windows, made of fused
quartz, were ordered from the General Electric Company at a cost of
$500 each. A 250-watt water spotlight lent by the Westinghouse
Company provided the exterior illumination, and a telephone lent
by the Bell Telephone Laboratory provided a means of communicating
with the surface. The breathing apparatus consisted of two oxygen
tanks that allowed 2 liters of oxygen per minute to escape into
the sphere. During the dive, the carbon dioxide and moisture were
removed, respectively, by trays containing soda lime and calcium
chloride. A winch would lower the bathysphere on a steel cable.
In early July, 1930, after several test dives, the first manned dive
commenced. Beebe and Barton descended to a depth of 244 meters.
A short circuit in one of the switches showered them with sparks
momentarily, but the descent was largely a success. Beebe and
Barton had descended farther than any human.
Two more days of diving yielded a final dive record of 435 meters
below sea level. Beebe and the other members of his staff (ichthyologist
John Tee-Van and zoologist Gloria Hollister Anable) saw many
species of fish and other marine life that previously had been seen
only after being caught in nets. These first dives proved that an un-

102 / Bathysphere
dersea exploratory craft had potential value, at least for deep water.
After 1932, the bathysphere went on display at the Century of Progress
Exhibition in Chicago.
In late 1933, the National Geographic Society offered to sponsor
another series of dives. Although a new record was not a stipulation,
Beebe was determined to supply one. The bathysphere was
completely refitted before the new dives.
An unmanned test dive to 920 meters was made on August 7,
1934, once again off Nonesuch Island. Minor adjustments were
made, and on the morning of August 11, the first dive commenced,
attaining a depth of 765 meters and recording a number of new scientific
observations. Several days later, on August 15, the weather
was again right for the dive.
This dive also paid rich dividends in the number of species of
deep-sea life observed. Finally, with only a few turns of cable left on
the winch spool, the bathysphere reached a record depth of 923 meters—almost
a kilometer below the ocean’s surface.
Impact
Barton continued to work on the bathysphere design for some
years. It was not until 1948, however, that his new design, the
benthoscope, was finally constructed. It was similar in basic design
to the bathysphere, though the walls were increased to withstand
greater pressures. Other improvements were made, but the essential
strengths and weaknesses remained. On August 16, 1949, Barton,
diving alone, broke the record he and Beebe had set earlier,
reaching a depth of 1,372 meters off the coast of Southern California.
The bathysphere effectively marked the end of the tethered exploration
of the deep, but it pointed the way to other possibilities.
The first advance in this area came in 1943, when undersea explorer
Jacques-Yves Cousteau and engineer Émile Gagnan developed the
Aqualung underwater breathing apparatus, which made possible
unfettered and largely unencumbered exploration down to about
60 meters. This was by no means deep diving, but it was clearly a
step along the lines that Beebe had envisioned for underwater research.
A further step came in the development of the bathyscaphe by

Auguste Piccard, the renowned Swiss physicist, who, in the 1930’s,
had conquered the stratosphere in high-altitude balloons. The bathyscaphe
was a balloon that operated in reverse. A spherical steel passenger
cabin was attached beneath a large float filled with gasoline
for buoyancy. Several tons of iron pellets held by electromagnets
acted as ballast. The bathyscaphe would sink slowly to the bottom
of the ocean, and when its passengers wished to return, the ballast
would be dumped. The craft would then slowly rise to the surface.
On September 30, 1953, Piccard touched bottom off the coast of Italy,
some 3,000 meters below sea level.
See also Aqualung; Bathyscaphe; Sonar; Ultrasound.
Further Reading
Bathysphere / 103
Ballard, Robert D., and Will Hively. The Eternal Darkness: A Personal
History of Deep-Sea Exploration. Princeton, N.J.: Princeton University
Press, 2000.
Forman, Will. The History of American Deep Submersible Operations,
1775-1995. Flagstaff, Ariz.: Best, 1999.
Welker, Robert Henry. Natural Man: The Life of William Beebe. Bloomington:
Indiana University Press, 1975.

104
BINAC computer
BINAC computer
The invention: The world’s first electronic general-purpose digital
computer.
The people behind the invention:
John Presper Eckert (1919-1995), an American electrical engineer
John W. Mauchly (1907-1980), an American physicist
John von Neumann (1903-1957), a Hungarian American
mathematician
Alan Mathison Turing (1912-1954), an English mathematician
Computer Evolution
In the 1820’s, there was a need for error-free mathematical and
astronomical tables for use in navigation, unreliable versions of
which were being produced by human “computers.” The problem
moved English mathematician and inventor Charles Babbage to design
and partially construct some of the earliest prototypes of modern
computers, with substantial but inadequate funding from the
British government. In the 1880’s, the search by the U.S. Bureau of
the Census for a more efficient method of compiling the 1890 census
led American inventor Herman Hollerith to devise a punched-card
calculator, a machine that reduced by several years the time required
to process the data.
The emergence of modern electronic computers began during
World War II (1939-1945), when there was an urgent need in the
American military for reliable and quickly produced mathematical
tables that could be used to aim various types of artillery. The calculation
of very complex tables had progressed somewhat since
Babbage’s day, and the human computers were being assisted by
mechanical calculators. Still, the growing demand for increased accuracy
and efficiency was pushing the limits of these machines.
Finally, in 1946, following three years of intense work at the University
of Pennsylvania’s Moore School of Engineering, John Presper
Eckert and John W. Mauchly presented their solution to the problems
in the form of the Electronic Numerical Integrator and Calcula-

tor (ENIAC) the world’s first electronic general-purpose digital
computer.
The ENIAC, built under a contract with the Army’s Ballistic Research
Laboratory, became a great success for Eckert and Mauchly,
but even before it was completed, they were setting their sights on
loftier targets. The primary drawback of the ENIAC was the great
difficulty involved in programming it. Whenever the operators
needed to instruct the machine to shift from one type of calculation
to another, they had to reset a vast array of dials and switches, unplug
and replug numerous cables, and make various other adjustments
to the multiple pieces of hardware involved. Such a mode of
operation was deemed acceptable for the ENIAC because, in computing
firing tables, it would need reprogramming only occasionally.
Yet if instructions could be stored in a machine’s memory, along
with the data, such a machine would be able to handle a wide range
of calculations with ease and efficiency.
The Turing Concept
BINAC computer / 105
The idea of a stored-program computer had first appeared in a
paper published by English mathematician Alan Mathison Turing
in 1937. In this paper, Turing described a hypothetical machine of
quite simple design that could be used to solve a wide range of logical
and mathematical problems. One significant aspect of this imaginary
Turing machine was that the tape that would run through it
would contain both information to be processed and instructions on
how to process it. The tape would thus be a type of memory device,
storing both the data and the program as sets of symbols that the
machine could “read” and understand. Turing never attempted to
construct this machine, and it was not until 1946 that he developed a
design for an electronic stored-program computer, a prototype of
which was built in 1950.
In the meantime, John von Neumann, a Hungarian American
mathematician acquainted with Turing’s ideas, joined Eckert and
Mauchly in 1944 and contributed to the design of ENIAC’s successor,
the Electronic Discrete Variable Automatic Computer (EDVAC), another
project financed by the Army. The EDVAC was the first computer
designed to incorporate the concept of the stored program.

106 / BINAC computer
In March of 1946, Eckert and Mauchly, frustrated by a controversy
over patent rights for the ENIAC, resigned from the
Moore School. Several months later, they formed the Philadelphiabased
Electronic Control Company on the strength of a contract
from the National Bureau of Standards and the Census Bureau to
build a much grander computer, the Universal Automatic Computer
(UNIVAC). They thus abandoned the EDVAC project, which
was finally completed by the Moore School in 1952, but they incorporated
the main features of the EDVAC into the design of the
UNIVAC.
Building the UNIVAC, however, proved to be much more involved
and expensive than anticipated, and the funds provided by
the original contract were inadequate. Eckert and Mauchly, therefore,
took on several other smaller projects in an effort to raise
funds. On October 9, 1947, they signed a contract with the Northrop
Corporation of Hawthorne, California, to produce a relatively small
computer to be used in the guidance system of a top-secret missile
called the Snark, which Northrop was building for the Air Force.
This computer, the Binary Automatic Computer (BINAC), turned
out to be Eckert and Mauchly’s first commercial sale and the first
stored-program computer completed in the United States.
The BINAC was designed to be at least a preliminary version of a
compact, airborne computer. It had two main processing units.
These contained a total of fourteen hundred vacuum tubes, a drastic
reduction from the eighteen thousand used in the ENIAC. There
were also two memory units, as well as two power supplies, an input
converter unit, and an input console, which used either a typewriter
keyboard or an encoded magnetic tape (the first time such
tape was used for computer input). Because of its dual processing,
memory, and power units, the BINAC was actually two computers,
each of which would continually check its results against those of
the other in an effort to identify errors.
The BINAC became operational in August, 1949. Public demonstrations
of the computer were held in Philadelphia from August 18
through August 20.

Impact
The design embodied in the BINAC is the real source of its significance.
It demonstrated successfully the benefits of the dual processor
design for minimizing errors, a feature adopted in many subsequent
computers. It showed the suitability of magnetic tape as an
input-output medium. Its most important new feature was its ability
to store programs in its relatively spacious memory, the principle
that Eckert, Mauchly, and von Neumann had originally designed
into the EDVAC. In this respect, the BINAC was a direct descendant
of the EDVAC.
In addition, the stored-program principle gave electronic computers
new powers, quickness, and automatic control that, as they
have continued to grow, have contributed immensely to the aura of
intelligence often associated with their operation.
The BINAC successfully demonstrated some of these impressive
new powers in August of 1949 to eager observers from a number of
major American corporations. It helped to convince many influential
leaders of the commercial segment of society of the promise of
electronic computers. In doing so, the BINAC helped to ensure the
further evolution of computers.
See also Apple II computer; BINAC computer; Colossus computer;
ENIAC computer; IBM Model 1401 computer; Personal computer;
Supercomputer; UNIVAC computer.
Further Reading
BINAC computer / 107
Macrae, Norman. John von Neumann: The Scientific Genius Who Pioneered
the Modern Computer, Game Theory, Nuclear Deterrence, and
Much More. New York: Pantheon Books, 1992.
Spencer, Donald D. Great Men and Women of Computing. 2d ed. Ormond
Beach, Fla.: Camelot Publishing, 1999.
Zientara, Marguerite. The History of Computing: A Biographical Portrait
of the Visionaries Who Shaped the Destiny of the Computer Industry.
Framingham, Mass.: CW Communications, 1981.

108
Birth control pill
Birth control pill
The invention: An orally administered drug that inhibits ovulation
in women, thereby greatly reducing the chance of pregnancy.
The people behind the invention:
Gregory Pincus (1903-1967), an American biologist
Min-Chueh Chang (1908-1991), a Chinese-born reproductive
biologist
John Rock (1890-1984), an American gynecologist
Celso-Ramon Garcia (1921- ), a physician
Edris Rice-Wray (1904- ), a physician
Katherine Dexter McCormick (1875-1967), an American
millionaire
Margaret Sanger (1879-1966), an American activist
An Ardent Crusader
Margaret Sanger was an ardent crusader for birth control and
family planning. Having decided that a foolproof contraceptive was
necessary, Sanger met with her friend, the wealthy socialite Katherine
Dexter McCormick. A 1904 graduate in biology from the Massachusetts
Institute of Technology, McCormick had the knowledge
and the vision to invest in biological research. Sanger arranged a
meeting between McCormick and Gregory Pincus, head of the
Worcester Institutes of Experimental Biology. After listening to Sanger’s
pleas for an effective contraceptive and McCormick’s offer of financial
backing, Pincus agreed to focus his energies on finding a pill
that would prevent pregnancy.
Pincus organized a team to conduct research on both laboratory
animals and humans. The laboratory studies were conducted under
the direction of Min-Chueh Chang, a Chinese-born scientist who
had been studying sperm biology, artificial insemination, and in vitro
fertilization. The goal of his research was to see whether pregnancy
might be prevented by manipulation of the hormones usually
found in a woman.

It was already known that there was one time when a woman
could not become pregnant—when she was already pregnant. In
1921, Ludwig Haberlandt, an Austrian physiologist, had transplanted
the ovaries from a pregnant rabbit into a nonpregnant one.
The latter failed to produce ripe eggs, showing that some substance
from the ovaries of a pregnant female prevents ovulation. This substance
was later identified as the hormone progesterone by George
W. Corner, Jr., and Willard M. Allen in 1928.
If progesterone could inhibit ovulation during pregnancy, maybe
progesterone treatment could prevent ovulation in nonpregnant females
as well. In 1937, this was shown to be the case by scientists
from the University of Pennsylvania, who prevented ovulation in
rabbits with injections of progesterone. It was not until 1951, however,
when Carl Djerassi and other chemists devised inexpensive
ways of producing progesterone in the laboratory, that serious consideration
was given to the medical use of progesterone. The synthetic
version of progesterone was called “progestin.”
Testing the Pill
Birth control pill / 109
In the laboratory, Chang tried more than two hundred different
progesterone and progestin compounds, searching for one that
would inhibit ovulation in rabbits and rats. Finally, two compounds
were chosen: progestins derived from the root of a wild Mexican
yam. Pincus arranged for clinical tests to be carried out by Celso-
Ramon Garcia, a physician, and John Rock, a gynecologist.
Rock had already been conducting experiments with progesterone
as a treatment for infertility. The treatment was effective in some
women but required that large doses of expensive progesterone be
injected daily. Rock was hopeful that the synthetic progestin that
Chang had found effective in animals would be helpful in infertile
women as well. With Garcia and Pincus, Rock treated another
group of fifty infertile women with the synthetic progestin. After
treatment ended, seven of these previously infertile women became
pregnant within half a year. Garcia, Pincus, and Rock also took several
physiological measurements of the women while they were
taking the progestin and were able to conclude that ovulation did
not occur while the women were taking the progestin pill.

(Library of Congess)
110 / Birth control pill
Margaret Sanger
Margaret Louise Higgins saw her mother die at the age of
only fifty. The cause was tuberculosis, but Margaret, the sixth of
eleven children, was convinced her mother’s string of pregnancies
was what killed her. Her crusade to liberate women from
the burden of unwanted, dangerous pregnancies lasted the rest
of her life.
Born in Corning, New York, in 1879, she went to Claverack
College and Hudson River Institute and joined a nursing program
at White Plains Hospital, graduating in 1900.
Two years later she married William Sanger, an architect
and painter. They moved into New York City in
1910 and became part of Greenwich Village’s community
of left-wing intellectuals, artists, and activists,
such as John Reed, Upton Sinclair, and Emma
Goldman. She used her free time to support liberal
reform causes, participating in labor actions of the Industrial
Workers of the World. Working as a visiting
nurse, she witnessed the health problems among poor
women caused by poor hygiene and frequent pregnancies.
In 1912 she test this began a newspaper column, “What
Every Girl Should Know,” about reproductive health and education.
The authorities tried to suppress some of the columns as
obscene—for instance, one explaining venereal disease—but
Sanger was undaunted. In 1914, she launched The Woman Rebel,
a magazine promoting women’s liberation and birth control.
From then on, although threatened with legal action and jail,
she vigorously fought the political battles for birth control She
published books, lectured, took part in demonstrations, opened
a birth control clinic in Brooklyn (the nation’s first), started the
Birth Control Federation of American (later renamed Planned
Parenthood Federation of America), and traveled overseas to
promote birth control in order to improve the standard of living
in Third World countries and to curb population growth.
Sanger was not an inventor, but she contributed ideas to the
invention of various birth control devices and in the 1950’s
found the money needed for the research and development of
oral contraceptives at the Worcester Foundation for Experimental
Biology, which produced the first birth control pill. She died
in Tucson, Arizona, in 1966.

Having shown that the hormone could effectively prevent ovulation
in both animals and humans, the investigators turned their attention
back to birth control. They were faced with several problems:
whether side effects might occur in women using progestins for a
long time, and whether women would remember to take the pill day
after day, for months or even years. To solve these problems, the birth
control pill was tested on a large scale. Because of legal problems in
the United States, Pincus decided to conduct the test in Puerto Rico.
The test started in April of 1956. Edris Rice-Wray, a physician,
was responsible for the day-to-day management of the project. As
director of the Puerto Rico Family Planning Association, she had
seen firsthand the need for a cheap, reliable contraceptive. The
women she recruited for the study were married women from a
low-income population living in a housing development in Río
Piedras, a suburb of San Juan. Word spread quickly, and soon
women were volunteering to take the pill that would prevent pregnancy.
In the first study, 221 women took a pill containing 10 milligrams
of progestin and 0.15 milligrams of estrogen. (The estrogen
was added to help control breakthrough bleeding.)
Results of the test were reported in 1957. Overall, the pill proved
highly effective in preventing conception. None of the women
who took the pill according to directions became pregnant, and
most women who wanted to get pregnant after stopping the pill
had no difficulty. Nevertheless, 17 percent of the women had some
unpleasant reactions, such as nausea or dizziness. The scientists
believed that these mild side effects, as well as one death from congestive
heart failure, were unrelated to the use of the pill.
Even before the final results were announced, additional field
tests were begun. In 1960, the U.S. Food and Drug Administration
(FDA) approved the use of the pill developed by Pincus and his collaborators
as an oral contraceptive.
Consequences
Birth control pill / 111
Within two years of approval by the FDA, more than a million
women in the United States were using the birth control pill. New
contraceptives were developed in the 1960’s and 1970’s, but the
birth control pill remains the most widely used method of prevent-

112 / Birth control pill
ing pregnancy. More than 60
million women use the pill
worldwide.
The greatest impact of the
pill has been in the social and
political world. Before Sanger
began the push for the pill,
birth control was regarded often
as socially immoral and
often illegal as well. Women
in those post-World War II
years were expected to have
a lifelong career as a mother
to their many children.
With the advent of the pill,
a radical change occurred
in society’s attitude toward
women’s work. Women had in-
creased freedom to work and enter careers previously closed to them
because of fears that they might get pregnant. Women could control
more precisely when they would get pregnant and how many children
they would have. The women’s movement of the 1960’s—with its
change to more liberal social and sexual values—gained much of its
strength from the success of the birth control pill.
See also Abortion pill; Amniocentesis; Artificial hormone; Genetically
engineered insulin; Mammography; Syphilis test; Ultrasound.
Further Reading
Dispensers designed to help users keep track of
the days on which they take their pills. (Image
Club Graphics)
DeJauregui, Ruth. One Hundred Medical Milestones That Shaped World
History. San Mateo, Calif.: Bluewood Books, 1998.
Tone, Andrea. Devices and Desires: A History of Contraceptives in America.
New York: Hill and Wang, 2001.
Watkins, Elizabeth Siegel. On the Pill: A Social History of Oral Contraceptives,
1950-1970. Baltimore: Johns Hopkins University Press, 1998.

Blood transfusion
Blood transfusion
The invention: A technique that greatly enhanced surgery patients’
chances of survival by replenishing the blood they lose in
surgery with a fresh supply.
The people behind the invention:
Charles Drew (1904-1950), American pioneer in blood
transfusion techniques
George Washington Crile (1864-1943), an American surgeon,
author, and brigadier general in the U.S. Army Medical
Officers’ Reserve Corps
Alexis Carrel (1873-1944), a French surgeon
Samuel Jason Mixter (1855-1923), an American surgeon
Nourishing Blood Transfusions
113
It is impossible to say when and where the idea of blood transfusion
first originated, although descriptions of this procedure are
found in ancient Egyptian and Greek writings. The earliest documented
case of a blood transfusion is that of Pope Innocent VII. In
April, 1492, the pope, who was gravely ill, was transfused with the
blood of three young boys. As a result, all three boys died without
bringing any relief to the pope.
In the centuries that followed, there were occasional descriptions
of blood transfusions, but it was not until the middle of the seventeenth
century that the technique gained popularity following the
English physician and anatomist William Harvey’s discovery of the
circulation of the blood in 1628. In the medical thought of those
times, blood transfusion was considered to have a nourishing effect
on the recipient. In many of those experiments, the human recipient
received animal blood, usually from a lamb or a calf. Blood transfusion
was tried as a cure for many different diseases, mainly those
that caused hemorrhages, as well as for other medical problems and
even for marital problems.
Blood transfusions were a dangerous procedure, causing many
deaths of both donor and recipient as a result of excessive blood

114 / Blood transfusion
loss, infection, passage of blood clots into the circulatory systems of
the recipients, passage of air into the blood vessels (air embolism),
and transfusion reaction as a result of incompatible blood types. In
the mid-nineteenth century, blood transfusions from animals to humans
stopped after it was discovered that the serum of one species
agglutinates and dissolves the blood cells of other species. A sharp
drop in the use of blood transfusion came with the introduction of
physiologic salt solution in 1875. Infusion of salt solution was simple
and was safer than blood transfusion.
Direct-Connection Blood Transfusions
In 1898, when George Washington Crile began his work on blood
transfusions, the major obstacle he faced was solving the problem of
blood clotting during transfusions. He realized that salt solutions
were not helpful in severe cases of blood loss, when there is a need to
restore the patient to consciousness, steady the heart action, and raise
the blood pressure. At that time, he was experimenting with indirect
blood transfusions by drawing the blood of the donor into a vessel,
then transferring it into the recipient’s vein by tube, funnel, and cannula,
the same technique used in the infusion of saline solution.
The solution to the problem of blood clotting came in 1902 when
Alexis Carrel developed the technique of surgically joining blood
vessels without exposing the blood to air or germs, either of which
can lead to clotting. Crile learned this technique from Carrel and
used it to join the peripheral artery in the donor to a peripheral vein
of the recipient. Since the transfused blood remained sealed in the
inner lining of the vessels, blood clotting did not occur.
The first human blood transfusion of this type was performed by
Crile in December, 1905. The patient, a thirty-five-year-old woman,
was transfused by her husband but died a few hours after the procedure.
The second, but first successful, transfusion was performed on
August 8, 1906. The patient, a twenty-three-year-old male, suffered
from severe hemorrhaging following surgery to remove kidney
stones. After all attempts to stop the bleeding were exhausted with
no results, and the patient was dangerously weak, transfusion was
considered as a last resort. One of the patient’s brothers was the do-

Charles Drew
Blood transfusion / 115
While he was still in medical school, Charles Richard Drew
saw a man’s life saved with a blood transfusion. He also saw patients
die because suitable donors could not be found. Impressed
by both the life-saving power of transfusions and the
dire need for more of them, Drew devoted his career to improving
the nation’s blood supply. His inventions saved untold
thousands of lives, especially during World War II, before artificial
blood was developed.
Born in 1904 in Washington, D.C., Drew was a star athlete in
high school, in Amherst College—from which he graduated in
1926—and even in medical school at McGill University
in Montreal from 1928 to 1933. He returned to the
U.S. capital to become a resident in Freedmen’s Hospital
of Howard University. While there he invented a
method for separating plasma from whole blood and
discovered that it was not necessary to recombine the
plasma and red blood cells for transfusion. Plasma
alone was sufficient, and by drying or and freezing it,
the plasma remained fresh enough over long periods
to act as an emergency reserve. In 1938 Drew took a
fellowship in blood research at Columbia Presbyterian Hospital
in New York City. Employing his plasma preservation methods,
he opened the first blood bank and wrote a dissertation on his
techniques. He became the first African American to earn a
Doctor of Science degree from Columbia University in 1940.
He organized another blood bank, this one in Great Britain,
and in 1941 was appointed director of the American Red Cross
blood donor project. However, Drew learned to his disgust that
the Red Cross and U.S. government would not allow blood
from African Americans and Caucasians to be mixed in the
blood bank. There was no scientific reason for such segregation.
Bias prevailed. Drew angrily denounced the policy at a press
conference and resigned from the Red Cross.
He went back to Howard University as head of surgery and,
later, director of Freedmen’s Hospital. Drew died in 1950 following
an automobile accident.
nor. Following the transfusion, the patient showed remarkable recovery
and was strong enough to withstand surgery to remove the
kidney and stop the bleeding. When his condition deteriorated a
(Associated Publishers)

116 / Blood transfusion
few days later, another transfusion was done. This time, too, he
showed remarkable improvement, which continued until his complete
recovery.
For his first transfusions, Crile used the Carrel suture method,
which required using very fine needles and thread. It was a very
delicate and time-consuming procedure. At the suggestion of Samuel
Jason Mixter, Crile developed a new method using a short tubal
device with an attached handle to connect the blood vessels. By this
method, 3 or 4 centimeters of the vessels to be connected were surgically
exposed, clamped, and cut, just as under the previous method.
Yet, instead of suturing of the blood vessels, the recipient’s vein was
passed through the tube and then cuffed back over the tube and tied
to it. Then the donor’s artery was slipped over the cuff. The clamps
were opened, and blood was allowed to flow from the donor to the
recipient. In order to accommodate different-sized blood vessels,
tubes of four different sizes were made, ranging in diameter from
1.5 to 3 millimeters.
Impact
Crile’s method was the preferred method of blood transfusion
for a number of years. Following the publication of his book on
transfusion, a number of modifications to the original method were
published in medical journals. In 1913, Edward Lindeman developed
a method of transfusing blood simply by inserting a needle
through the patient’s skin and into a surface vein, making it for the
first time a nonsurgical method. This method allowed one to measure
the exact quantity of blood transfused. It also allowed the donor
to serve in multiple transfusions. This development opened the
field of transfusions to all physicians. Lindeman’s needle and syringe
method also eliminated another major drawback of direct
blood transfusion: the need to have both donor and recipient right
next to each other.
See also Coronary artery bypass surgery; Electrocardiogram;
Electroencephalogram; Heart-lung machine.

Further Reading
Blood transfusion / 117
English, Peter C. Shock, Physiological Surgery, and George Washington
Crile: Medical Innovation in the Progressive Era. Westport, Conn.:
Greenwood Press, 1980.
Le Vay, David, and Roy Porter. Alexis Carrel: The Perfectibility of Man.
Rockville, Md.: Kabel Publishers, 1996.
Malinin, Theodore I. Surgery and Life: The Extraordinary Career of
Alexis Carrel. New York: Harcourt Brace Jovanovich, 1979.
May, Angelo M., and Alice G. May. The Two Lions of Lyons: The Tale of
Two Surgeons, Alexis Carrel and René Leriche. Rockville, Md.: Kabel
Publishers, 1992.

118
Breeder reactor
Breeder reactor
The invention: A plant that generates electricity from nuclear fission
while creating new fuel.
The person behind the invention:
Walter Henry Zinn (1906-2000), the first director of the Argonne
National Laboratory
Producing Electricity with More Fuel
The discovery of nuclear fission involved both the discovery that
the nucleus of a uranium atom would split into two lighter elements
when struck by a neutron and the observation that additional neutrons,
along with a significant amount of energy, were released at
the same time. These neutrons might strike other atoms and cause
them to fission (split) also. That, in turn, would release more energy
and more neutrons, triggering a chain reaction as the process continued
to repeat itself, yielding a continuing supply of heat.
Besides the possibility that an explosive weapon could be constructed,
early speculation about nuclear fission included its use in
the generation of electricity. The occurrence of World War II (1939-
1945) meant that the explosive weapon would be developed first.
Both the weapons technology and the basic physics for the electrical
reactor had their beginnings in Chicago with the world’s first nuclear
chain reaction. The first self-sustaining nuclear chain reaction occurred
in a laboratory at the University of Chicago on December 2, 1942.
It also became apparent at that time that there was more than one
way to build a bomb. At this point, two paths were taken: One was
to build an atomic bomb with enough fissionable uranium in it to
explode when detonated, and another was to generate fissionable
plutonium and build a bomb. Energy was released in both methods,
but the second method also produced another fissionable substance.
The observation that plutonium and energy could be produced together
meant that it would be possible to design electric power systems
that would produce fissionable plutonium in quantities as large
as, or larger than, the amount of fissionable material consumed. This

is the breeder concept, the idea that while using up fissionable uranium
235, another fissionable element can be made. The full development
of this concept for electric power was delayed until the end of
World War II.
Electricity from Atomic Energy
Breeder reactor / 119
On August 1, 1946, the Atomic Energy Commission (AEC) was
established to control the development and explore the peaceful
uses of nuclear energy. The Argonne National Laboratory was assigned
the major responsibilities for pioneering breeder reactor
technologies. Walter Henry Zinn was the laboratory’s first director.
He led a team that planned a modest facility (Experimental Breeder
Reactor I, or EBR-I) for testing the validity of the breeding principle.
Planning for this had begun in late 1944 and grew as a natural extension
of the physics that developed the plutonium atomic bomb.
The conceptual design details for a breeder-electric reactor were
reasonably complete by late 1945. On March 1, 1949, the AEC announced
the selection of a site in Idaho for the National Reactor Station
(later to be named the Idaho National Engineering Laboratory,
or INEL). Construction at the INEL site in Arco, Idaho, began in October,
1949. Critical mass was reached in August, 1951. (“Critical
mass” is the amount and concentration of fissionable material required
to produce a self-sustaining chain reaction.)
The system was brought to full operating power, 1.1 megawatts
of thermal power, on December 19, 1951. The next day, December
20, at 11:00 a.m., steam was directed to a turbine generator. At 1:23
p.m., the generator was connected to the electrical grid at the site,
and “electricity flowed from atomic energy,” in the words of Zinn’s
console log of that day. Approximately 200 kilowatts of electric
power were generated most of the time that the reactor was run.
This was enough to satisfy the needs of the EBR-I facilities. The reactor
was shut down in 1964 after five years of use primarily as a test
facility. It had also produced the first pure plutonium.
With the first fuel loading, a conversion ratio of 1.01 was achieved,
meaning that more new fuel was generated than was consumed by
about 1 percent. When later fuel loadings were made with plutonium,
the conversion ratios were more favorable, reaching as high

120 / Breeder reactor
as 1.27. EBR-I was the first reactor to generate its own fuel and the
first power reactor to use plutonium for fuel.
The use of EBR-I also included pioneering work on fuel recovery
and reprocessing. During its five-year lifetime, EBR-I operated with
four different fuel loadings, each designed to establish specific
benchmarks of breeder technology. This reactor was seen as the first
in a series of increasingly large reactors in a program designed to
develop breeder technology. The reactor was replaced by EBR-II,
which had been proposed in 1953 and was constructed from 1955 to
1964. EBR-II was capable of producing 20 megawatts of electrical
power. It was approximately fifty times more powerful than EBR-I
but still small compared to light-water commercial reactors of 600 to
1,100 megawatts in use toward the end of the twentieth century.
Consequences
The potential for peaceful uses of nuclear fission were dramatized
with the start-up of EBR-I in 1951: It was the first in the world
to produce electricity, while also being the pioneer in a breeder reactor
program. The breeder program was not the only reactor program
being developed, however, and it eventually gave way to the
light-water reactor design for use in the United States. Still, if energy
resources fall into short supply, it is likely that the technologies first
developed with EBR-I will find new importance. In France and Japan,
commercial reactors make use of breeder reactor technology;
these reactors require extensive fuel reprocessing.
Following the completion of tests with plutonium loading in 1964,
EBR-I was shut down and placed in standby status. In 1966, it was declared
a national historical landmark under the stewardship of the
U.S. Department of the Interior. The facility was opened to the public
in June, 1975.
See also Atomic bomb; Geothermal power; Nuclear power
plant; Nuclear reactor; Solar thermal engine; Tidal power plant.

Further Reading
Breeder reactor / 121
“Breeder Trouble.” Technology Review 91, no. 5 (July, 1988).
Hippel, Frank von, and Suzanne Jones. “Birth of the Breeder.” Bulletin
of the Atomic Scientists 53, no. 5 (September/October, 1997).
Krieger, David. Splitting the Atom: A Chronology of the Nuclear Age.
Santa Barbara, Calif.: Nuclear Age Peace foundation, 1998.

122
Broadcaster guitar
Broadcaster guitar
The invention: The first commercially manufactured solid-body
electric guitar, the Broadcaster revolutionized the guitar industry
and changed the face of popular music
The people behind the invention:
Leo Fender (1909-1991), designer of affordable and easily massproduced
solid-body electric guitars
Les Paul (Lester William Polfuss, 1915- ), a legendary
guitarist and designer of solid-body electric guitars
Charlie Christian (1919-1942), an influential electric jazz
guitarist of the 1930’s
Early Electric Guitars
It has been estimated that between 1931 and 1937, approximately
twenty-seven hundred electric guitars and amplifiers were sold in
the United States. The Electro String Instrument Company, run
by Adolph Rickenbacker and his designer partners, George Beauchamp
and Paul Barth, produced two of the first commercially manufactured
electric guitars—the Rickenbacker A-22 and A-25—in
1931. The Rickenbacker models were what are known as “lap steel”
or Hawaiian guitars. A Hawaiian guitar is played with the instrument
lying flat across a guitarist’s knees. By the mid-1930’s, the Gibson
company had introduced an electric Spanish guitar, the ES-150.
Legendary jazz guitarist Charlie Christian made this model famous
while playing for Benny Goodman’s orchestra. Christian was the
first electric guitarist to be heard by a large American audience.
He became an inspiration for future electric guitarists, because he
proved that the electric guitar could have its own unique solo
sound. Along with Christian, the other electric guitar figures who
put the instrument on the musical map were blues guitarist T-Bone
Walker, guitarist and inventor Les Paul, and engineer and inventor
Leo Fender.
Early electric guitars were really no more than acoustic guitars,
with the addition of one or more pickups, which convert string vi-

ations to electrical signals that can be played through a speaker.
Amplification of a guitar made it a more assertive musical instrument.
The electrification of the guitar ultimately would make it
more flexible, giving it a more prominent role in popular music. Les
Paul, always a compulsive inventor, began experimenting with
ways of producing an electric solid-body guitar in the late 1930’s. In
1929, at the age of thirteen, he had amplified his first acoustic guitar.
Another influential inventor of the 1940’s was Paul Bigsby. He built
a prototype solid-body guitar for country music star Merle Travis in
1947. It was Leo Fender who revolutionized the electric guitar industry
by producing the first commercially viable solid-body electric
guitar, the Broadcaster, in 1948.
Leo Fender
Broadcaster guitar / 123
Leo Fender was born in the Anaheim, California, area in 1909. As
a teenager, he began to build and repair guitars. By the 1930’s,
Fender was building and renting out public address systems for
group gatherings. In 1937, after short tenures of employment with
the Division of Highways and the U.S. Tire Company, he opened a
radio repair company in Fullerton, California. Always looking to
expand and invent new and exciting electrical gadgets, Fender and
Clayton Orr “Doc” Kauffman started the K&FCompany in 1944.
Kauffman was a musician and a former employee of the Electro
String Instrument Company. TheK&FCompany lasted until 1946
and produced steel guitars and amplifiers. After that partnership
ended, Fender founded the Fender Electric Instruments Company.
With the help of George Fullerton, who joined the company in
1948, Fender developed the Fender Broadcaster. The body of the
Broadcaster was made of a solid plank of ash wood. The corners of
the ash body were rounded. There was a cutaway located under the
joint with the solid maple neck, making it easier for the guitarist to
access the higher frets. The maple neck was bolted to the body of the
guitar, which was unusual, since most guitar necks prior to the
Broadcaster had been glued to the body. Frets were positioned directly
into designed cuts made in the maple of the neck. The guitar
had two pickups.
The Fender Electric Instruments Company made fewer than one

124 / Broadcaster guitar
thousand Broadcasters. In 1950, the name of the guitar was changed
from the Broadcaster to the Telecaster, as the Gretsch company had
already registered the name Broadcaster for some of its drums and
banjos. Fender decided not to fight in court over use of the name.
Leo Fender has been called the Henry Ford of the solid-body
electric guitar, and the Telecaster became known as the Model T of
the industry. The early Telecasters sold for $189.50. Besides being inexpensive,
the Telecaster was a very durable instrument. Basically,
the Telecaster was a continuation of the Broadcaster. Fender did not
file for a patent on its unique bridge pickup until January 13, 1950,
and he did not file for a patent on the Telecaster’s unique body
shape until April 3, 1951.
In the music industry during the late 1940’s, it was important for
a company to unveil new instruments at trade shows. At this time,
there was only one important trade show, sponsored by the National
Association of Music Merchants. The Broadcaster was first
sprung on the industry at the 1948 trade show in Chicago. The industry
had seen nothing like this guitar ever before. This new guitar
existed only to be amplified; it was not merely an acoustic guitar
that had been converted.
Impact
The Telecaster, as it would be called after 1950, remained in continuous
production for more years than any other guitar of its type
and was one of the industry’s best sellers. From the beginning, it
looked and sounded unique. The electrified acoustic guitars had a
mellow woody tone, whereas the Telecaster had a clean twangy
tone. This tone made it popular with country and blues guitarists.
The Telecaster could also be played at higher volume than previous
electric guitars.
Because Leo Fender attempted something revolutionary by introducing
an electric solid-body guitar, there was no guarantee that
his business venture would succeed. Fender Electric Instruments
Company had fifteen employees in 1947. At times, during the early
years of the company, it looked as though Fender’s dreams would
not come to fruition, but the company persevered and grew. Between
1948 and 1955 with an increase of employees, the company

was able to produce ten thousand Broadcaster/Telecaster guitars.
Fender had taken a big risk, but it paid off enormously. Between
1958 and the mid-1970’s, Fender produced more than 250,000 Telecasters.
Other guitar manufacturers were placed in a position of
having to catch up. Fender had succeeded in developing a process
by which electric solid-body guitars could be manufactured profitably
on a large scale.
Early Guitar Pickups
Broadcaster guitar / 125
The first pickups used on a guitar can be traced back to the 1920’s
and the efforts of Lloyd Loar, but there was not strong interest on the
part of the American public for the guitar to be amplified. The public
did not become intrigued until the 1930’s. Charlie Christian’s
electric guitar performances with Benny Goodman woke up the
public to the potential of this new and exciting sound. It was not until
the 1950’s, though, that the electric guitar became firmly established.
Leo Fender was the right man in the right place. He could not
have known that his Fender guitars would help to usher in a whole
new musical landscape. Since the electric guitar was the newest
member of the family of guitars, it took some time for musical audiences
to fully appreciate what it could do. The electric solid-body
guitar has been called a dangerous, uncivilized instrument. The
youth culture of the 1950’s found in this new guitar a voice for their
rebellion. Fender unleashed a revolution not only in the construction
of a guitar but also in the way popular music would be approached
henceforth.
Because of the ever-increasing demand for the Fender product,
Fender Sales was established as a separate distribution company in
1953 by Don Randall. Fender Electric Instruments Company had fifteen
employees in 1947, but by 1955, the company employed fifty
people. By 1960, the number of employees had risen to more than
one hundred. Before Leo Fender sold the company to CBS on January
4, 1965, for $13 million, the company occupied twenty-seven
buildings and employed more than five hundred workers.
Always interested in finding new ways of designing a more nearly
perfect guitar, Leo Fender again came up with a remarkable guitar in
1954, with the Stratocaster. There was talk in the guitar industry that

126 / Broadcaster guitar
Charlie Christian
Charlie Christian (1919-1942) did not invent the electric guitar,
but he did pioneer its use. He was born to music, and for
jazz aficionados he quickly developed into a legend, not only
establishing a new solo instrument but also helping to invent a
whole new type of jazz.
Christian grew up in Texas, surrounded by a family of professional
musicians. His parents and two brothers played trumpet,
guitar, and piano, and sang, and Charlie was quick to imitate
them. As a boy he made his own guitars out of cigar boxes
and, according to a childhood friend, novelist Ralph Ellison,
wowed his friends at school with his riffs. When he first heard
an electric guitar in the mid-1930’s, he made that his own, too.
The acoustic guitar had been only a backup instrument in
jazz because it was too quiet to soar in solos. In 1935, Eddie Durham
found that electric guitars could swing side by side with
louder instruments. Charlie, already an experienced performer
with acoustic guitar and bass, immediately recognized the power
and range of subtle expression possible with the electrified instrument.
He bought a Gibson ES-150 and began to make musical
history with his improvisations.
He impressed producer John Hammond, who introduced
him to big-band leader Benny Goodman in 1939. Notoriously
hard to please, Goodman rejected Christian after an audition.
However, Hammond later sneaked him on stage while the
Goodman band was performing. Outraged, Goodman segued
into a tune he was sure Christian did not know, “Rose Room.”
Christian was undaunted. He delivered an astonishingly inventive
solo, and Goodman was won over despite himself. Christian’s
ensuing tenure with Goodman’s band brought electric
guitar solos into the limelight.
However, it was during after-hours jam sessions at the Hotel
Cecil in New York that Christian left his stylistic imprint on
jazz. Including such jazz greats as Joe Guy, Thelonious Monk,
and Kenny Clarke, the groups played around with new sounds.
Out of these sessions bebop was born, and Christian was a central
figure. Sick with tuberculosis, he had to quit playing in 1941
and died the following spring, only twenty-five years old.

Fender had gone too far with the introduction of the Stratocaster, but
it became a huge success because of its versatility. It was the first commercial
solid-body electric guitar to have three pickups and a vibrato
bar. It was also easier to play than the Telecaster because of its double
cutaway, contoured body, and scooped back. The Stratocaster sold
for $249.50. Since its introduction, the Stratocaster has undergone
some minor changes, but Fender and his staff basically got it right the
first time.
The Gibson company entered the solid-body market in 1952 with
the unveiling of the “Les Paul” model. After the Telecaster, the Les
Paul guitar was the next significant solid-body to be introduced. Les
Paul was a legendary guitarist who also had been experimenting
with electric guitar designs for many years. The Gibson designers
came up with a striking model that produced a thick rounded tone.
Over the years, the Les Paul model has won a loyal following.
The Precision Bass
Broadcaster guitar / 127
In 1951, Leo Fender introduced another revolutionary guitar, the
Precision bass. At a cost of $195.50, the first electric bass would go on
to dominate the market. The Fender company has manufactured numerous
guitar models over the years, but the three that stand above
all others in the field are the Telecaster, the Precision bass, and the
Stratocaster. The Telecaster is considered to be more of a workhorse,
whereas the Stratocaster is thought of as the thoroughbred of electric
guitars. The Precision bass was in its own right a revolutionary guitar.
With a styling that had been copied from the Telecaster, the Precision
freed musicians from bulky oversized acoustic basses, which
were prone to feedback. The name Precision had meaning. Fender’s
electric bass made it possible, with its frets, for the precise playing of
notes; many acoustic basses were fretless. The original Precision bass
model was manufactured from 1951 to 1954. The next version lasted
from 1954 until June of 1957. The Precision bass that went into production
in June, 1957, with its split humbucking pickup, continued to
be the standard electric bass on the market into the 1990’s.
By 1964, the Fender Electric Instruments Company had grown
enormously. In addition to Leo Fender, a number of crucial people
worked for the organization, including George Fullerton and Don

128 / Broadcaster guitar
Randall. Fred Tavares joined the company’s research and development
team in 1953. In May, 1954, Forrest White became Fender’s
plant manager. All these individuals played vital roles in the success
of Fender, but the driving force behind the scene was always
Leo Fender. As Fender’s health deteriorated, Randall commenced
negotiations with CBS to sell the Fender company. In January, 1965,
CBS bought Fender for $13 million. Eventually, Leo Fender regained
his health, and he was hired as a technical adviser by CBS/Fender.
He continued in this capacity until 1970. He remained determined
to create more guitar designs of note. Although he never again produced
anything that could equal his previous success, he never
stopped trying to attain a new perfection of guitar design.
Fender died on March 21, 1991, in Fullerton, California. He had
suffered for years from Parkinson’s disease, and he died of complications
from the disease. He is remembered for his Broadcaster/
Telecaster, Precision bass, and Stratocaster, which revolutionized
popular music. Because the Fender company was able to mass produce
these and other solid-body electric guitars, new styles of music
that relied on the sound made by an electric guitar exploded onto
the scene. The electric guitar manufacturing business grew rapidly
after Fender introduced mass production. Besides American companies,
there are guitar companies that have flourished in Europe
and Japan.
The marriage between rock music and solid-body electric guitars
was initiated by the Fender guitars. The Telecaster, Precision bass,
and Stratocaster become synonymous with the explosive character
of rock and roll music. The multi-billion-dollar music business can
point to Fender as the pragmatic visionary who put the solid-body
electric guitar into the forefront of the musical scene. His innovative
guitars have been used by some of the most important guitarists of
the rock era, including Jimi Hendrix, Eric Clapton, and Jeff Beck.
More important, Fender guitars have remained bestsellers with
the public worldwide. Amateur musicians purchased them by the
thousands for their own entertainment. Owning and playing a
Fender guitar, or one of the other electric guitars that followed, allowed
these amateurs to feel closer to their musician idols. A large
market for sheet music from popular artists also developed.
In 1992, Fender was inducted into the Rock and Roll Hall of

Fame. He is one of the few non-musicians ever to be inducted. The
sound of an electric guitar is the sound of exuberance, and since the
Broadcaster was first unveiled in 1948, that sound has grown to be
pervasive and enormously profitable.
See also Cassette recording; Dolby noise reduction; Electronic
synthesizer.
Further Reading
Broadcaster guitar / 129
Bacon, Tony, and Paul Day. The Fender Book. San Francisco: GPI
Books, 1992.
Brosnac, Donald, ed. Guitars Made by the Fender Company. Westport,
Conn.: Bold Strummer, 1986.
Freeth, Nick. The Electric Guitar. Philadelphia: Courage Books, 1999.
Trynka, Paul. The Electric Guitar: An Illustrated History. San Francisco:
Chronicle Books, 1995.
Wheeler, Tom. American Guitars: An Illustrated History. New York:
Harper & Row, 1982.
_____. “Electric Guitars.” In The Guitar Book: A Handbook for Electric
and Acoustic Guitarists. New York: Harper & Row, 1974.

130
Brownie camera
Brownie camera
The invention: The first inexpensive and easy-to-use camera available
to the general public, the Brownie revolutionized photography
by making it possible for every person to become a photographer.
The people behind the invention:
George Eastman (1854-1932), founder of the Eastman Kodak
Company
Frank A. Brownell, a camera maker for the Kodak Company
who designed the Brownie
Henry M. Reichenbach, a chemist who worked with Eastman to
develop flexible film
William H. Walker, a Rochester camera manufacturer who
collaborated with Eastman
A New Way to Take Pictures
In early February of 1900, the first shipments of a new small box
camera called the Brownie reached Kodak dealers in the United
States and England. George Eastman, eager to put photography
within the reach of everyone, had directed Frank Brownell to design
a small camera that could be manufactured inexpensively but that
would still take good photographs.
Advertisements for the Brownie proclaimed that everyone—
even children—could take good pictures with the camera. The
Brownie was aimed directly at the children’s market, a fact indicated
by its box, which was decorated with drawings of imaginary
elves called “Brownies” created by the Canadian illustrator Palmer
Cox. Moreover, the camera cost only one dollar.
The Brownie was made of jute board and wood, with a hinged
back fastened by a sliding catch. It had an inexpensive two-piece
glass lens and a simple rotary shutter that allowed both timed and
instantaneous exposures to be made. With a lens aperture of approximately
f14 and a shutter speed of approximately 1/50 of a second,
the Brownie was certainly capable of taking acceptable snap-

Brownie camera / 131
shots. It had no viewfinder; however, an optional clip-on reflecting
viewfinder was available. The camera came loaded with a six-exposure
roll of Kodak film that produced square negatives 2.5 inches on
a side. This film could be developed, printed, and mounted for forty
cents, and a new roll could be purchased for fifteen cents.
George Eastman’s first career choice had been banking, but when
he failed to receive a promotion he thought he deserved, he decided
to devote himself to his hobby, photography. Having worked with a
rigorous wet-plate process, he knew why there were few amateur
photographers at the time—the whole process, from plate preparation
to printing, was too expensive and too much trouble. Even so,
he had already begun to think about the commercial possibilities of
photography; after reading of British experiments with dry-plate
technology, he set up a small chemical laboratory and came up with
a process of his own. The Eastman Dry Plate Company became one
of the most successful producers of gelatin dry plates.
Dry-plate photography had attracted more amateurs, but it was
still a complicated and expensive hobby. Eastman realized that the
number of photographers would have to increase considerably if
the market for cameras and supplies were to have any potential. In
the early 1880’s, Eastman first formulated the policies that would
make the Eastman Kodak Company so successful in years to come:
mass production, low prices, foreign and domestic distribution, and
selling through extensive advertising and by demonstration.
In his efforts to expand the amateur market, Eastman first tackled
the problem of the glass-plate negative, which was heavy, fragile,
and expensive to make. By 1884, his experiments with paper
negatives had been successful enough that he changed the name of
his company to The Eastman Dry Plate and Film Company. Since
flexible roll film needed some sort of device to hold it steady in the
camera’s focal plane, Eastman collaborated with William Walker
to develop the Eastman-Walker roll-holder. Eastman’s pioneering
manufacture and use of roll films led to the appearance on the market
in the 1880’s of a wide array of hand cameras from a number of
different companies. Such cameras were called “detective cameras”
because they were small and could be used surreptitiously. The
most famous of these, introduced by Eastman in 1888, was named
the “Kodak”—a word he coined to be terse, distinctive, and easily

132 / Brownie camera
pronounced in any language. This camera’s simplicity of operation
was appealing to the general public and stimulated the growth of
amateur photography.
The Camera
The Kodak was a box about seven inches long and four inches
wide, with a one-speed shutter and a fixed-focus lens that produced
reasonably sharp pictures. It came loaded with enough roll film to
make one hundred exposures. The camera’s initial price of twentyfive
dollars included the cost of processing the first roll of film; the
camera also came with a leather case and strap. After the film was
exposed, the camera was mailed, unopened, to the company’s plant
in Rochester, New York, where the developing and printing were
done. For an additional ten dollars, the camera was reloaded and
sent back to the customer.
The Kodak was advertised in mass-market publications, rather
than in specialized photographic journals, with the slogan: “You
press the button, we do the rest.” With his introduction of a camera
that was easy to use and a service that eliminated the need to know
anything about processing negatives, Eastman revolutionized the
photographic market. Thousands of people no longer depended
upon professional photographers for their portraits but instead
learned to make their own. In 1892, the Eastman Dry Plate and Film
Company became the Eastman Kodak Company, and by the mid-
1890’s, one hundred thousand Kodak cameras had been manufactured
and sold, half of them in Europe by Kodak Limited.
Having popularized photography with the first Kodak, in 1900
Eastman turned his attention to the children’s market with the introduction
of the Brownie. The first five thousand cameras sent to
dealers were sold immediately; by the end of the following year, almost
a quarter of a million had been sold. The Kodak Company organized
Brownie camera clubs and held competitions specifically
for young photographers. The Brownie came with an instruction
booklet that gave children simple directions for taking successful
pictures, and “The Brownie Boy,” an appealing youngster who
loved photography, became a standard feature of Kodak’s advertisements.

Impact
Brownie camera / 133
Eastman followed the success of the first Brownie by introducing
several additional models between 1901 and 1917. Each was a more
elaborate version of the original. These Brownie box cameras were
on the market until the early 1930’s, and their success inspired other
companies to manufacture box cameras of their own. In 1906, the
Ansco company produced the Buster Brown camera in three sizes
that corresponded to Kodak’s Brownie camera range; in 1910 and
1914, Ansco made three more versions. The Seneca company’s
Scout box camera, in three sizes, appeared in 1913, and Sears Roebuck’s
Kewpie cameras, in five sizes, were sold beginning in 1916.
In England, the Houghtons company introduced its first Scout camera
in 1901, followed by another series of four box cameras in 1910
sold under the Ensign trademark. Other English manufacturers of
box cameras included the James Sinclair company, with its Traveller
Una of 1909, and the Thornton-Pickard company, with a Filma camera
marketed in four sizes in 1912.
After World War I ended, several series of box cameras were
manufactured in Germany by companies that had formerly concentrated
on more advanced and expensive cameras. The success of
box cameras in other countries, led by Kodak’s Brownie, undoubtedly
prompted this trend in the German photographic industry. The
Ernemann Film K series of cameras in three sizes, introduced in
1919, and the all-metal Trapp Little Wonder of 1922 are examples of
popular German box cameras.
In the early 1920’s, camera manufacturers began making boxcamera
bodies from metal rather than from wood and cardboard.
Machine-formed metal was less expensive than the traditional handworked
materials. In 1924, Kodak’s two most popular Brownie sizes
appeared with aluminum bodies.
In 1928, Kodak Limited of England added two important new
features to the Brownie—a built-in portrait lens, which could be
brought in front of the taking lens by pressing a lever, and camera
bodies in a range of seven different fashion colors. The Beau
Brownie cameras, made in 1930, were the most popular of all the
colored box cameras. The work of Walter Dorwin Teague, a leading
American designer, these cameras had an Art Deco geometric pat-

134 / Brownie camera
tern on the front panel, which was enameled in a color matching the
leatherette covering of the camera body. Several other companies,
including Ansco, again followed Kodak’s lead and introduced their
own lines of colored cameras.
In the 1930’s, several new box cameras with interesting features appeared,
many manufactured by leading film companies. In France, the
Lumiere Company advertised a series of box cameras—the Luxbox,
Scoutbox, and Lumibox—that ranged from a basic camera to one with
an adjustable lens and shutter. In 1933, the German Agfa company restyled
its entire range of box cameras, and in 1939, the Italian Ferrania
company entered the market with box cameras in two sizes. In 1932,
Kodak redesigned its Brownie series to take the new 620 roll film,
which it had just introduced. This film and the new Six-20 Brownies inspired
other companies to experiment with variations of their own;
some box cameras, such as the Certo Double-box, the Coronet Every
Distance, and the Ensign E-20 cameras, offered a choice of two picture
formats.
Another new trend was a move toward smaller-format cameras
using standard 127 roll film. In 1934, Kodak marketed the small
Baby Brownie. Designed by Teague and made from molded black
plastic, this little camera with a folding viewfinder sold for only one
dollar—the price of the original Brownie in 1900.
The Baby Brownie, the first Kodak camera made of molded plastic,
heralded the move to the use of plastic in camera manufacture.
Soon many others, such as the Altissa series of box cameras and the
Voigtlander Brilliant V/6 camera, were being made from this new
material.
Later Trends
By the late 1930’s, flashbulbs had replaced flash powder for taking
pictures in low light; again, the Eastman Kodak Company led
the way in introducing this new technology as a feature on the inexpensive
box camera. The Falcon Press-Flash, marketed in 1939, was
the first mass-produced camera to have flash synchronization and
was followed the next year by the Six-20 Flash Brownie, which had a
detachable flash gun. In the early 1940’s, other companies, such as
Agfa-Ansco, introduced this feature on their own box cameras.

George Eastman
Brownie camera / 135
Frugal, bold, practical, generous to those who were loyal,
impatient with dissent, and possessing a steely determination,
George Eastman (1854-1932) rose to become one of the richest
people of his generation. He abhorred poverty and did his best
to raise others from it as well.
At age fourteen, when his father died, Eastman
had to drop out of school to support his mother and
sister. The missed opportunity for an education and
the struggle to earn a living shaped his outlook. He
worked at an insurance agency and then at a bank,
keeping careful record of the money he earned. By
the time he was twenty-five he had saved three thousand
dollars and found his job as a banker to be unrewarding.
As a teenager, he had taught himself photography.
However, that was only a start. He taught himself the physics
and chemistry of photography too—and enough French and
German to read the latest foreign scientific journals. His purpose
was practical, to make cameras cheap and easy to use so
that average people could own them. This launched him on the
career of invention and business that took him away from banking
and made his fortune. At the same time he remembered his
origins and family. Out of his first earnings, he bought photographs
for his mother and a favorite teacher. He never stopped
giving. At the company he founded, he gave substantial raises
to employees, reduced their hours, and installed safety equipment,
a medical department, and a lunch room. He gave millions
to the Hampton Institute, Tuskegee Institute, Massachusetts
Institute of Technology, and University of Rochester, while
also establishing dental clinics for the poor.
In his old age he found he could no longer keep up with his
younger scientific and business colleagues. In 1932, leaving behind
a note that asked, simply, “My work is done, why wait?”
he committed suicide. Even then he continued to give. His will
left most of his vast fortune to charities.
In the years after World War II, the box camera evolved into an
eye-level camera, making it more convenient to carry and use.
Many amateur photographers, however, still had trouble handling
(Smithsonian Institution)

136 / Brownie camera
paper-backed roll film and were taking their cameras back to dealers
to be unloaded and reloaded. Kodak therefore developed a new
system of film loading, using the Kodapak cartridge, which could
be mass-produced with a high degree of accuracy by precision plastic-molding
techniques. To load the camera, the user simply opened
the camera back and inserted the cartridge. This new film was introduced
in 1963, along with a series of Instamatic cameras designed
for its use. Both were immediately successful.
The popularity of the film cartridge ended the long history of the
simple and inexpensive roll film camera. The last English Brownie
was made in 1967, and the series of Brownies made in the United
States was discontinued in 1970. Eastman’s original marketing strategy
of simplifying photography in order to increase the demand for
cameras and film continued, however, with the public’s acceptance
of cartridge-loading cameras such as the Instamatic.
From the beginning, Eastman had recognized that there were
two kinds of photographers other than professionals. The first, he
declared, were the true amateurs who devoted time enough to acquire
skill in the complex processing procedures of the day. The second
were those who merely wanted personal pictures or memorabilia
of their everyday lives, families, and travels. The second class,
he observed, outnumbered the first by almost ten to one. Thus, it
was to this second kind of amateur photographer that Eastman had
appealed, both with his first cameras and with his advertising slogan,
“You press the button, we do the rest.” Eastman had done
much more than simply invent cameras and films; he had invented
a system and then developed the means for supporting that system.
This is essentially what the Eastman Kodak Company continued to
accomplish with the series of Instamatics and other descendants of
the original Brownie. In the decade between 1963 and 1973, for example,
approximately sixty million Instamatics were sold throughout
the world.
The research, manufacturing, and marketing activities of the
Eastman Kodak Company have been so complex and varied that no
one would suggest that the company’s prosperity rests solely on the
success of its line of inexpensive cameras and cartridge films, although
these have continued to be important to the company. Like
Kodak, however, most large companies in the photographic indus-

try have expanded their research to satisfy the ever-growing demand
from amateurs. The amateurism that George Eastman recognized
and encouraged at the beginning of the twentieth century
thus still flourished at its end.
See also Autochrome plate; Color film; Instant photography.
Further Reading
Brownie camera / 137
Brooke-Ball, Peter. George Eastman and Kodak. Watford: Exley, 1994.
Collins, Douglas. The Story of Kodak. New York: Harry N. Abrams,
1990.
Freund, Gisele. Photography and Society. Boston: David R. Godine,
1980.
Wade, John. A Short History of the Camera. Watford, England: Fountain
Press, 1979.
West, Nancy Martha. Kodak and the Lens of Nostalgia. Charlottesville:
University Press of Virginia, 2000.

138
Bubble memory
Bubble memory
The invention: An early nonvolatile medium for storing information
on computers.
The person behind the invention:
Andrew H. Bobeck (1926- ), a Bell Telephone Laboratories
scientist
Magnetic Technology
The fanfare over the commercial prospects of magnetic bubbles
was begun on August 8, 1969, by a report appearing in both The New
York Times and The Wall Street Journal. The early 1970’s would see the
anticipation mount (at least in the computer world) with each prediction
of the benefits of this revolution in information storage technology.
Although it was not disclosed to the public until August of 1969,
magnetic bubble technology had held the interest of a small group
of researchers around the world for many years. The organization
that probably can claim the greatest research advances with respect
to computer applications of magnetic bubbles is Bell Telephone
Laboratories (later part of American Telephone and Telegraph). Basic
research into the properties of certain ferrimagnetic materials
started at Bell Laboratories shortly after the end of World War II
(1939-1945).
Ferrimagnetic substances are typically magnetic iron oxides. Research
into the properties of these and related compounds accelerated
after the discovery of ferrimagnetic garnets in 1956 (these are a
class of ferrimagnetic oxide materials that have the crystal structure
of garnet). Ferrimagnetism is similar to ferromagnetism, the phenomenon
that accounts for the strong attraction of one magnetized
body for another. The ferromagnetic materials most suited for bubble
memories contain, in addition to iron, the element yttrium or a
metal from the rare earth series.
It was a fruitful collaboration between scientist and engineer,
between pure and applied science, that produced this promising

eakthrough in data storage technology. In 1966, Bell Laboratories
scientist Andrew H. Bobeck and his coworkers were the first to realize
the data storage potential offered by the strange behavior of thin
slices of magnetic iron oxides under an applied magnetic field. The
first U.S. patent for a memory device using magnetic bubbles was
filed by Bobeck in the fall of 1966 and issued on August 5, 1969.
Bubbles Full of Memories
Bubble memory / 139
The three basic functional elements of a computer are the central
processing unit, the input/output unit, and memory. Most implementations
of semiconductor memory require a constant power
source to retain the stored data. If the power is turned off, all stored
data are lost. Memory with this characteristic is called “volatile.”
Disks and tapes, which are typically used for secondary memory,
are “nonvolatile.” Nonvolatile memory relies on the orientation of
magnetic domains, rather than on electrical currents, to sustain its
existence.
One can visualize by analogy how this will work by taking a
group of permanent bar magnets that are labeled with N for north at
one end and S for south at the other. If an arrow is painted starting
from the north end with the tip at the south end on each magnet, an
orientation can then be assigned to a magnetic domain (here one
whole bar magnet). Data are “stored” with these bar magnets by arranging
them in rows, some pointing up, some pointing down. Different
arrangements translate to different data. In the binary world
of the computer, all information is represented by two states. A
stored data item (known as a “bit,” or binary digit) is either on or off,
up or down, true or false, depending on the physical representation.
The “on” state is commonly labeled with the number 1 and the “off”
state with the number 0. This is the principle behind magnetic disk
and tape data storage.
Now imagine a thin slice of a certain type of magnetic material in
the shape of a 3-by-5-inch index card. Under a microscope, using a
special source of light, one can see through this thin slice in many regions
of the surface. Darker, snakelike regions can also be seen, representing
domains of an opposite orientation (polarity) to the transparent
regions. If a weak external magnetic field is then applied by

140 / Bubble memory
placing a permanent magnet of the same shape as the card on the
underside of the slice, a strange thing happens to the dark serpentine
pattern—the long domains shrink and eventually contract into
“bubbles,” tiny magnetized spots. Viewed from the side of the slice,
the bubbles are cylindrically shaped domains having a polarity opposite
to that of the material on which they rest. The presence or absence
of a bubble indicates eithera0ora1bit. Data bits are stored by
moving the bubbles in the thin film. As long as the field is applied
by the permanent magnet substrate, the data will be retained. The
bubble is thus a nonvolatile medium for data storage.
Consequences
Magnetic bubble memory created quite a stir in 1969 with its
splashy public introduction. Most of the manufacturers of computer
chips immediately instituted bubble memory development projects.
Texas Instruments, Philips, Hitachi, Motorola, Fujitsu, and International
Business Machines (IBM) joined the race with Bell Laboratories
to mass-produce bubble memory chips. Texas Instruments
became the first major chip manufacturer to mass-produce bubble
memories in the mid-to-late 1970’s. By 1990, however, almost all the
research into magnetic bubble technology had shifted to Japan.
Hitachi and Fujitsu began to invest heavily in this area.
Mass production proved to be the most difficult task. Although
the materials it uses are different, the process of producing magnetic
bubble memory chips is similar to the process applied in producing
semiconductor-based chips such as those used for random access
memory (RAM). It is for this reason that major semiconductor manufacturers
and computer companies initially invested in this technology.
Lower fabrication yields and reliability issues plagued
early production runs, however, and, although these problems
have mostly been solved, gains in the performance characteristics of
competing conventional memories have limited the impact that
magnetic bubble technology has had on the marketplace. The materials
used for magnetic bubble memories are costlier and possess
more complicated structures than those used for semiconductor or
disk memory.
Speed and cost of materials are not the only bases for compari-

son. It is possible to perform some elementary logic with magnetic
bubbles. Conventional semiconductor-based memory offers storage
only. The capability of performing logic with magnetic bubbles
puts bubble technology far ahead of other magnetic technologies
with respect to functional versatility.
A small niche market for bubble memory developed in the 1980’s.
Magnetic bubble memory can be found in intelligent terminals, desktop
computers, embedded systems, test equipment, and similar microcomputer-based
systems.
See also Computer chips; Floppy disk; Hard disk; Optical disk;
Personal computer.
Further Reading
Bubble memory / 141
“Bubble Memory’s Ruggedness Revives Interest for Military Use.”
Aviation Week and Space Technology 130, no. 3 (January 16, 1989).
Graff, Gordon. “Better Bubbles.” Popular Science 232, no. 2 (February,
1988).
McLeod, Jonah. “Will Bubble Memories Make a Comeback?” Electronics
61, no. 14 (August, 1988).
Nields, Megan. “Bubble Memory Bursts into Niche Markets.” Mini-
Micro Systems 20, no. 5 (May, 1987).

142
Bullet train
Bullet train
The invention: An ultrafast passenger railroad system capable of
moving passengers at speeds double or triple those of ordinary
trains.
The people behind the invention:
Ikeda Hayato (1899-1965), Japanese prime minister from 1960 to
1964, who pushed for the expansion of public expenditures
Shinji Sogo (1901-1971), the president of the Japanese National
Railways, the “father of the bullet train”
Building a Faster Train
By 1900, Japan had a world-class railway system, a logical result
of the country’s dense population and the needs of its modernizing
economy. After 1907, the government controlled the system
through the Japanese National Railways (JNR). In 1938, JNR engineers
first suggested the idea of a train that would travel 125 miles
per hour from Tokyo to the southern city of Shimonoseki. Construction
of a rapid train began in 1940 but was soon stopped because of
World War II.
The 311-mile railway between Tokyo and Osaka, the Tokaido
Line, has always been the major line in Japan. By 1957, a business express
along the line operated at an average speed of 57 miles per
hour, but the double-track line was rapidly reaching its transport capacity.
The JNR established two investigative committees to explore
alternative solutions. In 1958, the second committee recommended
the construction of a high-speed railroad on a separate double track,
to be completed in time for the Tokyo Olympics of 1964. The Railway
Technical Institute of the JNR concluded that it was feasible to
design a line that would operate at an average speed of about 130
miles per hour, cutting time for travel between Tokyo and Osaka
from six hours to three hours.
By 1962, about 17 miles of the proposed line were completed for
test purposes. During the next two years, prototype trains were
tested to correct flaws and make improvements in the design. The en-

tire project was completed on schedule in July, 1964, with total construction
costs of more than $1 billion, double the original estimates.
The Speeding Bullet
Bullet train / 143
Service on the Shinkansen, or New Trunk Line, began on October
1, 1964, ten days before the opening of the Olympic Games.
Commonly called the “bullet train” because of its shape and speed,
the Shinkansen was an instant success with the public, both in Japan
and abroad. As promised, the time required to travel between Tokyo
and Osaka was cut in half. Initially, the system provided daily
services of sixty trains consisting of twelve cars each, but the number
of scheduled trains was almost doubled by the end of the year.
The Shinkansen was able to operate at its unprecedented speed
because it was designed and operated as an integrated system,
making use of countless technological and scientific developments.
Tracks followed the standard gauge of 56.5 inches, rather than the
more narrow gauge common in Japan. For extra strength, heavy
Japanese bullet trains. (PhotoDisc)

144 / Bullet train
welded rails were attached directly onto reinforced concrete slabs.
The minimum radius of a curve was 8,200 feet, except where sharper
curves were mandated by topography. In many ways similar to
modern airplanes, the railway cars were made airtight in order to
prevent ear discomfort caused by changes in pressure when trains
enter tunnels.
The Shinkansen trains were powered by electric traction motors,
with four 185-kilowatt motors on each car—one motor attached to
each axle. This design had several advantages: It provided an even
distribution of axle load for reducing strain on the tracks; it allowed
the application of dynamic brakes (where the motor was used for
braking) on all axles; and it prevented the failure of one or two units
from interrupting operation of the entire train. The 25,000-volt electrical
current was carried by trolley wire to the cars, where it was
rectified into a pulsating current to drive the motors.
The Shinkansen system established a casualty-free record because
of its maintenance policies combined with its computerized
Centralized Traffic Control system. The control room at Tokyo Station
was designed to maintain timely information about the location
of all trains and the condition of all routes. Although train operators
had some discretion in determining speed, automatic brakes
also operated to ensure a safe distance between trains. At least once
each month, cars were thoroughly inspected; every ten days, an inspection
train examined the conditions of tracks, communication
equipment, and electrical systems.
Impact
Public usage of the Tokyo-Osaka bullet train increased steadily
because of the system’s high speed, comfort, punctuality, and superb
safety record. Businesspeople were especially happy that the
rapid service allowed them to make the round-trip without the necessity
of an overnight stay, and continuing modernization soon allowed
nonstop trains to make a one-way trip in two and one-half
hours, requiring speeds of 160 miles per hour in some stretches. By
the early 1970’s, the line was transporting a daily average of 339,000
passengers in 240 trains, meaning that a train departed from Tokyo
about every ten minutes.

The popularity of the Shinkansen system quickly resulted in demands
for its extension into other densely populated regions. In
1972, a 100-mile stretch between Osaka and Okayama was opened
for service. By 1975, the line was further extended to Hakata on the
island of Kyushu, passing through the Kammon undersea tunnel.
The cost of this 244-mile stretch was almost $2.5 billion. In 1982,
lines were completed from Tokyo to Niigata and from Tokyo to
Morioka. By 1993, the system had grown to 1,134 miles of track.
Since high usage made the system extremely profitable, the sale of
the JNR to private companies in 1987 did not appear to produce adverse
consequences.
The economic success of the Shinkansen had a revolutionary effect
on thinking about the possibilities of modern rail transportation,
leading one authority to conclude that the line acted as “a
savior of the declining railroad industry.” Several other industrial
countries were stimulated to undertake large-scale railway projects;
France, especially, followed Japan’s example by constructing highspeed
electric railroads from Paris to Nice and to Lyon. By the mid-
1980’s, there were experiments with high-speed trains based on
magnetic levitation and other radical innovations, but it was not
clear whether such designs would be able to compete with the
Shinkansen model.
See also Airplane; Atomic-powered ship; Diesel locomotive; Supersonic
passenger plane.
Further Reading
Bullet train / 145
French, Howard W. “Japan’s New Bullet Train Draws Fire.” New
York Times (September 24, 2000).
Frew, Tim. Locomotives: From the Steam Locomotive to the Bullet Train.
New York: Mallard Press, 1990.
Holley, David. “Faster Than a Speeding Bullet: High-Speed Trains
Are Japan’s Pride, Subject of Debate.” Los Angeles Times (April 10,
1994).
O’Neill, Bill. “Beating the Bullet Train.” New Scientist 140, no. 1893
(October 2, 1993).
Raoul, Jean-Claude. “How High-Speed Trains Make Tracks.” Scientific
American 277 (October, 1997).

146
Buna rubber
Buna rubber
The invention: The first practical synthetic rubber product developed,
Buna inspired the creation of other other synthetic substances
that eventually replaced natural rubber in industrial applications.
The people behind the invention:
Charles de la Condamine (1701-1774), a French naturalist
Charles Goodyear (1800-1860), an American inventor
Joseph Priestley (1733-1804), an English chemist
Charles Greville Williams (1829-1910), an English chemist
A New Synthetic Rubber
The discovery of natural rubber is often credited to the French
scientist Charles de la Condamine, who, in 1736, sent the French
Academy of Science samples of an elastic material used by Peruvian
Indians to make balls that bounced. The material was primarily a
curiosity until 1770, when Joseph Priestley, an English chemist, discovered
that it rubbed out pencil marks, after which he called it
“rubber.” Natural rubber, made from the sap of the rubber tree
(Hevea brasiliensis), became important after Charles Goodyear discovered
in 1830 that heating rubber with sulfur (a process called
“vulcanization”) made it more elastic and easier to use. Vulcanized
natural rubber came to be used to make raincoats, rubber bands,
and motor vehicle tires.
Natural rubber is difficult to obtain (making one tire requires
the amount of rubber produced by one tree in two years), and wars
have often cut off supplies of this material to various countries.
Therefore, efforts to manufacture synthetic rubber began in the
late eighteenth century. Those efforts followed the discovery by
English chemist Charles Greville Williams and others in the 1860’s
that natural rubber was composed of thousands of molecules of a
chemical called isoprene that had been joined to form giant, necklace-like
molecules. The first successful synthetic rubber, Buna,
was patented by Germany’s I. G. Farben Industrie in 1926. The suc-

Buna rubber / 147
cess of this rubber led to the development of many other synthetic
rubbers, which are now used in place of natural rubber in many
applications.
Charles Goodyear
It was an accident that finally showed Charles Goodyear
(1800-1860) how to make rubber into a durable, practical material.
For years he had been experimenting at home looking for
ways to improve natural rubber—and producing stenches that
drove his family and neighbors to distraction—when in 1839 he
dropped a piece of rubber mixed with sulfur onto a hot stove.
When he examined the charred specimen, he discovered it was
not sticky, as hot natural rubber always is, and when he took it
outside into the cold, it did not become brittle.
The son of an inventor, Goodyear invented much
more than his vulcanizing process for rubber. He also
patented a spring-lever faucet, pontoon boat, hay fork,
and air pump, but he was never successful in making
money from his inventions. Owner of a hardware
store, he went broke during a financial panic in 1830
and had to spend time in debtor’s prison. He was
never financially stable afterwards, often having to
borrow money and sell his family’s belongings to
support his experiments. And he had a large family—twelve
children, of whom only half lived beyond childhood.
Even vulcanized rubber did not make Goodyear’s fortune.
He delayed patenting it until Thomas Hancock, an Englishman,
replicated Goodyear’s method of vulcanizing and began producing
rubber in England. Goodyear sued and lost. Others stole
his method, and although he won one large case, legal expenses
took away most of the settlement. He borrowed more and more
money to advertise his product, with some success. For example,
Emperor Napoleon III awarded Goodyear the Cross of the
Legion of Honor for his display at the 1851 Crystal Palace Exhibition
in London. Nevertheless, Goodyear died deeply in debt.
Despite all the imitators, vulcanized rubber remained associated
with Goodyear. Thirty-eight years after he died, the
world’s larger rubber manufacturer took his name for the company’s
title.
(Smithsonian Institution)

148 / Buna rubber
From Erasers to Gas Pumps
Natural rubber belongs to the group of chemicals called “polymers.”
A polymer is a giant molecule that is made up of many simpler
chemical units (“monomers”) that are attached chemically to
form long strings. In natural rubber, the monomer is isoprene
(dimethylbutadiene). The first efforts to make a synthetic rubber
used the discovery that isoprene could be made and converted
into an elastic polymer. The synthetic rubber that was created from
isoprene was, however, inferior to natural rubber. The first Buna
rubber, which was patented by I. G. Farben in 1926, was better, but it
was still less than ideal. Buna rubber was made by polymerizing the
monomer butadiene in the presence of sodium. The name Buna
comes from the first two letters of the words “butadiene” and “natrium”
(German for sodium). Natural and Buna rubbers are called
homopolymers because they contain only one kind of monomer.
The ability of chemists to make Buna rubber, along with its successful
use, led to experimentation with the addition of other monomers
to isoprene-like chemicals used to make synthetic rubber.
Among the first great successes were materials that contained two
alternating monomers; such materials are called “copolymers.” If
the two monomers are designated A and B, part of a polymer molecule
can be represented as (ABABABABABABABABAB). Numerous
synthetic copolymers, which are often called “elastomers,” now
replace natural rubber in applications where they have superior
properties. All elastomers are rubbers, since objects made from
them both stretch greatly when pulled and return quickly to their
original shape when the tension is released.
Two other well-known rubbers developed by I. G. Farben are the
copolymers called Buna-N and Buna-S. These materials combine butadiene
and the monomers acrylonitrile and styrene, respectively.
Many modern motor vehicle tires are made of synthetic rubber that
differs little from Buna-S rubber. This rubber was developed after
the United States was cut off in the 1940’s, during World War II,
from its Asian source of natural rubber. The solution to this problem
was the development of a synthetic rubber industry based on GR-S
rubber (government rubber plus styrene), which was essentially
Buna-S rubber. This rubber is still widely used.

Buna-S rubber is often made by mixing butadiene and styrene in
huge tanks of soapy water, stirring vigorously, and heating the mixture.
The polymer contains equal amounts of butadiene and styrene
(BSBSBSBSBSBSBSBS). When the molecules of the Buna-S polymer
reach the desired size, the polymerization is stopped and the rubber
is coagulated (solidified) chemically. Then, water and all the unused
starting materials are removed, after which the rubber is dried and
shipped to various plants for use in tires and other products. The
major difference between Buna-S and GR-S rubber is that the method
of making GR-S rubber involves the use of low temperatures.
Buna-N rubber is made in a fashion similar to that used for Buna-
S, using butadiene and acrylonitrile. Both Buna-N and the related
neoprene rubber, invented by Du Pont, are very resistant to gasoline
and other liquid vehicle fuels. For this reason, they can be used in
gas-pump hoses. All synthetic rubbers are vulcanized before they
are used in industry.
Impact
Buna rubber / 149
Buna rubber became the basis for the development of the other
modern synthetic rubbers. These rubbers have special properties
that make them suitable for specific applications. One developmental
approach involved the use of chemically modified butadiene in
homopolymers such as neoprene. Made of chloroprene (chlorobutadiene),
neoprene is extremely resistant to sun, air, and chemicals.
It is so widely used in machine parts, shoe soles, and hoses that
more than 400 million pounds are produced annually.
Another developmental approach involved copolymers that alternated
butadiene with other monomers. For example, the successful
Buna-N rubber (butadiene and acrylonitrile) has properties
similar to those of neoprene. It differs sufficiently from neoprene,
however, to be used to make items such as printing press rollers.
About 200 million pounds of Buna-N are produced annually. Some
4 billion pounds of the even more widely used polymer Buna-S/
GR-S are produced annually, most of which is used to make tires.
Several other synthetic rubbers have significant industrial applications,
and efforts to make copolymers for still other purposes continue.

150 / Buna rubber
See also Neoprene; Nylon; Orlon; Plastic; Polyester; Polyethylene;
Polystyrene; Silicones; Teflon; Velcro.
Further Reading
Herbert, Vernon. Synthetic Rubber: A Project That Had to Succeed.
Westport, Conn.: Greenwood Press, 1985.
Mossman, S. T. I., and Peter John Turnbull Morris. The Development of
Plastics. Cambridge: Royal Society of Chemistry, 1994.
Von Hagen, Victor Wolfgang. South America Called Them: Explorations
of the Great Naturalists, La Condamine, Humboldt, Darwin,
Spruce. New York: A. A. Knopf, 1945.

CAD/CAM
CAD/CAM
The invention: Computer-Aided Design (CAD) and Computer-
Aided Manufacturing (CAM) enhanced flexibility in engineering
design, leading to higher quality and reduced time for manufacturing
The people behind the invention:
Patrick Hanratty, a General Motors Research Laboratory
worker who developed graphics programs
Jack St. Clair Kilby (1923- ), a Texas Instruments employee
who first conceived of the idea of the integrated circuit
Robert Noyce (1927-1990), an Intel Corporation employee who
developed an improved process of manufacturing
integrated circuits on microchips
Don Halliday, an early user of CAD/CAM who created the
Made-in-America car in only four months by using CAD
and project management software
Fred Borsini, an early user of CAD/CAM who demonstrated
its power
Summary of Event
151
Computer-Aided Design (CAD) is a technique whereby geometrical
descriptions of two-dimensional (2-D) or three-dimensional (3-
D) objects can be created and stored, in the form of mathematical
models, in a computer system. Points, lines, and curves are represented
as graphical coordinates. When a drawing is requested from
the computer, transformations are performed on the stored data,
and the geometry of a part or a full view from either a two- or a
three-dimensional perspective is shown. CAD systems replace the
tedious process of manual drafting, and computer-aided drawing
and redrawing that can be retrieved when needed has improved
drafting efficiency. A CAD system is a combination of computer
hardware and software that facilitates the construction of geometric
models and, in many cases, their analysis. It allows a wide variety of
visual representations of those models to be displayed.

152 / CAD/CAM
Computer-Aided Manufacturing (CAM) refers to the use of computers
to control, wholly or partly, manufacturing processes. In
practice, the term is most often applied to computer-based developments
of numerical control technology; robots and flexible manufacturing
systems (FMS) are included in the broader use of CAM
systems. A CAD/CAM interface is envisioned as a computerized
database that can be accessed and enriched by either design or manufacturing
professionals during various stages of the product development
and production cycle.
In CAD systems of the early 1990’s, the ability to model solid objects
became widely available. The use of graphic elements such as
lines and arcs and the ability to create a model by adding and subtracting
solids such as cubes and cylinders are the basic principles of
CAD and of simulating objects within a computer. CAD systems enable
computers to simulate both taking things apart (sectioning)
and putting things together for assembly. In addition to being able
to construct prototypes and store images of different models, CAD
systems can be used for simulating the behavior of machines, parts,
and components. These abilities enable CAD to construct models
that can be subjected to nondestructive testing; that is, even before
engineers build a physical prototype, the CAD model can be subjected
to testing and the results can be analyzed. As another example,
designers of printed circuit boards have the ability to test their
circuits on a CAD system by simulating the electrical properties of
components.
During the 1950’s, the U.S. Air Force recognized the need for reducing
the development time for special aircraft equipment. As a
result, the Air Force commissioned the Massachusetts Institute of
Technology to develop numerically controlled (NC) machines that
were programmable. A workable demonstration of NC machines
was made in 1952; this began a new era for manufacturing. As the
speed of an aircraft increased, the cost of manufacturing also increased
because of stricter technical requirements. This higher cost
provided a stimulus for the further development of NC technology,
which promised to reduce errors in design before the prototype
stage.
The early 1960’s saw the development of mainframe computers.
Many industries valued computing technology for its speed and for

CAD/CAM / 153
its accuracy in lengthy and tedious numerical operations in design,
manufacturing, and other business functional areas. Patrick
Hanratty, working for General Motors Research Laboratory, saw
other potential applications and developed graphics programs for
use on mainframe computers. The use of graphics in software aided
the development of CAD/CAM, allowing visual representations of
models to be presented on computer screens and printers.
The 1970’s saw an important development in computer hardware,
namely the development and growth of personal computers
(PCs). Personal computers became smaller as a result of the development
of integrated circuits. Jack St. Clair Kilby, working for Texas
Instruments, first conceived of the integrated circuit; later, Robert
Noyce, working for Intel Corporation, developed an improved process
of manufacturing integrated circuits on microchips. Personal
computers using these microchips offered both speed and accuracy
at costs much lower than those of mainframe computers.
Five companies offered integrated commercial computer-aided
design and computer-aided manufacturing systems by the first half
of 1973. Integration meant that both design and manufacturing
were contained in one system. Of these five companies—Applicon,
Computervision, Gerber Scientific, Manufacturing and Consulting
Services (MCS), and United Computing—four offered turnkey systems
exclusively. Turnkey systems provide design, development,
training, and implementation for each customer (company) based
on the contractual agreement; they are meant to be used as delivered,
with no need for the purchaser to make significant adjustments
or perform programming.
The 1980’s saw a proliferation of mini- and microcomputers with
a variety of platforms (processors) with increased speed and better
graphical resolution. This made the widespread development of
computer-aided design and computer-aided manufacturing possible
and practical. Major corporations spent large research and development
budgets developing CAD/CAM systems that would
automate manual drafting and machine tool movements. Don Halliday,
working for Truesports Inc., provided an early example of the
benefits of CAD/CAM. He created the Made-in-America car in only
four months by using CAD and project management software. In
the late 1980’s, Fred Borsini, the president of Leap Technologies in

154 / CAD/CAM
Michigan, brought various products to market in record time through
the use of CAD/CAM.
In the early 1980’s, much of the CAD/CAM industry consisted of
software companies. The cost for a relatively slow interactive system
in 1980 was close to $100,000. The late 1980’s saw the demise of
minicomputer-based systems in favor of Unix work stations and
PCs based on 386 and 486 microchips produced by Intel. By the time
of the International Manufacturing Technology show in September,
1992, the industry could show numerous CAD/CAM innovations
including tools, CAD/CAM models to evaluate manufacturability
in early design phases, and systems that allowed use of the same
data for a full range of manufacturing functions.
Impact
In 1990, CAD/CAM hardware sales by U.S. vendors reached
$2.68 billion. In software alone, $1.42 billion worth of CAD/CAM
products and systems were sold worldwide by U.S. vendors, according
to International Data Corporation figures for 1990. CAD/
CAM systems were in widespread use throughout the industrial
world. Development lagged in advanced software applications,
particularly in image processing, and in the communications software
and hardware that ties processes together.
A reevaluation of CAD/CAM systems was being driven by the
industry trend toward increased functionality of computer-driven
numerically controlled machines. Numerical control (NC) software
enables users to graphically define the geometry of the parts in a
product, develop paths that machine tools will follow, and exchange
data among machines on the shop floor. In 1991, NC configuration
software represented 86 percent of total CAM sales. In 1992,
the market shares of the five largest companies in the CAD/CAM
market were 29 percent for International Business Machines, 17 percent
for Intergraph, 11 percent for Computervision, 9 percent for
Hewlett-Packard, and 6 percent for Mentor Graphics.
General Motors formed a joint venture with Ford and Chrysler to
develop a common computer language in order to make the next
generation of CAD/CAM systems easier to use. The venture was
aimed particularly at problems that posed barriers to speeding up

CAD/CAM / 155
the design of new automobiles. The three car companies all had sophisticated
computer systems that allowed engineers to design
parts on computers and then electronically transmit specifications
to tools that make parts or dies.
CAD/CAM technology was expected to advance on many fronts.
As of the early 1990’s, different CAD/CAM vendors had developed
systems that were often incompatible with one another, making it
difficult to transfer data from one system to another. Large corporations,
such as the major automakers, developed their own interfaces
and network capabilities to allow different systems to communicate.
Major users of CAD/CAM saw consolidation in the industry
through the establishment of standards as being in their interests.
Resellers of CAD/CAM products also attempted to redefine
their markets. These vendors provide technical support and service
to users. The sale of CAD/CAM products and systems offered substantial
opportunities, since demand remained strong. Resellers
worked most effectively with small and medium-sized companies,
which often were neglected by the primary sellers of CAD/CAM
equipment because they did not generate a large volume of business.
Some projections held that by 1995 half of all CAD/CAM systems
would be sold through resellers, at a cost of $10,000 or less for
each system. The CAD/CAM market thus was in the process of dividing
into two markets: large customers (such as aerospace firms
and automobile manufacturers) that would be served by primary
vendors, and small and medium-sized customers that would be serviced
by resellers.
CAD will find future applications in marketing, the construction
industry, production planning, and large-scale projects such as shipbuilding
and aerospace. Other likely CAD markets include hospitals,
the apparel industry, colleges and universities, food product
manufacturers, and equipment manufacturers. As the linkage between
CAD and CAM is enhanced, systems will become more productive.
The geometrical data from CAD will be put to greater use
by CAM systems.
CAD/CAM already had proved that it could make a big difference
in productivity and quality. Customer orders could be changed
much faster and more accurately than in the past, when a change
could require a manual redrafting of a design. Computers could do

156 / CAD/CAM
automatically in minutes what once took hours manually. CAD/
CAM saved time by reducing, and in some cases eliminating, human
error. Many flexible manufacturing systems (FMS) had machining
centers equipped with sensing probes to check the accuracy
of the machining process. These self-checks can be made part of numerical
control (NC) programs. With the technology of the early
1990’s, some experts estimated that CAD/CAM systems were in
many cases twice as productive as the systems they replaced; in the
long run, productivity is likely to improve even more, perhaps up to
three times that of older systems or even higher. As costs for CAD/
CAM systems concurrently fall, the investment in a system will be
recovered more quickly. Some analysts estimated that by the mid-
1990’s, the recovery time for an average system would be about
three years.
Another frontier in the development of CAD/CAM systems is
expert (or knowledge-based) systems, which combine data with a
human expert’s knowledge, expressed in the form of rules that the
computer follows. Such a system will analyze data in a manner
mimicking intelligence. For example, a 3-D model might be created
from standard 2-D drawings. Expert systems will likely play a
pivotal role in CAM applications. For example, an expert system
could determine the best sequence of machining operations to produce
a component.
Continuing improvements in hardware, especially increased
speed, will benefit CAD/CAM systems. Software developments,
however, may produce greater benefits. Wider use of CAD/CAM
systems will depend on the cost savings from improvements in
hardware and software as well as on the productivity of the systems
and the quality of their product. The construction, apparel,
automobile, and aerospace industries have already experienced
increases in productivity, quality, and profitability through the use
of CAD/CAM. A case in point is Boeing, which used CAD from
start to finish in the design of the 757.
See also Differential analyzer; Mark I calculator; Personal computer;
SAINT; Virtual machine; Virtual reality.

Further Reading
CAD/CAM / 157
Groover, Mikell P., and Emory W. Zimmers, Jr. CAD/CAM: Computer-Aided
Design and Manufacturing. Englewood Cliffs, N.J.:
Prentice-Hall, 1984.
Jurgen, Ronald K. Computers and Manufacturing Productivity. New
York: Institute of Electrical and Electronics Engineers, 1987.
McMahon, Chris, and Jimmie Browne. CAD/CAM: From Principles to
Practice. Reading, Mass.: Addison-Wesley, 1993.
_____. CAD/CAM: Principles, Practice, and Manufacturing Management.
2d ed. Harlow, England: Addison-Wesley, 1998.
Medland, A. J., and Piers Burnett. CAD/CAM in Practice. New York:
John Wiley & Sons, 1986.

158
Carbon dating
Carbon dating
The invention: A technique that measures the radioactive decay of
carbon 14 in organic substances to determine the ages of artifacts
as old as ten thousand years.
The people behind the invention:
Willard Frank Libby (1908-1980), an American chemist who won
the 1960 Nobel Prize in Chemistry
Charles Wesley Ferguson (1922-1986), a scientist who
demonstrated that carbon 14 dates before 1500 b.c. needed to
be corrected
One in a Trillion
Carbon dioxide in the earth’s atmosphere contains a mixture of
three carbon isotopes (isotopes are atoms of the same element that
contain different numbers of neutrons), which occur in the following
percentages: about 99 percent carbon 12, about 1 percent carbon
13, and approximately one atom in a trillion of radioactive carbon
14. Plants absorb carbon dioxide from the atmosphere during photosynthesis,
and then animals eat the plants, so all living plants and
animals contain a small amount of radioactive carbon.
When a plant or animal dies, its radioactivity slowly decreases as
the radioactive carbon 14 decays. The time it takes for half of any radioactive
substance to decay is known as its “half-life.” The half-life
for carbon 14 is known to be about fifty-seven hundred years. The
carbon 14 activity will drop to one-half after one half-life, onefourth
after two half-lives, one-eighth after three half-lives, and so
forth. After ten or twenty half-lives, the activity becomes too low to
be measurable. Coal and oil, which were formed from organic matter
millions of years ago, have long since lost any carbon 14 activity.
Wood samples from an Egyptian tomb or charcoal from a prehistoric
fireplace a few thousand years ago, however, can be dated with
good reliability from the leftover radioactivity.
In the 1940’s, the properties of radioactive elements were still
being discovered and were just beginning to be used to solve problems.
Scientists still did not know the half-life of carbon 14, and ar-

chaeologists still depended mainly on historical evidence to determine
the ages of ancient objects.
In early 1947, Willard Frank Libby started a crucial experiment in
testing for radioactive carbon. He decided to test samples of methane
gas from two different sources. One group of samples came
from the sewage disposal plant at Baltimore, Maryland, which was
rich in fresh organic matter. The other sample of methane came from
an oil refinery, which should have contained only ancient carbon
from fossils whose radioactivity should have completely decayed.
The experimental results confirmed Libby’s suspicions: The methane
from fresh sewage was radioactive, but the methane from oil
was not. Evidently, radioactive carbon was present in fresh organic
material, but it decays away eventually.
Tree-Ring Dating
Carbon dating / 159
In order to establish the validity of radiocarbon dating, Libby analyzed
known samples of varying ages. These included tree-ring
samples from the years 575 and 1075 and one redwood from 979
b.c.e., as well as artifacts from Egyptian tombs going back to about
3000 b.c.e. In 1949, he published an article in the journal Science that
contained a graph comparing the historical ages and the measured
radiocarbon ages of eleven objects. The results were accurate within
10 percent, which meant that the general method was sound.
The first archaeological object analyzed by carbon dating, obtained
from the Metropolitan Museum of Art in New York, was a
piece of cypress wood from the tomb of King Djoser of Egypt. Based
on historical evidence, the age of this piece of wood was about fortysix
hundred years. A small sample of carbon obtained from this
wood was deposited on the inside of Libby’s radiation counter, giving
a count rate that was about 40 percent lower than that of modern
organic carbon. The resulting age of the wood calculated from its residual
radioactivity was about thirty-eight hundred years, a difference
of eight hundred years. Considering that this was the first object
to be analyzed, even such a rough agreement with the historic
age was considered to be encouraging.
The validity of radiocarbon dating depends on an important assumption—namely,
that the abundance of carbon 14 in nature has

160 / Carbon dating
Willard Frank Libby
Born in 1908, Willard Frank Libby came from a family of
farmers in Grand View, Colorado. They moved to Sebastopol,
California, where Libby went through public school. He entered
the University of California, Berkeley, in 1927, earning a
bachelor of science degree in 1931 and a doctorate in 1933. He
stayed on at Berkeley as an instructor of chemistry until he won
the first of his three Guggenheim Fellowships in 1941. He
moved to Princeton University to study, but World War II cut
short his fellowship. Instead, he joined the Manhattan Project,
helping design the atomic bomb at Columbia University’s Division
of War Research.
After the war Libby became a professor of chemistry at the
University of Chicago, where he conducted his research on carbon-14
dating. A leading expert in radiochemistry, he also investigated
isotope tracers and the effects of fallout. However,
his career saw as much public service as research. In 1954 President
Dwight Eisenhower appointed him to the Atomic Energy
Commission as its first chemist, and Libby directed the administration’s
international Atoms for Peace program. He resigned
in 1959 to take an appointment at the University of California,
Los Angeles, as professor of chemistry and then in 1962 as director
of the Institute of Geophysics and Planetary Physics, a
position he held until he died in 1980.
Libby received the Nobel Prize in Chemistry in 1960 for developing
carbon-14 dating. Among his many other honors were
the American Chemical Society’s Willard Gibbs Award in 1958,
the Albert Einstein Medal in 1959, and the Day Medal of the
Geological Society of America in 1961. He was a member of the
Advisory Board of the Guggenheim Memorial Foundation, the
Office of Civil and Defense Mobilization, the National Science
Foundation’s General Commission on Science, and the
Academic Institution and also a director of Douglas Aircraft
Company.
been constant for many thousands of years. If carbon 14 was less
abundant at some point in history, organic samples from that era
would have started with less radioactivity. When analyzed today,
their reduced activity would make them appear to be older than
they really are.

Charles Wesley Ferguson from the Tree-Ring Research Laboratory
at the University of Arizona tackled this problem. He measured
the age of bristlecone pine trees both by counting the rings and by
using carbon 14 methods. He found that carbon 14 dates before
1500 b.c.e. needed to be corrected. The results show that radiocarbon
dates are older than tree-ring counting dates by as much as several
hundred years for the oldest samples. He knew that the number
of tree rings had given him the correct age of the pines, because trees
accumulate one ring of growth for every year of life. Apparently, the
carbon 14 content in the atmosphere has not been constant. Fortunately,
tree-ring counting gives reliable dates that can be used to
correct radiocarbon measurements back to about 6000 b.c.e.
Impact
Carbon dating / 161
Some interesting samples were dated by Libby’s group. The
Dead Sea Scrolls had been found in a cave by an Arab shepherd in
1947, but some Bible scholars at first questioned whether they were
genuine. The linen wrapping from the Book of Isaiah was tested for
carbon 14, giving a date of 100 b.c.e., which helped to establish its
authenticity. Human hair from an Egyptian tomb was determined
to be nearly five thousand years old. Well-preserved sandals from a
cave in eastern Oregon were determined to be ninety-three hundred
years old. A charcoal sample from a prehistoric site in western
South Dakota was found to be about seven thousand years old.
The Shroud of Turin, located in Turin, Italy, has been a controversial
object for many years. It is a linen cloth, more than four meters
long, which shows the image of a man’s body, both front and back.
Some people think it may have been the burial shroud of Jesus
Christ after his crucifixion. A team of scientists in 1978 was permitted
to study the shroud, using infrared photography, analysis of
possible blood stains, microscopic examination of the linen fibers,
and other methods. The results were ambiguous. A carbon 14 test
was not permitted because it would have required cutting a piece
about the size of a handkerchief from the shroud.
A new method of measuring carbon 14 was developed in the late
1980’s. It is called “accelerator mass spectrometry,” or AMS. Unlike
Libby’s method, it does not count the radioactivity of carbon. In-

162 / Carbon dating
stead, a mass spectrometer directly measures the ratio of carbon 14
to ordinary carbon. The main advantage of this method is that the
sample size needed for analysis is about a thousand times smaller
than before. The archbishop of Turin permitted three laboratories
with the appropriate AMS apparatus to test the shroud material.
The results agreed that the material was from the fourteenth century,
not from the time of Christ. The figure on the shroud may be a
watercolor painting on linen.
Since Libby’s pioneering experiments in the late 1940’s, carbon
14 dating has established itself as a reliable dating technique for archaeologists
and cultural historians. Further improvements are expected
to increase precision, to make it possible to use smaller samples,
and to extend the effective time range of the method back to
fifty thousand years or earlier.
See also Atomic clock; Geiger counter; Richter scale.
Further Reading
Goldberg, Paul, Vance T. Holliday, and C. Reid Ferring. Earth Sciences
and Archaeology. New York: Kluwer Academic Plenum, 2001.
Libby, Willard Frank. “Radiocarbon Dating” [Nobel lecture]. In
Chemistry, 1942-1962. River Edge, N.J.: World Scientific, 1999.
Lowe, John J. Radiocarbon Dating: Recent Applications and Future Potential.
New York: John Wiley and Sons, 1996.

Cassette recording
Cassette recording
The invention: Self-contained system making it possible to record
and repeatedly play back sound without having to thread tape
through a machine.
The person behind the invention:
Fritz Pfleumer, a German engineer whose work on audiotapes
paved the way for audiocassette production
Smaller Is Better
163
The introduction of magnetic audio recording tape in 1929 was
met with great enthusiasm, particularly in the entertainment industry,
and specifically among radio broadcasters. Although somewhat
practical methods for recording and storing sound for later playback
had been around for some time, audiotape was much easier to
use, store, and edit, and much less expensive to produce.
It was Fritz Pfleumer, a German engineer, who in 1929 filed the
first audiotape patent. His detailed specifications indicated that
tape could be made by bonding a thin coating of oxide to strips of either
paper or film. Pfleumer also suggested that audiotape could be
attached to filmstrips to provide higher-quality sound than was
available with the film sound technologies in use at that time. In
1935, the German electronics firm AEG produced a reliable prototype
of a record-playback machine based on Pfleumer’s idea. By
1947, the American company 3M had refined the concept to the
point where it was able to produce a high-quality tape using a plastic-based
backing and red oxide. The tape recorded and reproduced
sound with a high degree of clarity and dynamic range and would
soon become the standard in the industry.
Still, the tape was sold and used in a somewhat inconvenient
open-reel format. The user had to thread it through a machine and
onto a take-up reel. This process was somewhat cumbersome and
complicated for the layperson. For many years, sound-recording
technology remained a tool mostly for professionals.
In 1963, the first audiocassette was introduced by the Nether-

164 / Cassette recording
lands-based Philips NV company. This device could be inserted into
a machine without threading. Rewind and fast-forward were faster,
and it made no difference where the tape was stopped prior to the
ejection of the cassette. By contrast, open-reel audiotape required
that the tape be wound fully onto one or the other of the two reels
before it could be taken off the machine.
Technical advances allowed the cassette tape to be much narrower
than the tape used in open reels and also allowed the tape
speed to be reduced without sacrificing sound quality. Thus, the
cassette was easier to carry around, and more sound could be recorded
on a cassette tape. In addition, the enclosed cassette decreased
wear and tear on the tape and protected it from contamination.
Creating a Market
One of the most popular uses for audiocassettes was to record
music from radios and other audio sources for later playback. During
the 1970’s, many radio stations developed “all music” formats
in which entire albums were often played without interruption.
That gave listeners an opportunity to record the music for later
playback. At first, the music recording industry complained about
this practice, charging that unauthorized recording of music from
the radio was a violation of copyright laws. Eventually, the issue
died down as the same companies began to recognize this new, untapped
market for recorded music on cassette.
Audiocassettes, all based on the original Philips design, were being
manufactured by more than sixty companies within only a few
years of their introduction. In addition, spin-offs of that design were
being used in many specialized applications, including dictation,
storage of computer information, and surveillance. The emergence
of videotape resulted in a number of formats for recording and
playing back video based on the same principle. Although each is
characterized by different widths of tape, each uses the same technique
for tape storage and transport.
The cassette has remained a popular means of storing and retrieving
information on magnetic tape for more than a quarter of a
century. During the early 1990’s, digital technologies such as audio
CDs (compact discs) and the more advanced CD-ROM (compact

discs that reproduce sound, text, and images via computer) were beginning
to store information in revolutionary new ways. With the
development of this increasingly sophisticated technology, need for
the audiocassette, once the most versatile, reliable, portable, and
economical means of recording, storing, and playing-back sound,
became more limited.
Consequences
Cassette recording / 165
The cassette represented a new level of convenience for the audiophile,
resulting in a significant increase in the use of recording
technology in all walks of life. Even small children could operate
cassette recorders and players, which led to their use in schools for a
variety of instructional tasks and in the home for entertainment. The
recording industry realized that audiotape cassettes would allow
consumers to listen to recorded music in places where record players
were impractical: in automobiles, at the beach, even while camping.
The industry also saw the need for widespread availability of
music and information on cassette tape. It soon began distributing
albums on audiocassette in addition to the long-play vinyl discs,
and recording sales increased substantially. This new technology
put recorded music into automobiles for the first time, again resulting
in a surge in sales for recorded music. Eventually, information,
including language instruction and books-on-tape, became popular
commuter fare.
With the invention of the microchip, audiotape players became
available in smaller and smaller sizes, making them truly portable.
Audiocassettes underwent another explosion in popularity during
the early 1980’s, when the Sony Corporation introduced the
Walkman, an extremely compact, almost weightless cassette player
that could be attached to clothing and used with lightweight earphones
virtually anywhere. At the same time, cassettes were suddenly
being used with microcomputers for backing up magnetic
data files.
Home video soon exploded onto the scene, bringing with it new
applications for cassettes. As had happened with audiotape, video
camera-recorder units, called “camcorders,” were miniaturized to
the point where 8-millimeter videocassettes capable of recording up

166 / Cassette recording
to 90 minutes of live action and sound were widely available. These
cassettes closely resembled the audiocassette first introduced in
1963.
See also Compact disc; Dolby noise reduction; Electronic synthesizer;
FM radio; Transistor radio; Walkman cassette player.
Further Reading
Miller, Christopher. “The One Hundred Greatest Inventions: Audio
and Video.” Popular Science 254, no. 4 (April, 1999).
Praag, Phil van. Evolution of the Audio Recorder. Waukesha, Wis.: EC
Designs, 1997.
Stark, Craig. “Thirty Five Years of Tape Recording.” Stereo Review 58
(September, 1993).

CAT scanner
CAT scanner
The invention: A technique that collects X-ray data from solid,
opaque masses such as human bodies and uses a computer to
construct a three-dimensional image.
The people behind the invention:
Godfrey Newbold Hounsfield (1919- ), an English
electronics engineer who shared the 1979 Nobel Prize in
Physiology or Medicine
Allan M. Cormack (1924-1998), a South African-born American
physicist who shared the 1979 Nobel Prize in Physiology or
Medicine
James Ambrose, an English radiologist
A Significant Merger
167
Computerized axial tomography (CAT) is a technique that collects
X-ray data from an opaque, solid mass such as a human body
and uses a sophisticated computer to assemble those data into a
three-dimensional image. This sophisticated merger of separate
technologies led to another name for CAT, computer-assisted tomography
(it came to be called computed tomography, or CT). CAT
is a technique of medical radiology, an area of medicine that began
after the German physicist Wilhelm Conrad Röntgen’s 1895 discovery
of the high-energy electromagnetic radiations he named “X
rays.” Röntgen and others soon produced X-ray images of parts of
the human body, and physicians were quick to learn that these images
were valuable diagnostic aids.
In the late 1950’s and early 1960’s, Allan M. Cormack, a physicist
at Tufts University in Massachusetts, pioneered a mathematical
method for obtaining detailed X-ray absorption patterns in opaque
samples meant to model biological samples. His studies used narrow
X-ray beams that were passed through samples at many different angles.
Because the technique probed test samples from many different
points of reference, it became possible—by using the proper mathematics—to
reconstruct the interior structure of a thin slice of the object
being studied.

168 / CAT scanner
Cormack published his data but received almost no recognition
because computers that could analyze the data in an effective fashion
had not yet been developed. Nevertheless, X-ray tomography—
the process of using X-rays to produce detailed images of thin
sections of solid objects—had been born. It remained for Godfrey
Newbold Hounsfield of England’s Electrical and Musical Instruments
(EMI) Limited (independently, and reportedly with no
knowledge of Cormack’s work) to design the first practical CAT
scanner.
A Series of Thin Slices
Hounsfield, like Cormack, realized that X-ray tomography was
the most practical approach to developing a medical body imager. It
could be used to divide any three-dimensional object into a series of
thin slices that could be reconstructed into images by using appropriate
computers. Hounsfield developed another mathematical approach
to the method. He estimated that the technique would make
possible the very accurate reconstruction of images of thin body sections
with a sensitivity well above that of the X-ray methodology
then in use. Moreover, he proposed that his method would enable
Medical technicians studying CAT scan results. (PhotoDisc)

Godfrey Newbold Hounsfield
CAT scanner / 169
On his family farm outside Newark, Nottinghamshire, England,
Godfrey Newbold Hounsfield (born 1919), the youngest
of five children, was usually left to his own devices. The farm,
he later wrote, offered an infinite variety of diversions, and his
favorites were the many mechanical and electrical gadgets. By
his teen years, he was making his own gadgets, such as an electrical
recording machine, and experimenting with homemade
gliders and water-propelled rockets. All these childhood projects
taught him the fundamentals of practical reasoning.
During World War II he joined the Royal Air Force, where
his talent with gadgets got him a position as an instructor at the
school for radio mechanics. There, on his own, he built his an oscilloscope
and demonstration equipment. This initiative caught
the eye of a high-ranking officer, who after the war arranged a
scholarship so that Hounsfield could attend the Faraday Electrical
Engineering College in London. Upon graduating in 1951,
he took a research position with Electrical and Musical Instruments,
Limited (EMI). His first assignments involved radar and
guided weapons, but he also developed an interest in computers
and in 1958 led the design team that put together England’s
first all-transistor computer, the EMIDEC 1100. This experience,
in turn, prepared him to follow through on his idea for computed
tomography, which came to him in 1967.
EMI released its first CT scanner in 1971, and it so impressed
the medical world that in 1979 Hounsfield and Allan M. Cormack
shared the Nobel Prize in Physiology or Medicine for the
invention. Hounsfield, who continued to work on improved
computed tomography and other diagnostic imagining techniques,
was knighted in 1981.
researchers and physicians to distinguish between normal and diseased
tissue. Hounsfield was correct about that.
The prototype instrument that Hounsfield developed was quite
slow, requiring nine days to scan an object. Soon, he modified the
scanner so that its use took only nine hours, and he obtained successful
tomograms of preserved human brains and the fresh brains
of cattle. The further development of the CAT scanner then pro-

170 / CAT scanner
ceeded quickly, yielding an instrument that required four and onehalf
minutes to gather tomographic data and twenty minutes to
produce the tomographic image.
In late 1971, the first clinical CAT scanner was installed at Atkinson
Morley’s Hospital in Wimbledon, England. By early 1972,
the first patient, a woman with a suspected brain tumor, had been
examined, and the resultant tomogram identified a dark, circular
cyst in her brain. Additional data collection from other patients
soon validated the technique. Hounsfield and EMI patented the
CAT scanner in 1972, and the findings were reported at that year’s
annual meeting of the British Institute of Radiology.
Hounsfield published a detailed description of the instrument in
1973. Hounsfield’s clinical collaborator, James Ambrose, published
on the clinical aspects of the technique. Neurologists all around the
world were ecstatic about the new tool that allowed them to locate
tissue abnormalities with great precision.
The CAT scanner consisted of an X-ray generator, a scanner unit
composed of an X-ray tube and a detector in a circular chamber
about which they could be rotated, a computer that could process
all the data obtained, and a cathode-ray tube on which tomograms
were viewed. To produce tomograms, the patient was placed on a
couch, head inside the scanner chamber, and the emitter-detector
was rotated 1 degree at a time. At each position, 160 readings were
taken, converted to electrical signals, and fed into the computer. In
the 180 degrees traversed, 28,800 readings were taken and processed.
The computer then converted the data into a tomogram (a
cross-sectional representation of the brain that shows the differences
in tissue density). A Polaroid picture of the tomogram was
then taken and interpreted by the physician in charge.
Consequences
Many neurologists agree that CAT is the most important method
developed in the twentieth century to facilitate diagnosis of disorders
of the brain. Even the first scanners could distinguish between
brain tumors and blood clots and help physicians to diagnose a variety
of brain-related birth defects. In addition, the scanners are believed
to have saved many lives by allowing physicians to avoid

the dangerous exploratory brain surgery once required in many
cases and by replacing more dangerous techniques, such as pneumoencephalography,
which required a physician to puncture the
head for diagnostic purposes.
By 1975, improvements, including quicker reaction time and
more complex emitter-detector systems, made it possible for EMI to
introduce full-body CAT scanners to the world market. Then it became
possible to examine other parts of the body—including the
lungs, the heart, and the abdominal organs—for cardiovascular
problems, tumors, and other structural health disorders. The technique
became so ubiquitous that many departments of radiology
changed their names to departments of medical imaging.
The use of CAT scanners has not been problem-free. Part of
the reason for this is the high cost of the devices—ranging from
about $300,000 for early models to $1 million for modern instruments—and
resultant claims by consumer advocacy groups that
the scanners are unnecessarily expensive toys for physicians.
Still, CAT scanners have become important everyday diagnostic
tools in many areas of medicine. Furthermore, continuation of the
efforts of Hounsfield and others has led to more improvements of
CAT scanners and to the use of nonradiologic nuclear magnetic resonance
imaging in such diagnoses.
See also Amniocentesis; Electrocardiogram; Electroencephalogram;
Mammography; Nuclear magnetic resonance; Pap test; Ultrasound;
X-ray image intensifier.
Further Reading
CAT scanner / 171
Gambarelli, J. Computerized Axial Tomography: An Anatomic Atlas of
Serial Sections of the Human Body: Anatomy—Radiology—Scanner.
New York: Springer Verlag, 1977.
Raju, Tones N. K. “The Nobel Chronicles.” Lancet 354, no. 9190 (November
6, 1999).
Thomas, Robert McG., Jr. “Allan Cormack, Seventy Four, Nobelist
Who Helped Invent CAT Scan.” New York Times (May 9, 1998).

172
Cell phone
Cell phone
The invention: Mobile telephone system controlled by computers
to use a region’s radio frequencies, or channels, repeatedly,
thereby accommodating large numbers of users.
The people behind the invention:
William Oliver Baker (1915- ), the president of Bell
Laboratories
Richard H. Fefrenkiel, the head of the mobile systems
engineering department at Bell
The First Radio Telephones
The first recorded attempt to use radio technology to provide direct
access to a telephone system took place in 1920. It was not until
1946, however, that Bell Telephone established the first such commercial
system in St. Louis. The system had a number of disadvantages;
users had to contact an operator who did the dialing and the
connecting, and the use of a single radio frequency prevented simultaneous
talking and listening. In 1949, a system was developed
that used two radio frequencies (a “duplex pair”), permitting both
the mobile unit and the base station to transmit and receive simultaneously
and making a more normal sort of telephone conversation
possible. This type of service, known as Mobile Telephone Service
(MTS), was the norm in the field for many years.
The history of MTS is one of continuously increasing business usage.
The development of the transistor made possible the design and
manufacture of reasonably light, compact, and reliable equipment,
but the expansion of MTS was slowed by the limited number of radio
frequencies; there is nowhere near enough space on the radio spectrum
for each user to have a separate frequency. In New York City, for
example, New York Telephone Company was limited to just twelve
channels for its more than seven hundred mobile subscribers, meaning
that only twelve conversations could be carried on at once. In addition,
because of possible interference, none of those channels could
be reused in nearby cities; only fifty-four channels were available na-

A dominant trend in cell phone design is smaller
and lighter units. (PhotoDisc)
tionwide. By the late 1970’s,
most of the systems in major
cities were considered full, and
new subscribers were placed
on a waiting list; some people
had been waiting for as long
as ten years to become subscribers.
Mobile phone users
commonly experienced long
delays in getting poor-quality
channels.
The Cellular
Breakthrough
Cell phone / 173
In 1968, the Federal Communications
Commission (FCC)
requested proposals for the
creation of high-capacity, spectrum-efficient
mobile systems.
Bell Telephone had already
been lobbying for the creation
of such a system for some years. In the early 1970’s, both Motorola and
Bell Telephone proposed the use of cellular technology to solve the
problems posed by mobile telephone service. Cellular systems involve
the use of a computer to make it possible to use an area’s frequencies,
or channels, repeatedly, allowing such systems to accommodate many
more users.
A two-thousand-customer, 2100-square-mile cellular telephone
system called the Advanced Mobile Phone Service, built by the
AMPS Corporation, an AT&T subsidiary, became operational in
Chicago in 1978. The Illinois Bell Telephone Company was allowed
to make a limited commercial offering and obtained about fourteen
hundred subscribers. American Radio Telephone Service was allowed
to conduct a similar test in the Baltimore/Washington area.
These first systems showed the technological feasibility and affordability
of cellular service.
In 1979, Bell Labs of Murray Hill, New Jersey, received a patent

174 / Cell phone
William Oliver Baker
For great discoveries and inventions to be possible in the
world of high technology, inventors need great facilities—laboratories
and workshops—with brilliant colleagues. These must
be managed by imaginative administrators.
One of the best was William Oliver Baker (b. 1915), who rose
to become president of the legendary Bell Labs. Baker started out
as one of the most promising scientists of his generation. After
earning a Ph.D. in chemistry at Princeton University, he joined
the research section at Bell Telephone Laboratories in 1939. He
studied the physics and chemistry of polymers, especially for use
in electronics and telecommunications. During his research career
he helped develop synthetic rubber and radar, found uses
for polymers in communications and power cables, and participated
in the discovery of microgels. In 1954 he ranked among the
top-ten scientists in American industry and asked to chair a National
Research Council committee studying heat shields for
missiles and satellites.
Administration suited him. The following year he took over
as leader of research at Bell Labs and served as president from
1973 until 1979. Under his direction, basic discoveries and inventions
poured out of the lab that later transformed the way
people live and work: satellite communications, principles for
programming high-speed computers, the technology for modern
electronic communications, the superconducting solenoid,
the maser, and the laser. His scientists won Nobel Prizes and legions
of other honors, as did Baker himself, who received dozens
of medals, awards, and honorary degrees. Moreover, he
was an original member of the President’s Science Advisory
Board, became the first chair of the National Science Information
Council, and served on the National Science Board. His
influence on American science and technology was deep and
lasting.
for such a system. The inventor was Richard H. Fefrenkiel, head of
the mobile systems engineering department under the leadership
of Labs president William Baker. The patented method divides a
city into small coverage areas called “cells,” each served by lowpower
transmitter-receivers. When a vehicle leaves the coverage

of one cell, calls are switched to the antenna and channels of an adjacent
cell; a conversation underway is automatically transferred
and continues without interruption. A channel used in one cell can
be reused a few cells away for a different conversation. In this way,
a few hundred channels can serve hundreds of thousands of users.
Computers control the call-transfer process, effectively reducing
the amount of radio spectrum required. Cellular systems thus actually
use radio frequencies to transmit conversations, but because
the equipment is so telephone-like, “cellular telephone” (or “cell
phone”) became the accepted term for the new technology.
Each AMPS cell station is connected by wire to a central switching
office, which determines when a mobile phone should be transferred
to another cell as the transmitter moves out of range during a
conversation. It does this by monitoring the strength of signals received
from the mobile unit by adjacent cells, “handing off” the call
when a new cell receives a stronger signal; this change is imperceptible
to the user.
Impact
Cell phone / 175
In 1982, the FCC began accepting applications for cellular system
licenses in the thirty largest U.S. cities. By the end of 1984, there
were about forty thousand cellular customers in nearly two dozen
cities. Cellular telephone ownership boomed to 9 million by 1992.
As cellular telephones became more common, they also became
cheaper and more convenient to buy and to use. New systems
developed in the 1990’s continued to make smaller, lighter, and
cheaper cellular phones even more accessible. Since the cellular telephone
was made possible by the marriage of communications and
computers, advances in both these fields have continued to change
the industry at a rapid rate.
Cellular phones have proven ideal for many people who need or
want to keep in touch with others at all times. They also provide
convenient emergency communication devices for travelers and
field-workers. On the other hand, ownership of a cellular phone can
also have its drawbacks; many users have found that they can never
be out of touch—even when they would rather be.

176 / Cell phone
See also Internet; Long-distance telephone; Rotary dial telephone;
Telephone switching; Touch-tone telephone.
Further Reading
Carlo, George Louis, and Martin Schram. Cell Phones: Invisible Hazards
in the Wireless Age. New York: Carroll and Graf, 2001.
“The Cellular Phone.” Newsweek 130, 24A (Winter 1997/1998).
Oliphant, Malcolm W. “How Mobile Telephony Got Going.” IEEE
Spectrum 36, no. 8 (August, 1999).
Young, Peter. Person to Person: The International Impact of the Telephone.
Cambridge: Granta Editions, 1991.

Cloning
Cloning
The invention: Experimental technique for creating exact duplicates
of living organisms by recreating their DNA.
The people behind the invention:
Ian Wilmut, an embryologist with the Roslin Institute
Keith H. S. Campbell, an experiment supervisor with the Roslin
Institute
J. McWhir, a researcher with the Roslin Institute
W. A. Ritchie, a researcher with the Roslin Institute
Making Copies
177
On February 22, 1997, officials of the Roslin Institute, a biological
research institution near Edinburgh, Scotland, held a press conference
to announce startling news: They had succeeded in creating
a clone—a biologically identical copy—from cells taken from
an adult sheep. Although cloning had been performed previously
with simpler organisms, the Roslin Institute experiment marked
the first time that a large, complex mammal had been successfully
cloned.
Cloning, or the production of genetically identical individuals,
has long been a staple of science fiction and other popular literature.
Clones do exist naturally, as in the example of identical twins. Scientists
have long understood the process by which identical twins
are created, and agricultural researchers have often dreamed of a
method by which cheap identical copies of superior livestock could
be created.
The discovery of the double helix structure of deoxyribonucleic
acid (DNA), or the genetic code, by James Watson and Francis Crick
in the 1950’s led to extensive research into cloning and genetic engineering.
Using the discoveries of Watson and Crick, scientists were
soon able to develop techniques to clone laboratory mice; however,
the cloning of complex, valuable animals such as livestock proved
to be hard going.
Early versions of livestock cloning were technical attempts at dupli-

178 / Cloning
Ian Wilmut
Ian Wilmut was born in Hampton Lucey, not far from Warwick
in central England, in 1944. He found his life’s calling in embryology—and
especially animal genetic engineering— while he
was studying at the University of Nottingham, where his mentor
was G. Eric Lamming, a leading expert on reproduction. After
receiving his undergraduate degree, he attended Darwin
College, Cambridge University. He completed his doctorate in
1973 upon submitting a thesis about freezing boar sperm. This
came after he produced a viable calf, named Frosty, from the
frozen semen, the first time anyone had done so.
Soon afterward he joined the Animal Breeding Research Station,
which later became the Roslin Institute in Roslin, Scotland.
He immersed himself in research, seldom working fewer than
nine hours a day. During the 1980’s he experimented with the
insertion of genes into sheep embryos but concluded that cloning
would be less time-consuming and less prone to failure.
Joined by Keith Campbell in 1990, he cloned two Welsh mountain
sheep from differentiated embryo cells, a feat similar to
those of other reproductive experimenters. However, Dolly,
who was cloned from adult cells, shook the world when her
birth was announced in 1997. That same year Wilmut and
Campbell produced another cloned sheep, Polly. Cloned from
fetal skin cells, she was genetically altered to carry a human
gene.
Wilmut’s technique for cloning from adult cells, which the
laboratory patented, was a fundamentally new method of reproduction,
but he had a loftier purpose in mind than simply
establishing a first. He believed that animals genetically engineered
to include human genes can produce proteins needed by
people who because of genetic diseases cannot make the proteins
themselves. The production of new treatments for old diseases,
he told an astonished public after the revelation of Dolly,
was his goal.
cating the natural process of fertilized egg splitting that leads to the
birth of identical twins. Artificially inseminated eggs were removed,
split, and then reinserted into surrogate mothers. This method proved
to be overly costly for commercial purposes, a situation aggravated by
a low success rate.

Nuclear Transfer
Model of a double helix. (PhotoDisc)
Cloning / 179
Researchers at the Roslin Institute found these earlier attempts to
be fundamentally flawed. Even if the success rate could be improved,
the number of clones created (of sheep, in this case) would
still be limited. The Scots, led by embryologist Ian Wilmut and experiment
supervisor Keith Campbell, decided to take an entirely
different approach. The result was the first live birth of a mammal
produced through a process known as “nuclear transfer.”
Nuclear transfer involves the replacement of the nucleus of an
immature egg with a nucleus taken from another cell. Previous attempts
at nuclear transfer had cells from a single embryo divided
up and implanted into an egg. Because a sheep embryo has only
about forty usable cells, this method also proved limiting.
The Roslin team therefore decided to grow their own cells in a
laboratory culture. They took more mature embryonic cells than
those previously used, and they experimented with the use of a nutrient
mixture. One of their breakthroughs occurred when they discovered
that these “cell lines” grew much more quickly when certain
nutrients were absent.

180 / Cloning
Using this technique, the Scots were able to produce a theoretically
unlimited number of genetically identical cell lines. The next
step was to transfer the cell lines of the sheep into the nucleus of unfertilized
sheep eggs.
First, 277 nuclei with a full set of chromosomes were transferred
to the unfertilized eggs. An electric shock was then used to cause the
eggs to begin development, the shock performing the duty of fertilization.
Of these eggs, twenty-nine developed enough to be inserted
into surrogate mothers.
All the embryos died before birth except one: a ewe the scientists
named “Dolly.” Her birth on July 5, 1996, was witnessed by only a
veterinarian and a few researchers. Not until the clone had survived
the critical earliest stages of life was the success of the experiment
disclosed; Dolly was more than seven months old by the time her
birth was announced to a startled world.
Impact
The news that the cloning of sophisticated organisms had left the
realm of science fiction and become a matter of accomplished scientific
fact set off an immediate uproar. Ethicists and media commentators
quickly began to debate the moral consequences of the use—
and potential misuse—of the technology. Politicians in numerous
countries responded to the news by calling for legal restrictions on
cloning research. Scientists, meanwhile, speculated about the possible
benefits and practical limitations of the process.
The issue that stirred the imagination of the broader public and
sparked the most spirited debate was the possibility that similar experiments
might soon be performed using human embryos. Although
most commentators seemed to agree that such efforts would
be profoundly immoral, many experts observed that they would be
virtually impossible to prevent. “Could someone do this tomorrow
morning on a human embryo?” Arthur L. Caplan, the director of the
University of Pennsylvania’s bioethics center, asked reporters. “Yes.
It would not even take too much science. The embryos are out
there.”
Such observations conjured visions of a future that seemed marvelous
to some, nightmarish to others. Optimists suggested that the

est and brightest of humanity could be forever perpetuated, creating
an endless supply of Albert Einsteins and Wolfgang Amadeus
Mozarts. Pessimists warned of a world overrun by clones of selfserving
narcissists and petty despots, or of the creation of a secondary
class of humans to serve as organ donors for their progenitors.
The Roslin Institute’s researchers steadfastly proclaimed their
own opposition to human experimentation. Moreover, most scientists
were quick to point out that such scenarios were far from realization,
noting the extremely high failure rate involved in the creation
of even a single sheep. In addition, most experts emphasized
more practical possible uses of the technology: improving agricultural
stock by cloning productive and disease-resistant animals, for
example, or regenerating endangered or even extinct species. Even
such apparently benign schemes had their detractors, however, as
other observers remarked on the potential dangers of thus narrowing
a species’ genetic pool.
Even prior to the Roslin Institute’s announcement, most European
nations had adopted a bioethics code that flatly prohibited genetic
experiments on human subjects. Ten days after the announcement,
U.S. president Bill Clinton issued an executive order that
banned the use of federal money for human cloning research, and
he called on researchers in the private sector to refrain from such experiments
voluntarily. Nevertheless, few observers doubted that
Dolly’s birth marked only the beginning of an intriguing—and possibly
frightening—new chapter in the history of science.
See also Amniocentesis; Artificial chromosome; Artificial insemination;
Genetic “fingerprinting”; In vitro plant culture; Rice and
wheat strains.
Further Reading
Cloning / 181
Facklam, Margery, Howard Facklam, and Paul Facklam. From Cell to
Clone: The Story of Genetic Engineering. New York: Harcourt Brace
Jovanovich, 1979.
Gillis, Justin. “Cloned Cows Are Fetching Big Bucks: Dozens of Genetic
Duplicates Ready to Take Up Residence on U.S. Farms.”
Washington Post (March 25, 2001).

182 / Cloning
Kolata, Gina Bari. Clone: The Road to Dolly, and the Path Ahead. New
York: William Morrow, 1998.
Regalado, Antonio. “Clues Are Sought for Cloning’s Fail Rate: Researchers
Want to Know Exactly How an Egg Reprograms Adult
DNA.” Wall Street Journal (November 24, 2000).
Winslow, Ron. “Scientists Clone Pigs, Lifting Prospects of Replacement
Organs for Humans.” Wall Street Journal (August 17, 2000).

Cloud seeding
Cloud seeding
The invention: Technique for inducing rainfall by distributing dry
ice or silver nitrate into reluctant rainclouds.
The people behind the invention:
Vincent Joseph Schaefer (1906-1993), an American chemist and
meteorologist
Irving Langmuir (1881-1957), an American physicist and
chemist who won the 1932 Nobel Prize in Chemistry
Bernard Vonnegut (1914-1997), an American physical chemist
and meteorologist
Praying for Rain
183
Beginning in 1943, an intense interest in the study of clouds developed
into the practice of weather “modification.” Working for
the General Electric Research Laboratory, Nobel laureate Irving
Langmuir and his assistant researcher and technician, Vincent Joseph
Schaefer, began an intensive study of precipitation and its
causes.
Past research and study had indicated two possible ways that
clouds produce rain. The first possibility is called “coalescing,” a
process by which tiny droplets of water vapor in a cloud merge after
bumping into one another and become heavier and fatter until they
drop to earth. The second possibility is the “Bergeron process” of
droplet growth, named after the Swedish meteorologist Tor Bergeron.
Bergeron’s process relates to supercooled clouds, or clouds
that are at or below freezing temperatures and yet still contain both
ice crystals and liquid water droplets. The size of the water droplets
allows the droplets to remain liquid despite freezing temperatures;
while small droplets can remain liquid only down to 4 degrees Celsius,
larger droplets may not freeze until reaching −15 degrees
Celsius. Precipitation occurs when the ice crystals become heavy
enough to fall. If the temperature at some point below the cloud is
warm enough, it will melt the ice crystals before they reach the
earth, producing rain. If the temperature remains at the freezing

184 / Cloud seeding
point, the ice crystals retain their form and fall as snow.
Schaefer used a deep-freezing unit in order to observe water
droplets in pure cloud form. In order to observe the droplets better,
Schaefer lined the chest with black velvet and concentrated a beam
of light inside. The first agent he introduced inside the supercooled
freezer was his own breath. When that failed to form the desired ice
crystals, he proceeded to try other agents. His hope was to form ice
crystals that would then cause the moisture in the surrounding air
to condense into more ice crystals, which would produce a miniature
snowfall.
He eventually achieved success when he tossed a handful of dry
ice inside and was rewarded with the long-awaited snow. The
freezer was set at the freezing point of water, 0 degrees Celsius, but
not all the particles were ice crystals, so when the dry ice was introduced
all the stray water droplets froze instantly, producing ice
crystals, or snowflakes.
Planting the First Seeds
On November 13, 1946, Schaefer took to the air over Mount
Greylock with several pounds of dry ice in order to repeat the experiment
in nature. After he had finished sprinkling, or seeding, a
supercooled cloud, he instructed the pilot to fly underneath the
cloud he had just seeded. Schaefer was greeted by the sight of snow.
By the time it reached the ground, it had melted into the first-ever
human-made rainfall.
Independently of Schaefer and Langmuir, another General Electric
scientist, Bernard Vonnegut, was also seeking a way to cause
rain. He found that silver iodide crystals, which have the same size
and shape as ice crystals, could “fool” water droplets into condensing
on them. When a certain chemical mixture containing silver iodide
is heated on a special burner called a “generator,” silver iodide
crystals appear in the smoke of the mixture. Vonnegut’s discovery
allowed seeding to occur in a way very different from seeding with
dry ice, but with the same result. Using Vonnegut’s process, the
seeding is done from the ground. The generators are placed outside
and the chemicals are mixed. As the smoke wafts upward, it carries
the newly formed silver iodide crystals with it into the clouds.

The results of the scientific experiments by Langmuir, Vonnegut,
and Schaefer were alternately hailed and rejected as legitimate.
Critics argue that the process of seeding is too complex and
would have to require more than just the addition of dry ice or silver
nitrate in order to produce rain. One of the major problems surrounding
the question of weather modification by cloud seeding is
the scarcity of knowledge about the earth’s atmosphere. A journey
begun about fifty years ago is still a long way from being completed.
Impact
Although the actual statistical and other proofs needed to support
cloud seeding are lacking, the discovery in 1946 by the General
Electric employees set off a wave of interest and demand for information
that far surpassed the interest generated by the discovery of
nuclear fission shortly before. The possibility of ending drought
and, in the process, hunger excited many people. The discovery also
prompted both legitimate and false “rainmakers” who used the information
gathered by Schaefer, Langmuir, and Vonnegut to set up
cloud-seeding businesses. Weather modification, in its current stage
of development, cannot be used to end worldwide drought. It does,
however, have beneficial results in some cases on the crops of
smaller farms that have been affected by drought.
In order to understand the advances made in weather modification,
new instruments are needed to record accurately the results of
further experimentation. The storm of interest—both favorable and
nonfavorable—generated by the discoveries of Schaefer, Langmuir,
and Vonnegut has had and will continue to have far-reaching effects
on many aspects of society.
See also Airplane; Artificial insemination; In vitro plant culture;
Weather satellite.
Further Reading
Cloud seeding / 185
Cole, Stephen. “Mexico Results Spur New Looking at Rainmaking.”
Washington Post (January 22, 2001).

186 / Cloud seeding
Havens, Barrington S., James E. Jiusto, and Bernard Vonnegut. Early
History of Cloud Seeding. Socorro, N.Mex.: Langmuir Laboratory,
New Mexico Institute of Mining and Technology, 1978.
“Science and Technology: Cloudbusting.” The Economist (August 21,
1999).
Villiers, Marq de. Water: The Fate of Our Most Precious Resource. Boston:
Houghton Mifflin, 2000.

COBOL computer language
COBOL computer language
The invention: The first user-friendly computer programming language,
COBOL was originally designed to solve ballistics problems.
The people behind the invention:
Grace Murray Hopper (1906-1992), an American
mathematician
Howard Hathaway Aiken (1900-1973), an American
mathematician
Plain Speaking
187
Grace Murray Hopper, a mathematician, was a faculty member
at Vassar College when World War II (1939-1945) began. She enlisted
in the Navy and in 1943 was assigned to the Bureau of Ordnance
Computation Project, where she worked on ballistics problems.
In 1944, the Navy began using one of the first electronic
computers, the Automatic Sequence Controlled Calculator (ASCC),
designed by an International Business Machines (IBM) Corporation
team of engineers headed by Howard Hathaway Aiken, to solve
ballistics problems. Hopper became the third programmer of the
ASCC.
Hopper’s interest in computer programming continued after
the war ended. By the early 1950’s, Hopper’s work with programming
languages had led to her development of FLOW-MATIC, the
first English-language data processing compiler. Hopper’s work
on FLOW-MATIC paved the way for her later work with COBOL
(Common Business Oriented Language).
Until Hopper developed FLOW-MATIC, digital computer programming
was all machine-specific and was written in machine
code. A program designed for one computer could not be used on
another. Every program was both machine-specific and problemspecific
in that the programmer would be told what problem the
machine was going to be asked and then would write a completely
new program for that specific problem in the machine code.

188 / COBOL computer language
Grace Murray Hopper
Grace Brewster Murray was born in New York City in 1906.
As a child she revered her great-grandfather, a U.S. Navy admiral,
and her grandfather, an engineer. Her career melded their
professions.
She studied mathematics and physics at Vassar College,
earning a bachelor’s degree in 1928 and a master’s degree in
1930, when she married Vincent Foster Hopper. She accepted a
teaching post at Vassar but continued her studies, completing a
doctorate at Yale University in 1934. In 1943 she left academia
for the Navy and was assigned to the Bureau of Ordnance Computation
Project at Harvard University. She worked on the nation’s
first modern computer, the Mark I, and contributed to the
development of major new models afterward, including Sperry
Corporation’s ENIAC and UNIVAC. While still with the Navy
project at Harvard, Hopper participated in a minor incident
that forever marked computer slang. One day a moth became
caught in a switch, causing the computer to malfunction. She
and other technicians found it and ever after referred to correcting
mechanical glitches as “debugging.”
Hopper joined Sperry Corporation after the war and carried
out her seminal work with the FLOW-MATIC and COBOL
computer languages. Meanwhile, she retained her commission
in the Naval Reserves, helping the service incorporate computers
and COBOL into its armaments and administration systems.
She retired from the Navy in 1966 and from Sperry in
1971, but the Navy soon had her out of retirement on temporary
active duty to help with its computer systems. After her second
retirement, the Navy, grateful for her tireless service, promoted
her to rear admiral in 1985, the nation’s first woman admiral.
She was also awarded the Distinguished Service Cross by the
Department of Defense, the National Medal of Technology, and
the Legion of Merit. She became an inductee into the Engineering
and Science Hall of Fame in 1991. Hopper, nicknamed
Amazing Grace, died a year later.
Machine code was based on the programmer’s knowledge of the
physical characteristics of the computer as well as the requirements of
the problem to be solved; that is, the programmer had to know what
was happening within the machine as it worked through a series of

calculations, which relays tripped when and in what order, and what
mathematical operations were necessary to solve the problem. Programming
was therefore a highly specialized skill requiring a unique
combination of linguistic, reasoning, engineering, and mathematical
abilities that not even all the mathematicians and electrical engineers
who designed and built the early computers possessed.
While every computer still operates in response to the programming,
or instructions, built into it, which are formatted in machine
code, modern computers can accept programs written in nonmachine
code—that is, in various automatic programming languages. They
are able to accept nonmachine code programs because specialized
programs now exist to translate those programs into the appropriate
machine code. These translating programs are known as “compilers,”
or “assemblers,” and FLOW-MATIC was the first such program.
Hopper developed FLOW-MATIC after realizing that it would
be necessary to eliminate unnecessary steps in programming to
make computers more efficient. FLOW-MATIC was based, in part,
on Hopper’s recognition that certain elements, or commands, were
common to many different programming applications. Hopper theorized
that it would not be necessary to write a lengthy series of instructions
in machine code to instruct a computer to begin a series of
operations; instead, she believed that it would be possible to develop
commands in an assembly language in such a way that a programmer
could write one command, such as the word add, that
would translate into a sequence of several commands in machine
code. Hopper’s successful development of a compiler to translate
programming languages into machine code thus meant that programming
became faster and easier. From assembly languages such
as FLOW-MATIC, it was a logical progression to the development of
high-level computer languages, such as FORTRAN (Formula Translation)
and COBOL.
The Language of Business
COBOL computer language / 189
Between 1955 (when FLOW-MATIC was introduced) and 1959, a
number of attempts at developing a specific business-oriented language
were made. IBM and Remington Rand believed that the only
way to market computers to the business community was through

190 / COBOL computer language
the development of a language that business people would be
comfortable using. Remington Rand officials were especially committed
to providing a language that resembled English. None of
the attempts to develop a business-oriented language succeeded,
however, and by 1959 Hopper and other members of the U.S. Department
of Defense had persuaded representatives of various companies
of the need to cooperate.
On May 28 and 29, 1959, a conference sponsored by the Department
of Defense was held at the Pentagon to discuss the problem of
establishing a common language for the adaptation of electronic
computers for data processing. As a result, the first distribution of
COBOL was accomplished on December 17, 1959. Although many
people were involved in the development of COBOL, Hopper played
a particularly important role. She not only found solutions to technical
problems but also succeeded in selling the concept of a common
language from an administrative and managerial point of view. Hopper
recognized that while the companies involved in the commercial
development of computers were in competition with one another, the
use of a common, business-oriented language would contribute to
the growth of the computer industry as a whole, as well as simplify
the training of computer programmers and operators.
Consequences
COBOL was the first compiler developed for business data processing
operations. Its development simplified the training required
for computer users in business applications and demonstrated that
computers could be practical tools in government and industry as
well as in science. Prior to the development of COBOL, electronic
computers had been characterized as expensive, oversized adding
machines that were adequate for performing time-consuming mathematics
but lacked the flexibility that business people required.
In addition, the development of COBOL freed programmers not
only from the need to know machine code but also from the need to
understand the physical functioning of the computers they were using.
Programming languages could be written that were both machine-independent
and almost universally convertible from one
computer to another.

Finally, because Hopper and the other committee members worked
under the auspices of the Department of Defense, the software
was not copyrighted, and in a short period of time COBOL became
widely available to anyone who wanted to use it. It diffused rapidly
throughout the industry and contributed to the widespread adaptation
of computers for use in countless settings.
See also BASIC programming language; Colossus computer;
ENIAC computer; FORTRAN programming language; SAINT.
Further Reading
COBOL computer language / 191
Cohen, Bernard I., Gregory W. Welch, and Robert V. D. Campbell.
Makin’ Numbers: Howard Aiken: and the Computer. Cambridge,
Mass.: MIT Press, 1999.
Cohen, Bernard I. Howard Aiken: Portrait of a Computer Pioneer. Cambridge,
Mass.: MIT Press, 1999.
Ferguson, David E. “The Roots of COBOL.” Systems 3X World and As
World 17, no. 7 (July, 1989).
Yount, Lisa. A to Z of Women in Science and Math. New York: Facts on
File, 1999.

192
Color film
Color film
The invention: Aphotographic medium used to take full-color pictures.
The people behind the invention:
Rudolf Fischer (1881-1957), a German chemist
H. Siegrist (1885-1959), a German chemist and Fischer’s
collaborator
Benno Homolka (1877-1949), a German chemist
The Process Begins
Around the turn of the twentieth century, Arthur-Louis Ducos du
Hauron, a French chemist and physicist, proposed a tripack (threelayer)
process of film development in which three color negatives
would be taken by means of superimposed films. This was a subtractive
process. (In the “additive method” of making color pictures,
the three colors are added in projection—that is, the colors are formed
by the mixture of colored light of the three primary hues. In the
“subtractive method,” the colors are produced by the superposition
of prints.) In Ducos du Hauron’s process, the blue-light negative
would be taken on the top film of the pack; a yellow filter below it
would transmit the yellow light, which would reach a green-sensitive
film and then fall upon the bottom of the pack, which would be sensitive
to red light. Tripacks of this type were unsatisfactory, however,
because the light became diffused in passing through the emulsion
layers, so the green and red negatives were not sharp.
To obtain the real advantage of a tripack, the three layers must
be coated one over the other so that the distance between the bluesensitive
and red-sensitive layers is a small fraction of a thousandth
of an inch. Tripacks of this type were suggested by the early pioneers
of color photography, who had the idea that the packs would
be separated into three layers for development and printing. The
manipulation of such systems proved to be very difficult in practice.
It was also suggested, however, that it might be possible to develop
such tripacks as a unit and then, by chemical treatment, convert the
silver images into dye images.

Fischer’s Theory
One of the earliest subtractive tripack methods that seemed to
hold great promise was that suggested by Rudolf Fischer in 1912. He
proposed a tripack that would be made by coating three emulsions
on top of one another; the lowest one would be red-sensitive, the
middle one would be green-sensitive, and the top one would be bluesensitive.
Chemical substances called “couplers,” which would produce
dyes in the development process, would be incorporated into
the layers. In this method, the molecules of the developing agent, after
becoming oxidized by developing the silver image, would react
with the unoxidized form (the coupler) to produce the dye image.
The two types of developing agents described by Fischer are
paraminophenol and paraphenylenediamine (or their derivatives).
The five types of dye that Fischer discovered are formed when silver
images are developed by these two developing agents in the presence
of suitable couplers. The five classes of dye he used (indophenols,
indoanilines, indamines, indothiophenols, and azomethines)
were already known when Fischer did his work, but it was he who
discovered that the photographic latent image could be used to promote
their formulation from “coupler” and “developing agent.”
The indoaniline and azomethine types have been found to possess
the necessary properties, but the other three suffer from serious defects.
Because only p-phenylenediamine and its derivatives can be
used to form the indoaniline and azomethine dyes, it has become
the most widely used color developing agent.
Impact
Color film / 193
In the early 1920’s, Leopold Mannes and Leopold Godowsky
made a great advance beyond the Fischer process. Working on a
new process of color photography, they adopted coupler development,
but instead of putting couplers into the emulsion as Fischer
had, they introduced them during processing. Finally, in 1935, the
film was placed on the market under the name “Kodachrome,” a
name that had been used for an early two-color process.
The first use of the new Kodachrome process in 1935 was for 16millimeter
film. Color motion pictures could be made by the Koda-

194 / Color film
chrome process as easily as black-and-white pictures, because the
complex work involved (the color development of the film) was
done under precise technical control. The definition (quality of the
image) given by the process was soon sufficient to make it practical
for 8-millimeter pictures, and in 1936, Kodachrome film was introduced
in a 35-millimeter size for use in popular miniature cameras.
Soon thereafter, color processes were developed on a larger scale
and new color materials were rapidly introduced. In 1940, the Kodak
Research Laboratories worked out a modification of the Fischer
process in which the couplers were put into the emulsion layers.
These couplers are not dissolved in the gelatin layer itself, as the
Fischer couplers are, but are carried in small particles of an oily material
that dissolves the couplers, protects them from the gelatin,
and protects the silver bromide from any interaction with the couplers.
When development takes place, the oxidation product of the
developing agent penetrates into the organic particles and reacts
with the couplers so that the dyes are formed in small particles that
are dispersed throughout the layers. In one form of this material,
Ektachrome (originally intended for use in aerial photography), the
film is reversed to produce a color positive. It is first developed with
a black-and-white developer, then reexposed and developed with a
color developer that recombines with the couplers in each layer to
produce the appropriate dyes, all three of which are produced simultaneously
in one development.
In summary, although Fischer did not succeed in putting his theory
into practice, his work still forms the basis of most modern color
photographic systems. Not only did he demonstrate the general
principle of dye-coupling development, but the art is still mainly
confined to one of the two types of developing agent, and two of the
five types of dye, described by him.
See also Autochrome plate; Brownie camera; Infrared photography;
Instant photography.
Further Reading
Collins, Douglas. The Story of Kodak. New York: Harry N. Abrams,
1990.

Color film / 195
Glendinning, Peter. Color Photography: History, Theory, and Darkroom
Technique. Englewood Cliffs, N.J.: Prentice-Hall, 1985.
Wood, John. The Art of the Autochrome: The Birth of Color Photography.
Iowa City: University of Iowa Press, 1993.

196
Color television
Color television
The invention: System for broadcasting full-color images over the
airwaves.
The people behind the invention:
Peter Carl Goldmark (1906-1977), the head of the CBS research
and development laboratory
William S. Paley (1901-1990), the businessman who took over
CBS
David Sarnoff (1891-1971), the founder of RCA
The Race for Standardization
Although by 1928 color television had already been demonstrated
in Scotland, two events in 1940 mark that year as the beginning
of color television. First, on February 12, 1940, the Radio Corporation
of America (RCA) demonstrated its color television system
privately to a group that included members of the Federal Communications
Commission (FCC), an administrative body that had the
authority to set standards for an electronic color system. The demonstration
did not go well; indeed, David Sarnoff, the head of RCA,
canceled a planned public demonstration and returned his engineers
to the Princeton, New Jersey, headquarters of RCA’s laboratories.
Next, on September 1, 1940, the Columbia Broadcasting System
(CBS) took the first step to develop a color system that would become
the standard for the United States. On that day, CBS demonstrated
color television to the public, based on the research of an engineer,
Peter Carl Goldmark. Goldmark placed a set of spinning
filters in front of the black-and-white television images, breaking
them down into three primary colors and producing color television.
The audience saw what was called “additive color.”
Although Goldmark had been a researcher at CBS since January,
1936, he did not attempt to develop a color television system until
March, 1940, after watching the Technicolor motion picture Gone
with the Wind (1939). Inspired, Goldmark began to tinker in his tiny

CBS laboratory in the headquarters building in New York City.
If a decision had been made in 1940, the CBS color standard
would have been accepted as the national standard. The FCC was,
at that time, more concerned with trying to establish a black-andwhite
standard for television. Color television seemed decades away.
In 1941, the FCC decided to adopt standards for black-and-white
television only, leaving the issue of color unresolved—and the
doors to the future of color broadcasting wide open. Control of a potentially
lucrative market as well as personal rivalry threw William
S. Paley, the head of CBS, and Sarnoff into a race for the control of
color television. Both companies would pay dearly in terms of
money and time, but it would take until the 1960’s before the United
States would become a nation of color television watchers.
RCA was at the time the acknowledged leader in the development
of black-and-white television. CBS engineers soon discovered,
however, that their company’s color system would not work when
combined with RCA black-and-white televisions. In other words,
customers would need one set for black-and-white and one for
color. Moreover, since the color system of CBS needed more broadcast
frequency space than the black-and-white system in use, CBS
was forced to ask the FCC to allocate new channel space in the
ultrahigh frequency (UHF) band, which was then not being used. In
contrast, RCA scientists labored to make a compatible color system
that required no additional frequency space.
No Time to Wait
Color television / 197
Following the end of World War II, in 1945, the suburbanites who
populated new communities in America’s cities wanted television sets
right away; they did not want to wait for the government to decide on
a color standard and then wait again while manufacturers redesigned
assembly lines to make color sets. Rich with savings accumulated during
the prosperity of the war years, Americans wanted to spend their
money. After the war, the FCC saw no reason to open up proceedings
regarding color systems. Black-and-white was operational; customers
were waiting in line for the new electronic marvel. To give its engineers
time to create a compatible color system, RCA skillfully lobbied the
members of the FCC to take no action.

198 / Color television
There were other problems with the CBS mechanical color television.
It was noisy and large, and its color balance was hard to maintain.
CBS claimed that through further engineering work, it would
improve the actual sets. Yet RCA was able to convince other manufacturers
to support it in preference to CBS principally because of its
proven manufacturing track record.
In 1946, RCA demonstrated a new electronic color receiver with
three picture tubes, one for each of the primary colors. Color reproduction
was fairly true; although any movement on the screen
caused color blurring, there was little flicker. It worked, however,
and thus ended the invention phase of color television begun in
1940. The race for standardization would require seven more years
of corporate struggle before the RCA system would finally win
adoption as the national standard in 1953.
Impact
Through the 1950’s, black-and-white television remained the order
of the day. Through the later years of the decade, only the National
Broadcasting Company (NBC) television network was regularly
airing programs in color. Full production and presentation of
shows in color during prime time did not come until the mid-1960’s;
most industry observers date 1972 as the true arrival of color television.
By 1972, color sets were found in more than half the homes in the
United States. At that point, since color was so widespread, TV
Guide stopped tagging color program listings with a special symbol
and instead tagged only black-and-white shows, as it does to this
day. Gradually, only cheap, portable sets were made for black-andwhite
viewing, while color sets came in all varieties from tiny handheld
pocket televisions to mammoth projection televisions.
See also Autochrome plate; Community antenna television;
Communications satellite; Fiber-optics; FM radio; Radio; Television;
Transistor; Videocassette recorder.

Further Reading
Color television / 199
Burns, R. W. Television: An International History of the Formative Years.
London: Institution of Electrical Engineers in association with
the Science Museum, 1998.
Fisher, David E., and Marshall Fisher. Tube: The Invention of Television.
Washington, D.C.: Counterpoint, 1996.
Lewis, Tom. Empire of the Air: The Men Who Made Radio. New York:
HarperPerennial, 1993.
Lyons, Eugene. David Sarnoff: A Biography. New York: Harper and
Row, 1967.

200
Colossus computer
Colossus computer
The invention: The first all-electronic calculating device, the Colossus
computer was built to decipher German military codes
during World War II.
The people behind the invention:
Thomas H. Flowers, an electronics expert
Max H. A. Newman (1897-1984), a mathematician
Alan Mathison Turing (1912-1954), a mathematician
C. E. Wynn-Williams, a member of the Telecommunications
Research Establishment
An Undercover Operation
In 1939, during World War II (1939-1945), a team of scientists,
mathematicians, and engineers met at Bletchley Park, outside London,
to discuss the development of machines that would break the
secret code used in Nazi military communications. The Germans
were using a machine called “Enigma” to communicate in code between
headquarters and field units. Polish scientists, however, had
been able to examine a German Enigma and between 1928 and 1938
were able to break the codes by using electromechanical codebreaking
machines called “bombas.” In 1938, the Germans made the
Enigma more complicated, and the Polish were no longer able to
break the codes. In 1939, the Polish machines and codebreaking
knowledge passed to the British.
Alan Mathison Turing was one of the mathematicians gathered
at Bletchley Park to work on codebreaking machines. Turing was
one of the first people to conceive of the universality of digital computers.
He first mentioned the “Turing machine” in 1936 in an article
published in the Proceedings of the London Mathematical Society.
The Turing machine, a hypothetical device that can solve any
problem that involves mathematical computation, is not restricted
to only one task—hence the universality feature.
Turing suggested an improvement to the Bletchley codebreaking
machine, the “Bombe,” which had been modeled on the Polish

omba. This improvement increased the computing power of the
machine. The new codebreaking machine replaced the tedious
method of decoding by hand, which in addition to being slow,
was ineffective in dealing with complicated encryptions that were
changed daily.
Building a Better Mousetrap
Colossus computer / 201
The Bombe was very useful. In 1942, when the Germans started
using a more sophisticated cipher machine known as the “Fish,”
Max H. A. Newman, who was in charge of one subunit at Bletchley
Park, believed that an automated device could be designed to break
the codes produced by the Fish. Thomas H. Flowers, who was in
charge of a switching group at the Post Office Research Station at
Dollis Hill, had been approached to build a special-purpose electromechanical
device for Bletchley Park in 1941. The device was not
useful, and Flowers was assigned to other problems.
Flowers began to work closely with Turing, Newman, and C. E.
Wynn-Williams of the Telecommunications Research Establishment
(TRE) to develop a machine that could break the Fish codes. The
Dollis Hill team worked on the tape driving and reading problems,
and Wynn-Williams’s team at TRE worked on electronic counters
and the necessary circuitry. Their efforts produced the “Heath Robinson,”
which could read two thousand characters per second. The
Heath Robinson used vacuum tubes, an uncommon component in
the early 1940’s. The vacuum tubes performed more reliably and
rapidly than the relays that had been used for counters. Heath Robinson
and the companion machines proved that high-speed electronic
devices could successfully do cryptoanalytic work (solve decoding
problems).
Entirely automatic in operation once started, the Heath Robinson
was put together at Bletchley Park in the spring of 1943. The Heath
Robinson became obsolete for codebreaking shortly after it was put
into use, so work began on a bigger, faster, and more powerful machine:
the Colossus.
Flowers led the team that designed and built the Colossus in
eleven months at Dollis Hill. The first Colossus (Mark I) was a bigger,
faster version of the Heath Robinson and read about five thou-

202 / Colossus computer
sand characters per second. Colossus had approximately fifteen
hundred vacuum tubes, which was the largest number that had
ever been used at that time. Although Turing and Wynn-Williams
were not directly involved with the design of the Colossus, their
previous work on the Heath Robinson was crucial to the project,
since the first Colossus was based on the Heath Robinson.
Colossus became operational at Bletchley Park in December,
1943, and Flowers made arrangements for the manufacture of its
components in case other machines were required. The request for
additional machines came in March, 1944. The second Colossus, the
Mark II, was extensively redesigned and was able to read twentyfive
thousand characters per second because it was capable of performing
parallel operations (carrying out several different operations
at once, instead of one at a time); it also had a short-term
memory. The Mark II went into operation on June 1, 1944. More
machines were made, each with further modifications, until there
were ten. The Colossus machines were special-purpose, programcontrolled
electronic digital computers, the only known electronic
programmable computers in existence in 1944. The use of electronics
allowed for a tremendous increase in the internal speed of the
machine.
Impact
The Colossus machines gave Britain the best codebreaking machines
of World War II and provided information that was crucial
for the Allied victory. The information decoded by Colossus, the actual
messages, and their influence on military decisions would remain
classified for decades after the war.
The later work of several of the people involved with the Bletchley
Park projects was important in British computer development
after the war. Newman’s and Turing’s postwar careers were closely
tied to emerging computer advances. Newman, who was interested
in the impact of computers on mathematics, received a grant from
the Royal Society in 1946 to establish a calculating machine laboratory
at Manchester University. He was also involved with postwar
computer growth in Britain.
Several other members of the Bletchley Park team, including Tu-

ing, joined Newman at Manchester in 1948. Before going to Manchester
University, however, Turing joined Britain’s National Physical
Laboratory (NPL). At NPL, Turing worked on an advanced
computer known as the Pilot Automatic Computing Engine (Pilot
ACE). While at NPL, Turing proposed the concept of a stored program,
which was a controversial but extremely important idea in
computing. A “stored” program is one that remains in residence inside
the computer, making it possible for a particular program and
data to be fed through an input device simultaneously. (The Heath
Robinson and Colossus machines were limited by utilizing separate
input tapes, one for the program and one for the data to be analyzed.)
Turing was among the first to explain the stored-program
concept in print. He was also among the first to imagine how subroutines
could be included in a program. (A subroutine allows separate
tasks within a large program to be done in distinct modules; in
effect, it is a detour within a program. After the completion of the
subroutine, the main program takes control again.)
See also Apple II computer; Differential analyzer; ENIAC computer;
IBM Model 1401 computer; Personal computer; Supercomputer;
UNIVAC computer.
Further Reading
Colossus computer / 203
Carter, Frank. Codebreaking with the Colossus Computer: Finding the K-
Wheel Patterns—An Account of Some of the Techniques Used. Milton
Keynes, England: Bletchley Park Trust, 1997.
Gray, Paul. “Computer Scientist: Alan Turing.” Time 153, no. 12
(March 29, 1999).
Hodges, Andrew. Alan Turing: The Enigma. New York: Walker, 2000.
Sale, Tony. The Colossus Computer, 1943-1996: And How It Helped to
Break the German Lorenz Cipher in World War II. Cleobury Mortimer:
M&M Baldwin, 1998.

204
Communications satellite
Communications satellite
The invention: Telstar I, the world’s first commercial communications
satellite, opened the age of live, worldwide television by
connecting the United States and Europe.
The people behind the invention:
Arthur C. Clarke (1917- ), a British science-fiction writer
who in 1945 first proposed the idea of using satellites as
communications relays
John R. Pierce (1910- ), an American engineer who worked
on the Echo and Telstar satellite communications projects
Science Fiction?
In 1945, Arthur C. Clarke suggested that a satellite orbiting high
above the earth could relay television signals between different stations
on the ground, making for a much wider range of transmission
than that of the usual ground-based systems. Writing in the
February, 1945, issue of Wireless World, Clarke said that satellites
“could give television and microwave coverage to the entire
planet.”
In 1956, John R. Pierce at the Bell Telephone Laboratories of the
American Telephone & Telegraph Company (AT&T) began to urge
the development of communications satellites. He saw these satellites
as a replacement for the ocean-bottom cables then being used to
carry transatlantic telephone calls. In 1950, about one-and-a-half
million transatlantic calls were made, and that number was expected
to grow to three million by 1960, straining the capacity of the
existing cables; in 1970, twenty-one million calls were made.
Communications satellites offered a good, cost-effective alternative
to building more transatlantic telephone cables. On January 19,
1961, the Federal Communications Commission (FCC) gave permission
for AT&T to begin Project Telstar, the first commercial communications
satellite bridging the Atlantic Ocean. AT&T reached an
agreement with the National Aeronautics and Space Administration
(NASA) in July, 1961, in which AT&T would pay $3 million for

each Telstar launch. The Telstar project involved about four hundred
scientists, engineers, and technicians at the Bell Telephone
Laboratories, twenty more technical personnel at AT&T headquarters,
and the efforts of more than eight hundred other companies
that provided equipment or services.
Telstar 1 was shaped like a faceted sphere, was 88 centimeters in
diameter, and weighed 80 kilograms. Most of its exterior surface
(sixty of the seventy-four facets) was covered by 3,600 solar cells to
convert sunlight into 15 watts of electricity to power the satellite.
Each solar cell was covered with artificial sapphire to reduce the
damage caused by radiation. The main instrument was a two-way
radio able to handle six hundred telephone calls at a time or one
television channel.
The signal that the radio would send back to Earth was very
weak—less than one-thirtieth the energy used by a household light
bulb. Large ground antennas were needed to receive Telstar’s faint
signal. The main ground station was built by AT&T in Andover,
Maine, on a hilltop informally called “Space Hill.” A horn-shaped
antenna, weighing 380 tons, with a length of 54 meters and an open
end with an area of 1,097 square meters, was mounted so that it
could rotate to track Telstar across the sky. To protect it from wind
and weather, the antenna was built inside an inflated dome, 64 meters
in diameter and 49 meters tall. It was, at the time, the largest inflatable
structure ever built. A second, smaller horn antenna in
Holmdel, New Jersey, was also used.
International Cooperation
Communications satellite / 205
In February, 1961, the governments of the United States and England
agreed to let the British Post Office and NASA work together
to test experimental communications satellites. The British Post Office
built a 26-meter-diameter steerable dish antenna of its own design
at Goonhilly Downs, near Cornwall, England. Under a similar
agreement, the French National Center for Telecommunications
Studies constructed a ground station, almost identical to the Andover
station, at Pleumeur-Bodou, Brittany, France.
After testing, Telstar 1 was moved to Cape Canaveral, Florida,
and attached to the Thor-Delta launch vehicle built by the Douglas

206 / Communications satellite
Aircraft Company. The Thor-Delta was launched at 3:35 a.m. eastern
standard time (EST) on July 10, 1962. Once in orbit, Telstar 1 took
157.8 minutes to circle the globe. The satellite came within range of
the Andover station on its sixth orbit, and a television test pattern
was transmitted to the satellite at 6:26 p.m. EST. At 6:30 p.m. EST, a
tape-recorded black-and-white image of the American flag with the
Andover station in the background, transmitted from Andover to
Holmdel, opened the first television show ever broadcast by satellite.
Live pictures of U.S. vice president Lyndon B. Johnson and
other officials gathered at Carnegie Institution in Washington, D.C.,
followed on the AT&T program carried live on all three American
networks.
Up to the moment of launch, it was uncertain if the French station
would be completed in time to participate in the initial test. At 6:47
p.m. EST, however, Telstar’s signal was picked up by the station in
Pleumeur-Bodou, and Johnson’s image became the first television
transmission to cross the Atlantic. Pictures received at the French
station were reported to be so clear that they looked like they had
been sent from only forty kilometers away. Because of technical difficulties,
the English station was unable to receive a clear signal.
The first formal exchange of programming between the United
States and Europe occurred on July 23, 1962. This special eighteenminute
program, produced by the European Broadcasting Union,
consisted of live scenes from major cities throughout Europe and
was transmitted from Goonhilly Downs, where the technical difficulties
had been corrected, to Andover via Telstar.
On the previous orbit, a program entitled “America, July 23,
1962,” showing scenes from fifty television cameras around the
United States, was beamed from Andover to Pleumeur-Bodou and
seen by an estimated one hundred million viewers throughout Europe.
Consequences
Telstar 1 and the communications satellites that followed it revolutionized
the television news and sports industries. Before, television
networks had to ship film across the oceans, meaning delays of
hours or days between the time an event occurred and the broadcast

of pictures of that event on television on another continent. Now,
news of major significance, as well as sporting events, can be viewed
live around the world. The impact on international relations also
was significant, with world opinion becoming able to influence the
actions of governments and individuals, since those actions could
be seen around the world as the events were still in progress.
More powerful launch vehicles allowed new satellites to be placed
in geosynchronous orbits, circling the earth at a speed the same as
the earth’s rotation rate. When viewed from the ground, these satellites
appeared to remain stationary in the sky. This allowed continuous
communications and greatly simplified the ground antenna
system. By the late 1970’s, private individuals had built small antennas
in their backyards to receive television signals directly from the
satellites.
See also Artificial satellite; Cruise missile; Rocket; Weather satellite.
Further Reading
Communications satellite / 207
McAleer, Neil. Odyssey: The Authorised Biography of Arthur C. Clarke.
London: Victor Gollancz, 1992.
Pierce, John Robinson. The Beginnings of Satellite Communications.
San Francisco: San Francisco Press, 1968.
_____. Science, Art, and Communication. New York: C. N. Potter, 1968.

208
Community antenna television
Community antenna television
The invention: A system for connecting households in isolated areas
to common antennas to improve television reception, community
antenna television was a forerunner of modern cabletelevision
systems.
The people behind the invention:
Robert J. Tarlton, the founder of CATV in eastern Pennsylvania
Ed Parsons, the founder of CATV in Oregon
Ted Turner (1938- ), founder of the first cable superstation,
WTBS
Growing Demand for Television
Television broadcasting in the United States began in the late
1930’s. After delays resulting from World War II, it exploded into
the American public’s consciousness. The new medium relied primarily
on existing broadcasting stations that quickly converted
from radio to television formats. Consequently, the reception of television
signals was centralized in large cities. The demand for television
quickly swept across the country. Ownership of television receivers
increased dramatically, and those who could not afford their
own flocked to businesses, usually taverns, or to the homes of
friends with sets. People in urban areas had more opportunities to
view the new medium and had the advantage of more broadcasts
within the range of reception. Those in outlying regions were not so
fortunate, as they struggled to see fuzzy pictures and were, in some
cases, unable to receive a signal at all.
The situation for outlying areas worsened in 1948, when the Federal
Communications Commission (FCC) implemented a ban on all
new television stations while it considered how to expand the television
market and how to deal with a controversy over color reception.
This left areas without nearby stations in limbo, while people
in areas with established stations reaped the benefits of new programming.
The ban would remain in effect until 1952, when new
stations came under construction across the country.

Poor reception in some areas and the FCC ban on new station
construction together set the stage for the development of Community
Antenna Television (CATV). CATV did not have a glamorous
beginning. Late in 1949, two different men, frustrated by the slow
movement of television to outlying areas, set up what would become
the foundation of the multimillion-dollar cable industry.
Robert J. Tarlton was a radio salesman in Lansford, Pennsylvania,
about sixty-five miles from Philadelphia. He wanted to move
into television sales but lived in an area with poor reception. Together
with friends, he founded Panther Valley Television and set
up a master antenna in a mountain range that blocked the reception
of Philadelphia-based broadcasting. For an installation fee of $125
and a fee of $3 per month, Panther Valley Television offered residents
clear reception of the three Philadelphia stations via a coaxial
cable wired to their homes. At the same time, Ed Parsons, of KAST
radio in Astoria, Oregon, linked homes via coaxial cables to a master
antenna set up to receive remote broadcasts. Both systems offered
three channels, the major network affiliates, to subscribers. By
1952, when the FCC ban was lifted, some seventy CATV systems
provided small and rural communities with the wonders of television.
That same year, the National Cable Television Association was
formed to represent the interests of the young industry.
Early systems could carry only one to three channels. In 1953,
CATV began to use microwave relays, which could import distant
signals to add more variety and pushed system capability to twelve
channels. A system of towers began sprouting up across the country.
These towers could relay a television signal from a powerful
originating station to each cable system’s main antenna. This further
opened the reception available to subscribers.
Pay Television
Community antenna television / 209
The notion of pay television also began at this time. In 1951, the
FCC authorized a test of Zenith Radio Corporation’s Phonevision in
Chicago. Scrambled images could be sent as electronic impulses
over telephone lines, then unscrambled by devices placed in subscribers’
homes. Subscribers could order a film over the telephone
for a minimal cost, usually $1. Advertisers for the system promoted

210 / Community antenna television
the idea of films for the “sick, aged, and sitterless.” This early test
was a forerunner of the premium, or pay, channels of later decades.
Network opposition to CATV came in the late 1950’s. RCA chairman
David Sarnoff warned against a pay television system that
could soon fall under government regulation, as in the case of utilities.
In April, 1959, the FCC found no basis for asserting jurisdiction
or authority over CATV. This left the industry open to tremendous
growth.
By 1960, the industry included 640 systems with 700,000 subscribers.
Ten years later, 2,490 systems were in operation, serving
more than 4.5 million households. This accelerated growth came at
a price. In April, 1965, the FCC reversed itself and asserted authority
over microwave-fed CATV. A year later, the entire cable system
came under FCC control. The FCC quickly restricted the use of distant
signals in the largest hundred markets.
The FCC movement to control cable systems stemmed from the
agency’s desire to balance the television market. From the onset of
television broadcasting, the FCC strived to maintain a balanced programming
schedule. The goal was to create local markets in which
local affiliate stations prospered from advertising and other community
support and would not be unduly harmed by competition
from larger metropolitan stations. In addition, growth of the industry
ideally was to be uniform, with large and small cities receiving
equal consideration. Cable systems, particularly those that could receive
distant signals via microwave relay, upset the balance. For example,
a small Ohio town could receive New York channels as well
as Chicago channels via cable, as opposed to receiving only the
channels from one city.
The balance was further upset with the creation of a new communications
satellite, COMSAT, in 1963. This technology allowed a
signal to be sent to the satellite, retransmitted back to Earth, and
then picked up by a receiving station. This further increased the
range of cable offerings and moved the transmission of television
signals to a national scale, as microwave-relayed transmissions
worked best in a regional scope. These two factors led the FCC to
freeze the cable industry from new development and construction
in December, 1968. After 1972, when the cable freeze was lifted, the
greatest impact of CATV would be felt.

Ted Turner
Community antenna television / 211
“The whole idea of grand things always turned me on,” Ted
Turner said in a 1978 Playboy magazine interview. Irrepressible,
tenacious, and flamboyant, Turner was groomed from childhood
for grandness.
Born Robert Edward Turner III in 1938 in Cincinnati, Ohio,
he was raised by a harsh, demanding father who sent him to
military preparatory schools and insisted he study business at
Brown University instead of attending the U.S. Naval Academy,
as the son wanted. Known as “Terrible Ted” in
school for his high-energy, maverick ways, he became
an champion debater, expert sailor, and natural
leader. When the Turner Advertising Company failed
in 1960, and his father committed suicide, young
Turner took it over and parlayed it into an empire, acquiring
or creating television stations and revolutionizing
how they were broadcast to Americans.
From then on he acquired, innovated, and, often,
shocked. He bought the Atlanta Braves baseball team
and Hawks basketball team, often angering sports
executives with his recruiting methods, earning the
nicknames “Mouth of the South” and “Captain Outrageous”
for his assertiveness. He won the prestigious America’s Cup in
1977 at the helm of the yacht Courageous. He bought Metro-
Golden-Mayer/United Artists and incensed movie purists by
having black-and-white classics “colorized.” In 1995 he concluded
a $7.5 billion merger of Turner Broadcasting and Time
Warner and set about an insult-slinging business war with another
media tycoon, Rupert Murdoch. Meanwhile, he went
through three marriages, the last to movie star Jane Fonda, and
became the largest private landholder in the nation, with luxury
homes in six states.
However, Turner’s life was not all acquisition. He started a
charitable foundation and sponsored the Olympics-like Goodwill
Games between the United States and the Soviet Union to
improve relations, for which Time magazine named him its man
of the year in 1991. However, Turner’s grandest shocker came
in 1997 when he promised to donate $1 billion—$100 million
each year for a decade—to the United Nations to help in feeding
the poor, resettling refugees, and eradicating land mines.
And he publicly challenged other super-rich people to use their
vast wealth similarly.
(George Bennett)

212 / Community antenna television
Impact
The founding of cable television had a two-tier effect on the
American public. The immediate impact of CATV was the opening
of television to areas cut off from network broadcasting as a result of
distance or topographical obstructions. Cable brought television to
those who would have otherwise missed the early years of the medium.
As technology furthered the capabilities of the industry, a second
impact emerged. Along with the 1972 lifting of the ban on cable expansion,
the FCC established strict guidelines for the advancement
of the industry. Issuing a 500-page blueprint for the expansion of cable,
the FCC included limits on the use of imported distant signals,
required the blacking out of some specific programs (films and serials,
for example), and limited pay cable to films that were more than
two years old and to sports.
Another component of the guidelines required all systems that
went into operation after March, 1972 (and all systems by March,
1977), to provide public access channels for education and local
government. In addition, channels were to be made available for
lease. These access channels opened information to subscribers that
would not normally be available. Local governments and school
boards began to broadcast meetings, and even high school athletics
soon appeared via public access channels. These channels also
provided space to local educational institutions for home-based
courses in a variety of disciplines.
Cable Communications Policy Act
Further FCC involvement came in the 1984 Cable Communications
Policy Act, which deregulated the industry and opened the
door for more expansion. This act removed local control over cable
service rates and virtually made monopolies out of local providers
by limiting competition. The late 1980’s brought a new technology,
fiber optics, which promised to further advance the industry by increasing
the quality of cable services and channel availability.
One area of the cable industry, pay television, took off in the
1970’s and early 1980’s. The first major pay channel was developed

Community antenna television / 213
by the media giant Time-Life. It inaugurated Home Box Office
(HBO) in 1975 as the first national satellite interconnected network.
Early HBO programming primarily featured films but included no
films less than two years old (meeting the 1972 FCC guidelines), no
serials, and no advertisements. Other premium movie channels followed,
including Showtime, Cinemax, and The Movie Channel. By
the late 1970’s, cable systems offered multiple premium channels to
their subscribers.
Superstations were another component of the cable industry that
boomed in the 1970’s and 1980’s. The first, WTBS, was owned and
operated by Ted Turner and broadcast from Atlanta, Georgia. It emphasized
films and reruns of old television series. Cable systems
that broadcast WTBS were asked to allocate the signal to channel 17,
thus creating uniformity across the country for the superstation.
Chicago’s WGN and New York City’s WOR soon followed, gaining
access to homes across the nation via cable. Both these superstations
emphasized sporting events in the early years and expanded to include
films and other entertainment in the 1980’s.
Both pay channels and superstations transmitted via satellites
(WTBS leased space from RCA, for example) and were picked up by
cable systems across the country. Other stations with broadcasts intended
solely for the cable industry opened in the 1980’s. Ted Turner
started the Cable News Network in 1980 and followed with the allnews
network Headline News. He added another channel with the
Turner Network Television (TNT) in 1988. Other 1980’s additions
included The Disney Channel, ESPN, The Entertainment Channel,
The Discovery Channel, and Lifetime. The Cable-Satellite Public Affairs
Network (C-SPAN) enhanced the cable industry’s presence in
Washington, D.C., by broadcasting sessions of the House of Representatives.
Specialized networks for particular audiences also developed.
Music Television (MTV), featuring songs played along with video
sequences, premiered in 1981. Nickelodeon, a children’s channel,
and VH-1, a music channel aimed at baby boomers rather than
MTV’s teenage audience, reflected the movement toward specialization.
Other specialized channels, such as the Sci-Fi Channel and the
Comedy Channel, went even further in targeting specific audiences.

214 / Community antenna television
Cable and the Public
The impact on the American public was tremendous. Information
and entertainment became available around the clock. Cable
provided a new level of service, information, and entertainment unavailable
to nonsubscribers. One phenomenon that exploded in the
late 1980’s was home shopping. Via The Home Shopping Club and
QVC, two shopping channels offered through cable television, the
American public could order a full range of products. Everything
from jewelry to tools and home cleaning supplies to clothing and
electronics was available to anyone with a credit card. Americans
could now go shopping from home.
The cable industry was not without its competitors and critics. In
the 1980’s, the videocassette recorder (VCR) opened the viewing
market. Prerecorded cassettes of recent film releases as well as classics
were made available for purchase or for a small rental fee. National
chains of video rental outlets, such as Blockbuster Video and
Video Towne, offered thousands of titles for rent. Libraries also began
to stock films. This created competition for the cable industry, in
particular the premium movie channels. To combat this competition,
channels began to offer original productions unavailable on
videocassette. The combined effect of the cable industry and the
videocassette market was devastating to the motion picture industry.
The wide variety of programming available at home encouraged
the American public, especially baby boomers with children,
to stay home and watch cable or rented films instead of going to theaters.
Critics of the cable industry seized on the violence, sexual content,
and graphic language found in some of cable’s offerings. One
parent responded by developing a lockout device that could make
certain channels unavailable to children. Some premium channels
developed an after-hours programming schedule that aired adulttheme
programming only late at night. Another criticism stemmed
from the repetition common on pay channels. As a result of the limited
supply of and large demand for films, pay channels were forced
to repeat programs several times within a month and to rebroadcast
films that were several years old. This led consumers to question the
value of the additional monthly fee paid for such channels. To com-

at the problem, premium channels increased efforts aimed at original
production and added more films that had not been box-office hits.
By the early 1990’s, as some eleven thousand cable systems were
serving 56.2 million subscribers, a new cry for regulation began. Debates
over services and increasingly high rates led the FCC and
Congress to investigate the industry, opening the door for new
guidelines on the cable industry. The non-cable networks—American
Broadcasting Company (ABC), Columbia Broadcasting System
(CBS), National Broadcasting Company (NBC), and newcomer
Fox—stressed their concerns about the cable industry. These networks
provided free programming, and cable systems profited
from inclusion of network programming. Television industry representatives
expressed the opinion that cable providers should pay
for the privilege of retransmitting network broadcasts.
The impact on cable’s subscribers, especially concerning monthly
cable rates, came under heavy debate in public and government forums.
The administration in Washington, D.C., expressed concern
that cable rates had risen too quickly and for no obvious reason other
than profit-seeking by what were essentially monopolistic local cable
systems. What was clear was that the cable industry had transformed
the television experience and was going to remain a powerful force
within the medium. Regulators and television industry leaders were
left to determine how to maintain an equitable coexistence within the
medium.
See also Color television; Communications satellite; Fiber-optics;
Telephone switching; Television.
Further Reading
Community antenna television / 215
Baldwin, Thomas F., and D. Stevens McVoy. Cable Communication.
Englewood Cliffs, N.J.: Prentice-Hall, 1983.
Brenner, Daniel L., and Monroe E. Price. Cable Television and Other
Nonbroadcast Video: Law and Policy. New York: Clark Boardman,
1986.
Burns, R. W. Television: An International History of the Formative Years.
London: Institution of Electrical Engineers in Association with
the Science Museum, 1998.

216 / Community antenna television
Coleman, Wim. The Age of Broadcasting: Television. Carlisle, Mass.:
Discovery Enterprises, 1997.
Negrine, Ralph M., ed. Cable Television and the Future of Broadcasting.
New York: St. Martin’s Press, 1985.
Sconce, Jeffrey. Haunted Media: Electronic Presence from Telegraphy to
Television. Durham, N.C.: Duke University Press, 2000.
Whittemore, Hank. CNN: The Inside Story. Boston: Little, Brown,
1990.

Compact disc
Compact disc
The invention: A plastic disk on which digitized music or computer
data is stored.
The people behind the invention:
Akio Morita (1921- ), a Japanese physicist and engineer
who was a cofounder of Sony
Wisse Dekker (1924- ), a Dutch businessman who led the
Philips company
W. R. Bennett (1904-1983), an American engineer who was a
pioneer in digital communications and who played an
important part in the Bell Laboratories research program
Digital Recording
217
The digital system of sound recording, like the analog methods
that preceded it, was developed by the telephone companies to improve
the quality and speed of telephone transmissions. The system
of electrical recording introduced by Bell Laboratories in the 1920s
was part of this effort. Even Edison’s famous invention of the phonograph
in 1877 was originally conceived as an accompaniment to
the telephone. Although developed within the framework of telephone
communications, these innovations found wide applications
in the entertainment industry.
The basis of the digital recording system was a technique of sampling
the electrical waveforms of sound called PCM, or pulse code
modulation. PCM measures the characteristics of these waves and
converts them into numbers. This technique was developed at Bell
Laboratories in the 1930’s to transmit speech. At the end of World
War II, engineers of the Bell System began to adapt PCM technology
for ordinary telephone communications.
The problem of turning sound waves into numbers was that of
finding a method that could quickly and reliably manipulate millions
of them. The answer to this problem was found in electronic computers,
which used binary code to handle millions of computations in a
few seconds. The rapid advance of computer technology and the

218 / Compact disc
semiconductor circuits that gave computers the power to handle
complex calculations provided the means to bring digital sound technology
into commercial use. In the 1960’s, digital transmission and
switching systems were introduced to the telephone network.
Pulse coded modulation of audio signals into digital code achieved
standards of reproduction that exceeded even the best analog system,
creating an enormous dynamic range of sounds with no distortion
or background noise. The importance of digital recording went
beyond the transmission of sound because it could be applied to all
types of magnetic recording in which the source signal is transformed
into an electric current. There were numerous commercial
applications for such a system, and several companies began to explore
the possibilities of digital recording in the 1970’s.
Researchers at the Sony, Matsushita, and Mitsubishi electronics
companies in Japan produced experimental digital recording systems.
Each developed its own PCM processor, an integrated circuit
that changes audio signals into digital code. It does not continuously
transform sound but instead samples it by analyzing thousands
of minute slices of it per second. Sony’s PCM-F1 was the first
analog-to-digital conversion chip to be produced. This gave Sony a
lead in the research into and development of digital recording.
All three companies had strong interests in both audio and video
electronics equipment and saw digital recording as a key technology
because it could deal with both types of information simultaneously.
They devised recorders for use in their manufacturing operations.
After using PCM techniques to turn sound into digital code, they recorded
this information onto tape, using not magnetic audio tape but
the more advanced video tape, which could handle much more information.
The experiments with digital recording occurred simultaneously
with the accelerated development of video recording technology
and owed much to the enhanced capabilities of video recorders.
At this time, videocassette recorders were being developed in
several corporate laboratories in Japan and Europe. The Sony Corporation
was one of the companies developing video recorders at this
time. Its U-matic machines were successfully used to record digitally.
In 1972, the Nippon Columbia Company began to make its master recordings
digitally on an Ampex video recording machine.

Links Among New Technologies
Compact disc / 219
There were powerful links between the new sound recording
systems and the emerging technologies of storing and retrieving
video images. The television had proved to be the most widely used
and profitable electronic product of the 1950’s, but with the market
for color television saturated by the end of the 1960’s, manufacturers
had to look for a replacement product. A machine to save and replay
television images was seen as the ideal companion to the family
TV set. The great consumer electronics companies—General
Electric and RCA in the United States, Philips and Telefunken in Europe,
and Sony and Matsushita in Japan—began experimental programs
to find a way to save video images.
RCA’s experimental teams took the lead in developing an optical
videodisc system, called Selectavision, that used an electronic stylus
to read changes in capacitance on the disc. The greatest challenge to
them came from the Philips company of Holland. Its optical videodisc
used a laser beam to read information on a revolving disc, in
which a layer of plastic contained coded information. With the aid
of the engineering department of the Deutsche Grammophon record
company, Philips had an experimental laser disc in hand by
1964.
The Philips Laservision videodisc was not a commercial success,
but it carried forward an important idea. The research and engineering
work carried out in the laboratories at Eindhoven in Holland
proved that the laser reader could do the job. More important,
Philips engineers had found that this fragile device could be mass
produced as a cheap and reliable component of a commercial product.
The laser optical decoder was applied to reading the binary
codes of digital sound. By the end of the 1970’s, Philips engineers
had produced a working system.
Ten years of experimental work on the Laservision system proved
to be a valuable investment for the Philips corporation. Around
1979, it started to work on a digital audio disc (DAD) playback system.
This involved more than the basic idea of converting the output
of the PCM conversion chip onto a disc. The lines of pits on the
compact disc carry a great amount of information: the left- and
right-hand tracks of the stereo system are identified, and a sequence

220 / Compact disc
of pits also controls the motor speed and corrects any error in the laser
reading of the binary codes.
This research was carried out jointly with the Sony Corporation
of Japan, which had produced a superior method of encoding digital
sound with its PCM chips. The binary codes that carried the information
were manipulated by Sony’s sixteen-bit microprocessor.
Its PCM chip for analog-to-digital conversion was also employed.
Together, Philips and Sony produced a commercial digital playback
record that they named the compact disc. The name is significant, as
it does more than indicate the size of the disc—it indicates family
ties with the highly successful compact cassette. Philips and Sony
had already worked to establish this standard in the magnetic tape
format and aimed to make their compact disc the standard for digital
sound reproduction.
Philips and Sony began to demonstrate their compact digital disc
(CD) system to representatives of the audio industry in 1981. They
were not alone in digital recording. The Japanese Victor Company, a
subsidiary of Matsushita, had developed a version of digital recording
from its VHD video disc design. It was called audio high density
disc (AHD). Instead of
the small CD disc, the AHD
system used a ten-inch vinyl
disc. Each digital recording
system used a different
PCM chip with a
different rate of sampling
the audio signal.
The recording and electronics
industries’ decision
to standardize on the Philips/Sony
CD system was
therefore a major victory for
these companies and an important
event in the digital
era of sound recording.
Sony had found out the
hard way that the technical
performance of an innova-
Although not much larger than a 3.25-inch floppy
disk, a compact disk can store more than five hundred
times as much data. (PhotoDisc)

tion is irrelevant when compared with the politics of turning it into
an industrywide standard. Although the pioneer in videocassette
recorders, Sony had been beaten by its rival, Matsushita, in establishing
the video recording standard. This mistake was not repeated
in the digital standards negotiations, and many companies were
persuaded to license the new technology. In 1982, the technology
was announced to the public. The following year, the compact disc
was on the market.
The Apex of Sound Technology
Compact disc / 221
The compact disc represented the apex of recorded sound technology.
Simply put, here at last was a system of recording in which
there was no extraneous noise—no surface noise of scratches and
pops, no tape hiss, no background hum—and no damage was done
to the recording as it was played. In principle, a digital recording
will last forever, and each play will sound as pure as the first. The
compact disc could also play much longer than the vinyl record or
long-playing cassette tape.
Despite these obvious technical advantages, the commercial success
of digital recording was not ensured. There had been several
other advanced systems that had not fared well in the marketplace,
and the conspicuous failure of quadrophonic sound in the 1970’s
had not been forgotten within the industry of recorded sound. Historically,
there were two key factors in the rapid acceptance of a new
system of sound recording and reproduction: a library of prerecorded
music to tempt the listener into adopting the system and a
continual decrease in the price of the playing units to bring them
within the budgets of more buyers.
By 1984, there were about a thousand titles available on compact
disc in the United States; that number had doubled by 1985. Although
many of these selections were classical music—it was naturally
assumed that audiophiles would be the first to buy digital
equipment—popular music was well represented. The first CD available
for purchase was an album by popular entertainer Billy Joel.
The first CD-playing units cost more than $1,000, but Akio Morita
of Sony was determined that the company should reduce the
price of players even if it meant selling them below cost. Sony’s

222 / Compact disc
Akio Morita
Akio Morita was born in Nagoya, Japan, in 1921 into a family
owning one of the country’s oldest, most prosperous sake
breweries. As the eldest son, Morita was expected to take over
its management from his father. However, business did not interest
him as a child. Electronics did, especially radios. He made
his own radio and phonograph and resolved to be a scientist.
He succeeded, but in an ironic twist, he also became one of the
twentieth century’s most successful businessmen.
After taking a degree in physics from Osaka Imperial University
in 1944, he worked at the Naval Research Center. There
he met Masaru Ibuka. Although Ibuka was twelve years older
and much more reserved in temperament, the two became fast
friends. After World War II, they borrowed the equivalent of
about $500 from Morita’s father and opened the Tokyo Telecommunications
Company, making voltmeters and, later, tape
recorders.
To help along sluggish sales, Morita visited local schools to
demonstrate the tape recorder’s usefulness in teaching. He was
so successful that a third of Japan’s elementary schools bought
them. From then on, Morita, as vice president of the company,
was the lead man in marketing and sales strategy. He bought
rights from West Electric Company to manufacture transistors
in 1954, and soon the company was turning out transistor radios.
Sales soared. They changed the name to Sony (based on
the Latin word for sound, sonus) because it was more memorable.
Despite an American bias against Japanese products—
which many Americans regarded as shoddy imitations—Morita
launched Sony America in 1960. In 1963 Sony became the first
Japanese company to sell its stock in America and in 1970 the
first to be listed on the New York Stock Exchange, opening an
American factory two years later. Morita became president of
Sony Corporation in 1971 and board chairman in 1976.
In 1984 Sony earnings exceeded $5 billion, a ten-million percent
increase in worth in less than forty years. As important for
Japanese industry and national honor, Morita and Sony moved
Japanese electronics into leading edge of technical sophistication
and craftsmanship.

audio engineering department improved the performance of the
players while reducing size and cost. By 1984, Sony had a small CD
unit on the market for $300. Several of Sony’s competitors, including
Matsushita, had followed its lead into digital reproduction.
There were several compact disc players available in 1985 that cost
less than $500. Sony quickly applied digital technology to the popular
personal stereo and to automobile sound systems. Sales of CD
units increased roughly tenfold from 1983 to 1985.
Impact on Vinyl Recording
Compact disc / 223
When the compact disc was announced in 1982, the vinyl record
was the leading form of recorded sound, with 273 million units sold
annually compared to 125 million prerecorded cassette tapes. The
compact disc sold slowly, beginning with 800,000 units shipped in
1983 and rising to 53 million in 1986. By that time, the cassette tape
had taken the lead, with slightly fewer than 350 million units. The
vinyl record was in decline, with only about 110 million units
shipped. Compact discs first outsold vinyl records in 1988. In the ten
years from 1979 to 1988, the sales of vinyl records dropped nearly 80
percent. In 1989, CDs accounted for more than 286 million sales, but
cassettes still led the field with total sales of 446 million. The compact
disc finally passed the cassette in total sales in 1992, when more
than 300 million CDs were shipped, an increase of 22 percent over
the figure for 1991.
The introduction of digital recording had an invigorating effect
on the industry of recorded sound, which had been unable to fully
recover from the slump of the late 1970’s. Sales of recorded music
had stagnated in the early 1980’s, and an industry accustomed to
steady increases in output became eager to find a new product or
style of music to boost its sales. The compact disc was the product to
revitalize the market for both recordings and players. During the
1980’s, worldwide sales of recorded music jumped from $12 billion
to $22 billion, with about half of the sales volume accounted for by
digital recordings by the end of the decade.
The success of digital recording served in the long run to undermine
the commercial viability of the compact disc. This was a playonly
technology, like the vinyl record before it. Once users had be-

224 / Compact disc
come accustomed to the pristine digital sound, they clamored for
digital recording capability. The alliance of Sony and Philips broke
down in the search for a digital tape technology for home use. Sony
produced a digital tape system called DAT, while Philips responded
with a digital version of its compact audio tape called DCC. Sony
answered the challenge of DCC with its Mini Disc (MD) product,
which can record and replay digitally.
The versatility of digital recording has opened up a wide range of
consumer products. Compact disc technology has been incorporated
into the computer, in which CD-ROM readers convert the digital
code of the disc into sound and images. Many home computers have
the capability to record and replay sound digitally. Digital recording
is the basis for interactive audio/video computer programs in which
the user can interface with recorded sound and images. Philips has
established a strong foothold in interactive digital technology with its
CD-I (compact disc interactive) system, which was introduced in
1990. This acts as a multimedia entertainer, providing sound, moving
images, games, and interactive sound and image publications such as
encyclopedias. The future of digital recording will be broad-based
systems that can record and replay a wide variety of sounds and images
and that can be manipulated by users of home computers.
See also Cassette recording; Dolby noise reduction; Electronic
synthesizer; FM radio; Laser-diode recording process; Optical disk;
Transistor; Videocassette recorder; Walkman cassette player.
Further Reading
Copeland, Peter. Sound Recordings. London: British Library, 1991.
Heerding, A. A Company of Many Parts. Cambridge: Cambridge University
Press, 1998.
Marshall, David V. Akio Morita and Sony. Watford: Exley, 1995.
Morita, Akio, with Edwin M. Reingold, and Mitsuko Shimomura.
Made in Japan: Akio Morita and Sony. London: HarperCollins, 1994.
Nathan, John. Sony: The Private Life. Boston, Mass.: Houghton Mifflin,
1999.
Schlender, Brenton R. “How Sony Keeps the Magic Going.” Fortune
125 (February 24, 1992).

Compressed-air-accumulating
power plant
Compressed-air-accumulating power plant
The invention: Plants that can be used to store energy in the form
of compressed air when electric power demand is low and use it
to produce energy when power demand is high.
The organization behind the invention:
Nordwestdeutsche Kraftwerke, a Germany company
Power, Energy Storage, and Compressed Air
225
Energy, which can be defined as the capacity to do work, is essential
to all aspects of modern life. One familiar kind of energy, which
is produced in huge amounts by power companies, is electrical energy,
or electricity. Most electricity is produced in a process that consists
of two steps. First, a fossil fuel such as coal is burned and the resulting
heat is used to make steam. Then, the steam is used to
operate a turbine system that produces electricity. Electricity has
myriad applications, including the operation of heaters, home appliances
of many kinds, industrial machinery, computers, and artificial
illumination systems.
An essential feature of electricity manufacture is the production
of the particular amount of electricity that is needed at a given time.
If moment-to-moment energy requirements are not met, the city or
locality involved will experience a “blackout,” the most obvious
feature of which is the loss of electrical lighting. To prevent blackouts,
it is essential to store extra electricity at times when power production
exceeds power demands. Then, when power demands exceed
the capacity to make energy by normal means, stored energy
can be used to make up the difference.
One successful modern procedure for such storage is the compressed-air-accumulation
process, pioneered by the Nordwestdeutsche
Kraftwerke company’s compressed-air-accumulating power
plant, which opened in December, 1978. The plant, which is
located in Huntorf, Germany (at the time, West Germany), makes
compressed air during periods of low electricity demand, stores the

226 / Compressed-air-accumulating power plant
air in an underground cavern, and uses it to produce extra electricity
during periods of high demand.
Plant Operation and Components
The German 300-megawatt compressed-air-accumulating power
plant in Huntorf produces extra electricity from stored compressed
air that will provide up to four hours per day of local peak electricity
needs. The energy-storage process, which is vital to meeting very
high peak electric power demands, is viable for electric power
plants whose total usual electric outputs range from 25 megawatts
to the 300 megawatts produced at Huntorf. It has been suggested,
however, that the process is most suitable for 25- to 50-megawatt
plants.
The energy-storage procedure used at Huntorf is quite simple.
All the surplus electricity that is made in nonpeak-demand periods
is utilized to drive an air compressor. The compressor pumps air
from the surrounding atmosphere into an airtight underground
storage cavern. When extra electricity is required, the stored compressed
air is released and passed through a heating unit to be
warmed, after which it is used to run gas-turbine systems that produce
electricity. This sequence of events is the same as that used in
any gas-turbine generating system; the only difference is that the
compressed air can be stored for any desired period of time rather
than having to be used immediately.
One requirement of any compressed-air-accumulating power
plant is an underground storage chamber. The Huntorf plant utilizes
a cavern that was hollowed out some 450 meters below the surface
of the earth. The cavern was created by drilling a hole into an
underground salt deposit and pumping in water. The water dissolved
the salt, and the resultant saltwater solution (brine) was
pumped out of the deposit. The process of pumping in water and removing
brine was continued until the cavern reached the desired
size. This type of storage cavern is virtually leak-free. The preparation
of such underwater salt-dome caverns has been performed
roughly since the middle of the twentieth century. Until the Huntorf
endeavor, such caves were used to stockpile petroleum and natural
gas for later use. It is also possible to use mined, hard-rock caverns

for compressed-air accumulation when it is necessary to compress
air to pressures higher than those that can be maintained effectively
in a salt-dome cavern.
The essential machinery that must be added to conventional
power plants to turn them into compressed-air-accumulating power
plants are motor-driven air compressors and gas turbine generating
systems. This equipment must be connected appropriately so that
in the storage mode, the overall system will compress air for storage
in the underground cavern, and in the power-production mode, the
system will produce electricity from the stored compressed air.
Large compressed-air-accumulating power plants require specially
constructed machinery. For example, the compressors that
are used at Huntorf were developed specifically for that plant by
Sulzer, a Swiss company. When the capacity of such plants is no
higher than 50 megawatts, however, standard, readily available
components can be used. This means that relatively small compressed-air-accumulating
power plants can be constructed for a reasonable
cost.
Consequences
Compressor
Compressed-air-accumulating power plant / 227
Air
Electricity
Out
Electricity
In
Exhaust Stack
Recuperator
Clutch Motor Clutch
Generator
Turbine
Valve Valve
Combuster
Burning Fuel
Schematic of a compressed-air-accumulating power plant.
The development of compressed-air-accumulating power plants
has had a significant impact on the electric power industry, adding to
its capacity to store energy. The main storage methods available prior
to the development of compressed-air-accumulation methodology
were batteries and water that was pumped uphill (hydro-storage). Battery
technology is expensive, and its capacity is insufficient for major,
long-term power storage. Hydro-storage is a more viable technology.

228 / Compressed-air-accumulating power plant
Compressed-air energy-storage systems have several advantages
over hydro-storage. First, they can be used in areas where flat terrain
makes it impossible to use hydro-storage. Second, compressedair
storage is more efficient than hydro-storage. Finally, the fact that
standard plant components can be used, along with several other
factors, means that 25- to 50-megawatt compressed-air storage plants
can be constructed much more quickly and cheaply than comparable
hydro-storage plants.
The attractiveness of compressed-air-accumulating power plants
has motivated efforts to develop hard-rock cavern construction
techniques that cut costs and make it possible to use high-pressure
air storage. In addition, aquifers (underground strata of porous rock
that normally hold groundwater) have been used successfully for
compressed-air storage. It is expected that compressed-air-accumulating
power plants will be widely used in the future, which will
help to decrease pollution and cut the use of fossil fuels.
See also Alkaline storage battery; Breeder reactor; Fuel cell; Geothermal
power; Heat pump; Nuclear power plant; Tidal power
plant.
Further Reading
“Compressed Air Stores Electricity.” Popular Science 242, no. 5 (May,
1993).
Lee, Daehee. “Power to Spare: Compressed Air Energy Storage.”
Mechanical Engineering 113, no. 7 (July, 1991).
Shepard, Sam, and Septimus van der Linden. “Compressed Air Energy
Storage Adapts Proven Technology to Address Market Opportunities.”
Power Engineering 105, no. 4 (April, 2001).
Zink, John C. “Who Says You Can’t Store Electricity?” Power Engineering
101, no. 3 (March, 1997).

Computer chips
Computer chips
The invention: Also known as a microprocessor, a computer chip
combines the basic logic circuits of a computer on a single silicon
chip.
The people behind the invention:
Robert Norton Noyce (1927-1990), an American physicist
William Shockley (1910-1989), an American coinventor of the
transistor who was a cowinner of the 1956 Nobel Prize in
Physics
Marcian Edward Hoff, Jr. (1937- ), an American engineer
Jack St. Clair Kilby (1923- ), an American researcher and
assistant vice president of Texas Instruments
The Shockley Eight
229
The microelectronics industry began shortly after World War II
with the invention of the transistor. While radar was being developed
during the war, it was discovered that certain crystalline substances,
such as germanium and silicon, possess unique electrical
properties that make them excellent signal detectors. This class of
materials became known as “semiconductors,” because they are
neither conductors nor insulators of electricity.
Immediately after the war, scientists at Bell Telephone Laboratories
began to conduct research on semiconductors in the hope that
they might yield some benefits for communications. The Bell physicists
learned to control the electrical properties of semiconductor
crystals by “doping” (treating) them with minute impurities. When
two thin wires for current were attached to this material, a crude device
was obtained that could amplify the voice. The transistor, as
this device was called, was developed late in 1947. The transistor
duplicated many functions of vacuum tubes; it was also smaller, required
less power, and generated less heat. The three Bell Laboratories
scientists who guided its development—William Shockley,
Walter H. Brattain, and John Bardeen—won the 1956 Nobel Prize in
Physics for their work.

230 / Computer chips
Shockley left Bell Laboratories and went to Palo Alto, California,
where he formed his own company, Shockley Semiconductor Laboratories,
which was a subsidiary of Beckman Instruments. Palo Alto
is the home of Stanford University, which, in 1954, set aside 655
acres of land for a high-technology industrial area known as Stanford
Research Park. One of the first small companies to lease a site
there was Hewlett-Packard. Many others followed, and the surrounding
area of Santa Clara County gave rise in the 1960’s and
1970’s to a booming community of electronics firms that became
known as “Silicon Valley.” On the strength of his prestige, Shockley
recruited eight young scientists from the eastern United States to
work for him. One was Robert Norton Noyce, an Iowa-bred physicist
with a doctorate from the Massachusetts Institute of Technology.
Noyce came to Shockley’s company in 1956.
The “Shockley Eight,” as they became known in the industry,
soon found themselves at odds with their boss over issues of research
and development. Seven of the dissenting scientists negotiated
with industrialist Sherman Fairchild, and they convinced the
remaining holdout, Noyce, to join them as their leader. The Shock-
Despite their tiny size, individual computer chips contain the basic logic circuits of entire
computers. (PhotoDisc)

Jack St. Clair Kilby
Computer chips / 231
Maybe the original, deepest inspiration for the integrated
circuit chip was topographical: As a boy Jack Kilby (b.1923) often
accompanied his father, an electrical engineer, on trips over
the circuit of roads through his flat home state, Kansas.
In any case, he learned to love things electrical, and radios
especially, from his father. Young Kilby had just started studying
at the University of Illinois on his way to a degree in electrical
engineering, when World War II started. He joined the
Office of Strategic Services (OSS), which sent him into Japaneseoccupied
territory to train local freedom fighters. He found the
radios given to him to be heavy and unreliable, so he got hold of
components on his own and built better, smaller radios.
The “better, smaller” theme stayed with him. His first job
out of college was with Centralab in Milwaukee, Wisconsin,
where he designed ever smaller circuits. However, the bulky,
hot vacuum tubes then in use limited miniaturization. In 1952,
Centralab and Kilby eagerly incorporated the newly invented
transistors into their designs. Kilby found, however, that all the
electrical connections needed to hook up transistors and wires
in a complex circuit also limited miniaturization.
He moved to Texas Instruments in 1958. The company was
working on a modular approach to miniaturization with snaptogether
standardized parts. Kilby had a better idea: place everything
for a specific circuit on a chip of silicon. Along with
many other inventors, Kilby was soon looking for ways to put
this new integrated circuit to work. He experimented with their
use in computers and in generating solar power. He helped to
develop the first hand-held calculator. Soon integrated circuits
were in practically every electronic gadget, so that by the year
2000 his invention supported an electronic equipment industry
that earned more than a trillion dollars a year.
Among his many awards, Kilby shared the 2000 Nobel Prize
in Physics with Zhores I. Alferov and Herbert Kroemer, both of
whom also miniaturized electronics.
ley Eight defected in 1957 to form a new company, Fairchild Semiconductor,
in nearby Mountain View, California. Shockley’s company,
which never recovered from the loss of these scientists, soon
went out of business.

232 / Computer chips
Integrating Circuits
Research efforts at Fairchild Semiconductor and Texas Instruments,
in Dallas, Texas, focused on putting several transistors on
one piece, or “chip,” of silicon. The first step involved making miniaturized
electrical circuits. Jack St. Clair Kilby, a researcher at Texas
Instruments, succeeded in making a circuit on a chip that consisted
of tiny resistors, transistors, and capacitors, all of which were connected
with gold wires. He and his company filed for a patent on
this “integrated circuit” in February, 1959. Noyce and his associates
at Fairchild Semiconductor followed in July of that year with an integrated
circuit manufactured by means of a “planar process,”
which involved laying down several layers of semiconductor that
were isolated by layers of insulating material. Although Kilby and
Noyce are generally recognized as coinventors of the integrated circuit,
Kilby alone received a membership in the National Inventors
Hall of Fame for his efforts.
Consequences
By 1968, Fairchild Semiconductor had grown to a point at which
many of its key Silicon Valley managers had major philosophical
differences with the East Coast management of their parent company.
This led to a major exodus of top-level management and engineers.
Many started their own companies. Noyce, Gordon E. Moore,
and Andrew Grove left Fairchild to form a new company in Santa
Clara called Intel with $2 million that had been provided by venture
capitalist Arthur Rock. Intel’s main business was the manufacture
of computer memory integrated circuit chips. By 1970, Intel was
able to develop and bring to market a random-access memory
(RAM) chip that was subsequently purchased in large quantities by
several major computer manufacturers, providing large profits for
Intel.
In 1969, Marcian Edward Hoff, Jr., an Intel research and development
engineer, met with engineers from Busicom, a Japanese firm.
These engineers wanted Intel to design a set of integrated circuits for
Busicom’s desktop calculators, but Hoff told them their specifications
were too complex. Nevertheless, Hoff began to think about the possi-

Circuitry of a typical computer chip. (PhotoDisc)
Computer chips / 233
bility of incorporating all the logic circuits of a computer central processing
unit (CPU) into one chip. He began to design a chip called a
“microprocessor,” which, when combined with a chip that would
hold a program and one that would hold data, would become a small,
general-purpose computer. Noyce encouraged Hoff and his associates
to continue his work on the microprocessor, and Busicom contracted
with Intel to produce the chip. Frederico Faggin, who was hired from
Fairchild, did the chip layout and circuit drawings.
In January, 1971, the Intel team finished its first working microprocessor,
the 4004. The following year, Intel made a higher-capacity
microprocessor, the 8008, for Computer Terminals Corporation.
That company contracted with Texas Instruments to produce a chip
with the same specifications as the 8008, which was produced in
June, 1972. Other manufacturers soon produced their own microprocessors.
The Intel microprocessor became the most widely used computer
chip in the budding personal computer industry and may
take significant credit for the PC “revolution” that soon followed.
Microprocessors have become so common that people use them every
day without realizing it. In addition to being used in computers,

234 / Computer chips
the microprocessor has found its way into automobiles, microwave
ovens, wristwatches, telephones, and many other ordinary items.
See also Bubble memory; Floppy disk; Hard disk; Optical disk;
Personal computer; Virtual machine.
Further Reading
Ceruzzi, Paul E. A History of Modern Computing. Cambridge, Mass.:
MIT Press, 2000.
Reid, T. R. The Chip: How Two Americans Invented the Microchip and
Launched a Revolution. New York: Random House, 2001.
Slater, Robert. Portraits in Silicon. Cambridge, Mass.: MIT Press,
1987.

Contact lenses
Contact lenses
The invention: Small plastic devices that fit under the eyelids, contact
lenses, or “contacts,” frequently replace the more familiar
eyeglasses that many people wear to correct vision problems.
The people behind the invention:
Leonardo da Vinci (1452-1519), an Italian artist and scientist
Adolf Eugen Fick (1829-1901), a German glassblower
Kevin Tuohy, an American optician
Otto Wichterle (1913- ), a Czech chemist
William Feinbloom (1904-1985), an American optometrist
An Old Idea
235
There are two main types of contact lenses: hard and soft. Both
types are made of synthetic polymers (plastics). The basic concept of
the contact lens was conceived by Leonardo da Vinci in 1508. He
proposed that vision could be improved if small glass ampules
filled with water were placed in front of each eye. Nothing came of
the idea until glass scleral lenses were invented by the German
glassblower Adolf Fick. Fick’s large, heavy lenses covered the pupil
of the eye, its colored iris, and part of the sclera (the white of the
eye). Fick’s lenses were not useful, since they were painful to wear.
In the mid-1930’s, however, plastic scleral lenses were developed
by various organizations and people, including the German company
I. G. Farben and the American optometrist William Feinbloom.
These lenses were light and relatively comfortable; they
could be worn for several hours at a time.
In 1945, the American optician Kevin Tuohy developed corneal
lenses, which covered only the cornea of the eye. Reportedly,
Tuohy’s invention was inspired by the fact that his nearsighted wife
could not bear scleral lenses but hated to wear eyeglasses. Tuohy’s
lenses were hard contact lenses made of rigid plastic, but they were
much more comfortable than scleral lenses and could be worn for
longer periods of time. Soon after, other people developed soft contact
lenses, which cover both the cornea and the iris. At present,

236 / Contact lenses
many kinds of contact lenses are available. Both hard and soft contact
lenses have advantages for particular uses.
Eyes, Tears, and Contact Lenses
The camera-like human eye automatically focuses itself and adjusts
to the prevailing light intensity. In addition, it never runs out of
“film” and makes a continuous series of visual images. In the process
of seeing, light enters the eye and passes through the clear,
dome-shaped cornea, through the hole (the pupil) in the colored
iris, and through the clear eye lens, which can change shape by
means of muscle contraction. The lens focuses the light, which next
passes across the jellylike “vitreous humor” and hits the retina.
There, light-sensitive retinal cells send visual images to the optic
nerve, which transmits them to the brain for interpretation.
Many people have 20/20 (normal) vision, which means that they
can clearly see letters on a designated line of a standard eye chart
placed 20 feet away. Nearsighted (myopic) people have vision of
20/40 or worse. This means that, 20 feet from the eye chart, they see
clearly what people with 20/20 vision can see clearly at a greater
distance.
Myopia (nearsightedness) is one of the four most common visual
defects. The others are hyperopia, astigmatism, and presbyopia. All
are called “refractive errors” and are corrected with appropriate
eyeglasses or contact lenses. Myopia, which occurs in 30 percent of
humans, occurs when the eyeball is too long for the lens’s focusing
ability and images of distant objects focus before they reach the retina,
causing blurry vision. Hyperopia, or farsightedness, occurs
when the eyeballs are too short. In hyperopia, the eye’s lenses cannot
focus images of nearby objects by the time those images reach
the retina, resulting in blurry vision. A more common condition is
astigmatism, in which incorrectly shaped corneas make all objects
appear blurred. Finally, presbyopia, part of the aging process,
causes the lens of the eye to lose its elasticity. It causes progressive
difficulty in seeing nearby objects. In myopic, hyperopic, or astigmatic
people, bifocal (two-lens) systems are used to correct presbyopia,
whereas monofocal systems are used to correct presbyopia in
people whose vision is otherwise normal.

William Feinbloom
Contact lenses / 237
William Feinbloom started his career in eye care when he
was only three, helping his father, an optometrist, in his practice.
Born in Brooklyn, New York, in 1904, Feinbloom studied at
the Columbia School of Optometry and graduated at nineteen.
He later earned degrees in physics, mathematics, biophysics,
and psychology, all of it to help him treat people who suffered
visual impairments. His many achievements on the behalf of
the partially sighted won him professional accolades as the “father
of low vision.”
In 1932, while working in a clinic, Feinbloom produced the
first of his special vision-enhancing inventions. He ground
three-power lenses, imitating the primary lens of a refracting
telescope, and fit them in a frame for an elderly patient whose
vision could not be treated. The patient was again able to see,
and when news of this miracle later reached Pope Pius XI, he
sent a special blessing to Feinbloom. He soon opened his own
practice and during the next fifty years invented a series of new
lenses for people with macular degeneration and other vision
diseases, as well as making the first set of contact lenses in
America.
In 1978 Feinbloom bequeathed his practice to the Pennsylvania
College of Optometry, which named it the William Feinbloom
Vision Rehabilitation Center. Every year the William
Feinbloom Award honors a vision-care specialist who has improved
the delivery and quality of optometric service. Feinbloom
died in 1985.
Modern contact lenses, which many people prefer to eyeglasses,
are used to correct all common eye defects as well as many others
not mentioned here. The lenses float on the layer of tears that is
made continuously to nourish the eye and keep it moist. They fit under
the eyelids and either over the cornea or over both the cornea
and the iris, and they correct visual errors by altering the eye’s focal
length enough to produce 20/20 vision. In addition to being more attractive
than eyeglasses, contact lenses correct visual defects more effectively
than eyeglasses can. Some soft contact lenses (all are made
of flexible plastics) can be worn almost continuously. Hard lenses are

238 / Contact lenses
made of more rigid plastic and last longer, though they can usually be
worn only for six to nine hours at a time. The choice of hard or soft
lenses must be made on an individual basis.
The disadvantages of contact lenses include the fact that they must
be cleaned frequently to prevent eye irritation. Furthermore, people
who do not produce adequate amounts of tears (a condition called
“dry eyes”) cannot wear them. Also, arthritis, many allergies, and
poor manual dexterity caused by old age or physical problems make
many people poor candidates for contact lenses.
Impact
The invention of Plexiglas hard scleral contact lenses set the stage
for the development of the widely used corneal hard lenses by Tuohy.
The development of soft contact lenses available to the general public
began in Czechoslovakia in the 1960’s. It led to the sale, starting in the
1970’s, of the popular, soft
contact lenses pioneered by
Otto Wichterle. The Wichterle
lenses, which cover
both the cornea and the iris,
are made of a plastic called
HEMA (short for hydroxyethylmethylmethacrylate).
These very thin lenses
have disadvantages that include
the requirement of
disinfection between uses,
incomplete astigmatism correction,
low durability, and
the possibility of chemical
combination with some
medications, which can
damage the eyes. Therefore,
much research is being
carried out to improve
Contact lenses are placed directly on the surface of
the eye. (Digital Stock)
them. For this reason, and
because of the continued

popularity of hard lenses, new kinds of soft and hard lenses are continually
coming on the market.
See also Artificial heart; Disposable razor; Hearing aid; Laser eye
surgery; Pacemaker.
Further Reading
Contact lenses / 239
“The Contact Lens.” Newsweek 130 (Winter, 1997/1998).
Hemphill, Clara. “A Quest for Better Vision: Spectacles over the
Centuries.” New York Times (August 8, 2000).
Koetting, Robert A. History of the Contact Lens. Irvine, Calif.:
Allergan, 1978.
Lubick, Naomi. “The Hard and the Soft.” Scientific American 283, no.
4 (October, 2000).

240
Coronary artery bypass surgery
Coronary artery bypass surgery
The invention: The most widely used procedure of its type, coronary
bypass surgery uses veins from legs to improve circulation
to the heart.
The people behind the invention:
Rene Favaloro (1923-2000), a heart surgeon
Donald B. Effler (1915- ), a member of the surgical team
that performed the first coronary artery bypass operation
F. Mason Sones (1918- ), a physician who developed an
improved technique of X-raying the heart’s arteries
Fighting Heart Disease
In the mid-1960’s, the leading cause of death in the United States
was coronary artery disease, claiming nearly 250 deaths per 100,000
people. Because this number was so alarming, much research was
being conducted on the heart. Most of the public’s attention was focused
on heart transplants performed separately by the famous surgeons
Christiaan Barnard and Michael DeBakey. Yet other, less dramatic
procedures were being developed and studied.
A major problem with coronary artery disease, besides the threat
of death, is chest pain, or angina. Individuals whose arteries are
clogged with fat and cholesterol are frequently unable to deliver
enough oxygen to their heart muscles. This may result in angina,
which causes enough pain to limit their physical activities. Some of
the heart research in the mid-1960’s was an attempt to find a surgical
procedure that would eliminate angina in heart patients. The
various surgical procedures had varying success rates.
In the late 1950’s and early 1960’s, a team of physicians in Cleveland
was studying surgical procedures that would eliminate angina.
The team was composed of Rene Favaloro, Donald B. Effler, F.
Mason Sones, and Laurence Groves. They were working on the concept,
proposed by Dr. Arthur M. Vineberg from McGill University
in Montreal, of implanting a healthy artery from the chest into the
heart. This bypass procedure would provide the heart with another

Bypass
Graft
Blockage
Before bypass surgery (left) the blockage in the artery
threatens to cut off bloodflow; after surgery to
graft a piece of vein (right), the blood can flow
around the blockage.
Coronary artery bypass surgery / 241
source of blood, resulting
in enough oxygen to overcome
the angina. Yet Vineberg’s
surgery was often
ineffective because it was
hard to determine exactly
where to implant the new
artery.
New Techniques
In order to make Vineberg’s
proposed operation
successful, better diagnostic
tools were needed. This was
accomplished by the work
of Sones. He developed a diagnostic procedure, called “arteriography,”
whereby a catheter was inserted into an artery in the arm,
which he ran all the way into the heart. He then injected a dye into the
coronary arteries and photographed them with a high-speed motionpicture
camera. This provided an image of the heart, which made it
easy to determine where the blockages were in the coronary arteries.
Using this tool, the team tried several new techniques. First, the
surgeons tried to ream out the deposits found in the narrow portion
of the artery. They found, however, that this actually reduced
blood flow. Second, they tried slitting the length of the blocked
area of the artery and suturing a strip of tissue that would increase
the diameter of the opening. This was also ineffective because it often
resulted in turbulent blood flow. Finally, the team attempted to
reroute the flow of blood around the blockage by suturing in other
tissue, such as a portion of a vein from the upper leg. This bypass
procedure removed that part of the artery that was clogged and replaced
it with a clear vessel, thereby restoring blood flow through
the artery. This new method was introduced by Favaloro in 1967.
In order for Favaloro and other heart surgeons to perform coronary
artery surgery successfully, several other medical techniques
had to be developed. These included extracorporeal circulation and
microsurgical techniques.

242 / Coronary artery bypass surgery
Extracorporeal circulation is the process of diverting the patient’s
blood flow from the heart and into a heart-lung machine.
This procedure was developed in 1953 by U.S. surgeon John H.
Gibbon, Jr. Since the blood does not flow through the heart, the
heart can be temporarily stopped so that the surgeons can isolate
the artery and perform the surgery on motionless tissue.
Microsurgery is necessary because some of the coronary arteries
are less than 1.5 millimeters in diameter. Since these arteries
had to be sutured, optical magnification and very delicate and sophisticated
surgical tools were required. After performing this surgery
on numerous patients, follow-up studies were able to determine
the surgery’s effectiveness. Only then was the value of coronary artery
bypass surgery recognized as an effective procedure for reducing angina
in heart patients.
Consequences
According to the American Heart Association, approximately
332,000 bypass surgeries were performed in the United States in
1987, an increase of 48,000 from 1986. These figures show that the
work by Favaloro and others has had a major impact on the
health of United States citizens. The future outlook is also positive.
It has been estimated that five million people had coronary
artery disease in 1987. Of this group, an estimated 1.5 million had
heart attacks and 500,000 died. Of those living, many experienced
angina. Research has developed new surgical procedures and
new drugs to help fight coronary artery disease. Yet coronary artery
bypass surgery is still a major form of treatment.
See also Artificial blood; Artificial heart; Blood transfusion;
Electrocardiogram; Heart-lung machine; Pacemaker.
Further Reading
Bing, Richard J. Cardiology: The Evolution of the Science and the
Art. 2d ed. New Brunswick, N.J.: Rutgers University Press,
1999.

Coronary artery bypass surgery / 243
Faiola, Anthony. “Doctor’s Suicide Strikes at Heart of Argentina’s
Health Care Crisis: Famed Cardiac Surgeon Championed
the Poor.” Washington Post (August 25, 2000).
Favaloro, René G. The Challenging Dream of Heart Surgery: From the
Pampas to Cleveland. Boston: Little, Brown, 1994.

244
Cruise missile
Cruise missile
The invention: Aircraft weapons system that makes it possible to
attack both land and sea targets with extreme accuracy without
endangering the lives of the pilots.
The person behind the invention:
Rear Admiral Walter M. Locke (1930- ), U.S. Navy project
manager
From the Buzz Bombs of World War II
During World War II, Germany developed and used two different
types of missiles: ballistic missiles and cruise missiles. A ballistic
missile is one that does not use aerodynamic lift in order to fly. It is
fired into the air by powerful jet engines and reaches a high altitude;
when its engines are out of fuel, it descends on its flight path toward
its target. The German V-2 was the first ballistic missile. The United
States and other countries subsequently developed a variety of
highly sophisticated and accurate ballistic missiles.
The other missile used by Germany was a cruise missile called
the V-1, which was also called the flying bomb or the buzz bomb.
The V-1 used aerodynamic lift in order to fly, just as airplanes do. It
flew relatively low and was slow; by the end of the war, the British,
against whom it was used, had developed techniques for countering
it, primarily by shooting it down.
After World War II, both the United States and the Soviet Union
carried on the Germans’ development of both ballistic and cruise
missiles. The United States discontinued serious work on cruise
missile technology during the 1950’s: The development of ballistic
missiles of great destructive capability had been very successful.
Ballistic missiles armed with nuclear warheads had become the basis
for the U.S. strategy of attempting to deter enemy attacks with
the threat of a massive missile counterattack. In addition, aircraft
carriers provided an air-attack capability similar to that of cruise
missiles. Finally, cruise missiles were believed to be too vulnerable
to being shot down by enemy aircraft or surface-to-air missiles.

While ballistic missiles are excellent for attacking large, fixed targets,
they are not suitable for attacking moving targets. They can be
very accurately aimed, but since they are not very maneuverable
during their final descent, they are limited in their ability to change
course to hit a moving target, such as a ship.
During the 1967 war, the Egyptians used a Soviet-built cruise
missile to sink the Israeli ship Elath. The U.S. military, primarily the
Navy and the Air Force, took note of the Egyptian success and
within a few years initiated cruise missile development programs.
The Development of Cruise Missiles
Cruise missile / 245
The United States probably could have developed cruise missiles
similar to 1990’s models as early as the 1960’s, but it would have required
a huge effort. The goal was to develop missiles that could be
launched from ships and planes using existing launching equipment,
could fly long distances at low altitudes at fairly high speeds,
and could reach their targets with a very high degree of accuracy. If
the missiles flew too slowly, they would be fairly easy to shoot
down, like the German V-1’s. If they flew at too high an altitude,
they would be vulnerable to the same type of surface-based missiles
that shot down Gary Powers, the pilot of the U.S. U2 spyplane, in
1960. If they were inaccurate, they would be of little use.
The early Soviet cruise missiles were designed to meet their performance
goals without too much concern about how they would
be launched. They were fairly large, and the ships that launched
them required major modifications. The U.S. goal of being able to
launch using existing equipment, without making major modifications
to the ships and planes that would launch them, played a major
part in their torpedo-like shape: Sea-Launched Cruise Missiles
(SLCMs) had to fit in the submarine’s torpedo tubes, and Air-
Launched Cruise Missiles (ALCMs) were constrained to fit in rotary
launchers. The size limitation also meant that small, efficient jet engines
would be required that could fly the long distances required
without needing too great a fuel load. Small, smart computers were
needed to provide the required accuracy. The engine and computer
technologies began to be available in the 1970’s, and they blossomed
in the 1980’s.

246 / Cruise missile
The U.S. Navy initiated cruise missile development efforts in
1972; the Air Force followed in 1973. In 1977, the Joint Cruise Missile
Project was established, with the Navy taking the lead. Rear
Admiral Walter M. Locke was named project manager. The goal
was to develop air-, sea-, and ground-launched cruise missiles.
By coordinating activities, encouraging competition, and
requiring the use of common components wherever possible, the
cruise missile development program became a model for future
weapon-system development efforts. The primary contractors
included Boeing Aerospace Company, General Dynamics, and
McDonnell Douglas.
In 1978, SLCMs were first launched from submarines. Over the
next few years, increasingly demanding tests were passed by several
versions of cruise missiles. By the mid-1980’s, both antiship and
antiland missiles were available. An antiland version could be guided
to its target with extreme accuracy by comparing a map programmed
into its computer to the picture taken by an on-board video camera.
The typical cruise missile is between 18 and 21 feet long, about 21
inches in diameter, and has a wingspan of between 8 and 12 feet.
Cruise missiles travel slightly below the speed of sound and have a
range of around 1,350 miles (antiland) or 250 miles (antiship). Both
conventionally armed and nuclear versions have been fielded.
Consequences
Cruise missiles have become an important part of the U.S. arsenal.
They provide a means of attacking targets on land and water
without having to put an aircraft pilot’s life in danger. Their value
was demonstrated in 1991 during the Persian Gulf War. One of their
uses was to “soften up” defenses prior to sending in aircraft, thus reducing
the risk to pilots. Overall estimates are that about 85 percent
of cruise missiles used in the Persian Gulf War arrived on target,
which is an outstanding record. It is believed that their extreme accuracy
also helped to minimize noncombatant casualties.
See also Airplane; Atomic bomb; Hydrogen bomb; Rocket;
Stealth aircraft; V-2 rocket.

Further Reading
Cruise missile / 247
Collyer, David G. Buzz Bomb. Deal, Kent, England: Kent Aviation
Historical Research Society, 1994.
McDaid, Hugh, and David Oliver. Robot Warriors: The Top Secret History
of the Pilotless Plane. London: Orion Media, 1997.
Macknight, Nigel. Tomahawk Cruise Missile. Osceola, Wis.: Motorbooks
International, 1995.
Werrell, Kenneth P. The Evolution of the Cruise Missile. Maxwell Air
Force Base, Ala.: Air University Press, 1997.

248
Cyclamate
Cyclamate
The invention: An artificial sweetener introduced to the American
market in 1950 under the tradename Sucaryl.
The person behind the invention:
Michael Sveda (1912-1999), an American chemist
A Foolhardy Experiment
The first synthetic sugar substitute, saccharin, was developed in
1879. It became commercially available in 1907 but was banned for
safety reasons in 1912. Sugar shortages during World War I (1914-
1918) resulted in its reintroduction. Two other artificial sweeteners,
Dulcin and P-4000, were introduced later but were banned in 1950
for causing cancer in laboratory animals.
In 1937, Michael Sveda was a young chemist working on his
Ph.D. at the University of Illinois. A flood in the Ohio valley had ruined
the local pipe-tobacco crop, and Sveda, a smoker, had been
forced to purchase cigarettes. One day while in the laboratory,
Sveda happened to brush some loose tobacco from his lips and noticed
that his fingers tasted sweet. Having a curious, if rather foolhardy,
nature, Sveda tasted the chemicals on his bench to find which
one was responsible for the taste. The culprit was the forerunner of
cyclohexylsulfamate, the material that came to be known as “cyclamate.”
Later, on reviewing his career, Sveda explained the serendipitous
discovery with the comment: “God looks after ...fools, children,
and chemists.”
Sveda joined E. I. Du Pont de Nemours and Company in 1939
and assigned the patent for cyclamate to his employer. In June of
1950, after a decade of testing on animals and humans, Abbott Laboratories
announced that it was launching Sveda’s artificial sweetener
under the trade name Sucaryl. Du Pont followed with its
sweetener product, Cyclan. A Time magazine article in 1950 announced
the new product and noted that Abbott had warned that
because the product was a sodium salt, individuals with kidney
problems should consult their doctors before adding it to their food.

Cyclamate had no calories, but it was thirty to forty times sweeter
than sugar. Unlike saccharin, cyclamate left no unpleasant aftertaste.
The additive was also found to improve the flavor of some
foods, such as meat, and was used extensively to preserve various
foods. By 1969, about 250 food products contained cyclamates, including
cakes, puddings, canned fruit, ice cream, salad dressings,
and its most important use, carbonated beverages.
It was originally thought that cyclamates were harmless to the
human body. In 1959, the chemical was added to the GRAS (generally
recognized as safe) list. Materials on this list, such as sugar, salt,
pepper, and vinegar, did not have to be rigorously tested before being
added to food. In 1964, however, a report cited evidence that cyclamates
and saccharin, taken together, were a health hazard. Its
publication alarmed the scientific community. Numerous investigations
followed.
Shooting Themselves in the Foot
Cyclamate / 249
Initially, the claims against cyclamate had been that it caused diarrhea
or prevented drugs from doing their work in the body.
By 1969, these claims had begun to include the threat of cancer.
Ironically, the evidence that sealed the fate of the artificial sweetener
was provided by Abbott itself.
A private Long Island company had been hired by Abbott to conduct
an extensive toxicity study to determine the effects of longterm
exposure to the cyclamate-saccharin mixtures often found in
commercial products. The team of scientists fed rats daily doses of
the mixture to study the effect on reproduction, unborn fetuses, and
fertility. In each case, the rats were declared to be normal. When the
rats were killed at the end of the study, however, those that had been
exposed to the higher doses showed evidence of bladder tumors.
Abbott shared the report with investigators from the National Cancer
Institute and then with the U.S. Food and Drug Administration
(FDA).
The doses required to produce the tumors were equivalent to an
individual drinking 350 bottles of diet cola a day. That was more
than one hundred times greater than that consumed even by those
people who consumed a high amount of cyclamate. A six-person

250 / Cyclamate
panel of scientists met to review the data and urged the ban of all cyclamates
from foodstuffs. In October, 1969, amid enormous media
coverage, the federal government announced that cyclamates were
to be withdrawn from the market by the beginning of 1970.
In the years following the ban, the controversy continued. Doubt
was cast on the results of the independent study linking sweetener
use to tumors in rats, because the study was designed not to evaluate
cancer risks but to explain the effects of cyclamate use over
many years. Bladder parasites, known as “nematodes,” found in the
rats may have affected the outcome of the tests. In addition, an impurity
found in some of the saccharin used in the study may have
led to the problems observed. Extensive investigations such as the
three-year project conducted at the National Cancer Research Center
in Heidelberg, Germany, found no basis for the widespread ban.
In 1972, however, rats fed high doses of saccharin alone were
found to have developed bladder tumors. At that time, the sweetener
was removed from the GRAS list. An outright ban was averted
by the mandatory use of labels alerting consumers that certain
products contained saccharin.
Impact
The introduction of cyclamate heralded the start of a new industry.
For individuals who had to restrict their sugar intake for health
reasons, or for those who wished to lose weight, there was now an
alternative to giving up sweet food.
The Pepsi-Cola company put a new diet drink formulation on
the market almost as soon as the ban was instituted. In fact, it ran
advertisements the day after the ban was announced showing the
Diet Pepsi product boldly proclaiming “Sugar added—No Cyclamates.”
Sveda, the discoverer of cyclamates, was not impressed with the
FDA’s decision on the sweetener and its handling of subsequent investigations.
He accused the FDA of “a massive cover-up of elemental
blunders” and claimed that the original ban was based on sugar
politics and bad science.
For the manufacturers of cyclamate, meanwhile, the problem lay
with the wording of the Delaney amendment, the legislation that

egulates new food additives. The amendment states that the manufacturer
must prove that its product is safe, rather than the FDAhaving
to prove that it is unsafe. The onus was on Abbott Laboratories
to deflect concerns about the safety of the product, and it remained
unable to do so.
See also Aspartame; Genetically engineered insulin.
Further Reading
Cyclamate / 251
Kaufman, Leslie. “Michael Sveda, the Inventor of Cyclamates, Dies
at Eighty Seven.” New York Times (August 21, 1999).
Lawler, Philip F. Sweet Talk: Media Coverage of Artificial Sweeteners.
Washington, D.C.: Media Institute, 1986.
Remington, Dennis W. The Bitter Truth About Artificial Sweeteners.
Provo, Utah: Vitality House, 1987.
Whelan, Elizabeth M. “The Bitter Truth About a Sweetener Scare.”
Wall Street Journal (August 26, 1999).

252
Cyclotron
Cyclotron
The invention: The first successful magnetic resonance accelerator
for protons, the cyclotron gave rise to the modern era of particle
accelerators, which are used by physicists to study the structure
of atoms.
The people behind the invention:
Ernest Orlando Lawrence (1901-1958), an American nuclear
physicist who was awarded the 1939 Nobel Prize in Physics
M. Stanley Livingston (1905-1986), an American nuclear
physicist
Niels Edlefsen (1893-1971), an American physicist
David Sloan (1905- ), an American physicist and electrical
engineer
The Beginning of an Era
The invention of the cyclotron by Ernest Orlando Lawrence
marks the beginning of the modern era of high-energy physics. Although
the energies of newer accelerators have increased steadily,
the principles incorporated in the cyclotron have been fundamental
to succeeding generations of accelerators, many of which were also
developed in Lawrence’s laboratory. The care and support for such
machines have also given rise to “big science”: the massing of scientists,
money, and machines in support of experiments to discover
the nature of the atom and its constituents.
At the University of California, Lawrence took an interest in the
new physics of the atomic nucleus, which had been developed by
the British physicist Ernest Rutherford and his followers in England,
and which was attracting more attention as the development
of quantum mechanics seemed to offer solutions to problems that
had long preoccupied physicists. In order to explore the nucleus of
the atom, however, suitable probes were required. An artificial
means of accelerating ions to high energies was also needed.
During the late 1920’s, various means of accelerating alpha particles,
protons (hydrogen ions), and electrons had been tried, but

none had been successful in causing a nuclear transformation when
Lawrence entered the field. The high voltages required exceeded
the resources available to physicists. It was believed that more than
a million volts would be required to accelerate an ion to sufficient
energies to penetrate even the lightest atomic nuclei. At such voltages,
insulators broke down, releasing sparks across great distances.
European researchers even attempted to harness lightning to accomplish
the task, with fatal results.
Early in April, 1929, Lawrence discovered an article by a German
electrical engineer that described a linear accelerator of ions that
worked by passing an ion through two sets of electrodes, each of
which carried the same voltage and increased the energy of the ions
correspondingly. By spacing the electrodes appropriately and using
an alternating electrical field, this “resonance acceleration” of ions
could speed subatomic particles to many times the energy applied
in each step, overcoming the problems presented when one tried to
apply a single charge to an ion all at once. Unfortunately, the spacing
of the electrodes would have to be increased as the ions were accelerated,
since they would travel farther between each alternation
of the phase of the accelerating charge, making an accelerator impractically
long in those days of small-scale physics.
Fast-Moving Streams of Ions
Cyclotron / 253
Lawrence knew that a magnetic field would cause the ions to be
deflected and form a curved path. If the electrodes were placed
across the diameter of the circle formed by the ions’ path, they
should spiral out as they were accelerated, staying in phase with the
accelerating charge until they reached the periphery of the magnetic
field. This, it seemed to him, afforded a means of producing indefinitely
high voltages without using high voltages by recycling the accelerated
ions through the same electrodes. Many scientists doubted
that such a method would be effective. No mechanism was known
that would keep the circulating ions in sufficiently tight orbits to
avoid collisions with the walls of the accelerating chamber. Others
tried unsuccessfully to use resonance acceleration.
A graduate student, M. Stanley Livingston, continued Lawrence’s
work. For his dissertation project, he used a brass cylinder 10 centi-

254 / Cyclotron
Ernest Orlando Lawrence
A man of great energy and gusty temper, Ernest Orlando
Lawrence danced for joy when one of his cyclotrons accelerated
a particle to more than the one million electron volts. That
amount of power was important, according to contemporary
theorists, because it was enough to penetrate the nucleus of a
target atom. For giving physicists a tool with which to examine
the subatomic realm, Lawrence received the 1939 Nobel Prize in
Physics, among many other honors.
The grandson of Norwegian immigrants, Lawrence was
born in Canton, South Dakota, in 1901. After high school, he
went to St. Olaf’s College, the University of South Dakota, the
University of Minnesota, and Yale University, where he completed
a doctorate in physics in 1925. After post-graduate fellowships
at Yale, he became a professor at the University of
California, Berkeley, the youngest on campus. In 1936 the university
made him director of its radiation laboratory. Now
named the Lawrence-Livermore National Laboratory, it stayed
at the forefront of physics and high-technology research ever
since.
Before World War II Lawrence and his brother, Dr. John
Lawrence, also at the university, worked together to find practical
biological and medical applications for the radioisotopes
made in Lawrence’s particle accelerators. During the war Lawrence
participated in the Manhattan Project, which made the
atomic bomb. He was a passionate anticommunist and after the
war argued before Congress for funds to develop death rays
and radiation bombs from research with his cyclotrons; however,
he was also an American delegate to the Geneva Conference
in 1958, which sought a ban on atomic bomb tests.
Lawrence helped solve the mystery of cosmic particles, invented
a method for measuring ultra-small time intervals, and
calculated with high precision the ratio of the charge of an electron
to its mass, a fundamental constant of nature. Lawrence
died in 1958 in Palo Alto, California.
meters in diameter sealed with wax to hold a vacuum, a half-pillbox
of copper mounted on an insulated stem to serve as the electrode,
and a Hartley radio frequency oscillator producing 10 watts. The
hydrogen molecular ions were produced by a thermionic cathode

(mounted near the center of the apparatus) from hydrogen gas admitted
through an aperture in the side of the cylinder after a vacuum
had been produced by a pump. Once formed, the oscillating
electrical field drew out the ions and accelerated them as they
passed through the cylinder. The accelerated ions spiraled out in a
magnetic field produced by a 10-centimeter electromagnet to a collector.
By November, 1930, Livingston had observed peaks in the
collector current as he tuned the magnetic field through the value
calculated to produce acceleration.
Borrowing a stronger magnet and tuning his radio frequency oscillator
appropriately, Livingston produced 80,000-electronvolt ions
at his collector on January 2, 1931, thus demonstrating the principle
of magnetic resonance acceleration.
Impact
Cyclotron / 255
Demonstration of the principle led to the construction of a succession
of large cyclotrons, beginning with a 25-centimeter cyclotron
developed in the spring and summer of 1931 that produced
one-million-electronvolt protons. With the support of the Research
Corporation, Lawrence secured a large electromagnet that had been
developed for radio transmission and an unused laboratory to
house it: the Radiation Laboratory.
The 69-centimeter cyclotron built with the magnet was used to
explore nuclear physics. It accelerated deuterons, ions of heavy
water or deuterium that contain, in addition to the proton, the neutron,
which was discovered by Sir James Chadwick in 1932. The accelerated
deuteron, which injected neutrons into target atoms, was
used to produce a wide variety of artificial radioisotopes. Many of
these, such as technetium and carbon 14, were discovered with the
cyclotron and were later used in medicine.
By 1939, Lawrence had built a 152-centimeter cyclotron for medical
applications, including therapy with neutron beams. In that
year, he won the Nobel Prize in Physics for the invention of the cyclotron
and the production of radioisotopes. During World War II,
Lawrence and the members of his Radiation Laboratory developed
electromagnetic separation of uranium ions to produce the uranium
235 required for the atomic bomb. After the war, the 467-centimeter

256 / Cyclotron
cyclotron was completed as a synchrocyclotron, which modulated
the frequency of the accelerating fields to compensate for the increasing
mass of ions as they approached the speed of light. The
principle of synchronous acceleration, invented by Lawrence’s associate,
the American physicist Edwin Mattison McMillan, became
fundamental to proton and electron synchrotrons.
The cyclotron and the Radiation Laboratory were the center of
accelerator physics throughout the 1930’s and well into the postwar
era. The invention of the cyclotron not only provided a new tool for
probing the nucleus but also gave rise to new forms of organizing
scientific work and to applications in nuclear medicine and nuclear
chemistry. Cyclotrons were built in many laboratories in the United
States, Europe, and Japan, and they became a standard tool of nuclear
physics.
See also Atomic bomb; Electron microscope; Field ion microscope;
Geiger counter; Hydrogen bomb; Mass spectrograph; Neutrino
detector; Scanning tunneling microscope; Synchrocyclotron;
Tevatron accelerator.
Further Reading
Childs, Herbert. An American Genius: The Life of Ernest Orlando Lawrence.
New York: Dutton, 1968.
Close, F. E., Michael Marten, and Christine Sutton. The Particle Explosion.
New York: Oxford University Press, 1994.
Pais, Abraham. Inward Bound: Of Matter and Forces in the Physical
World. New York: Clarendon Press, 1988.
Wilson, Elizabeth K. “Fifty Years of Heavy Chemistry.” Chemical and
Engineering News 78, no. 13 (March 27, 2000).

Diesel locomotive
Diesel locomotive
The invention: An internal combustion engine in which ignition is
achieved by the use of high-temperature compressed air, rather
than a spark plug.
The people behind the invention:
Rudolf Diesel (1858-1913), a German engineer and inventor
Sir Dugold Clark (1854-1932), a British engineer
Gottlieb Daimler (1834-1900), a German engineer
Henry Ford (1863-1947), an American automobile magnate
Nikolaus Otto (1832-1891), a German engineer and Daimler’s
teacher
A Beginning in Winterthur
257
By the beginning of the twentieth century, new means of providing
society with power were needed. The steam engines that were
used to run factories and railways were no longer sufficient, since
they were too heavy and inefficient. At that time, Rudolf Diesel, a
German mechanical engineer, invented a new engine. His diesel engine
was much more efficient than previous power sources. It also
appeared that it would be able to run on a wide variety of fuels,
ranging from oil to coal dust. Diesel first showed that his engine was
practical by building a diesel-driven locomotive that was tested in
1912.
In the 1912 test runs, the first diesel-powered locomotive was operated
on the track of the Winterthur-Romanston rail line in Switzerland.
The locomotive was built by a German company, Gesellschaft
für Thermo-Lokomotiven, which was owned by Diesel and
his colleagues. Immediately after the test runs at Winterthur proved
its efficiency, the locomotive—which had been designed to pull express
trains on Germany’s Berlin-Magdeburg rail line—was moved
to Berlin and put into service. It worked so well that many additional
diesel locomotives were built. In time, diesel engines were
also widely used to power many other machines, including those
that ran factories, motor vehicles, and ships.

258 / Diesel locomotive
Rudolf Diesel
Unbending, suspicious of others, but also exceptionally intelligent,
Rudolf Christian Karl Diesel led a troubled life and
came to a mysterious end. His parents, expatriate Germans,
lived in Paris when he was born, 1858, and he spent his early
childhood there. In 1870, just as he was starting his formal education,
his family fled to England on the outbreak of the Franco-
Prussian War, which turned the French against Germans. In England,
Diesel spent much of his spare time in museums, educating
himself. His father, a leather craftsman, was unable to support
his family, so as a teenager Diesel was packed off to
Augsburg, Germany, where he was largely on his own. Although
these experiences made him fluent in English, French,
and German, his was not a stable or happy childhood.
He threw himself into his studies, finishing his high school
education three years ahead of schedule, and entered the Technical
College of Munich, where he was the star student. Once,
during his school years, he saw a demonstration of a Chinese
firestick. The firestick was a tube with a plunger. When a small
piece of flammable material was put in one end and the plunger
pushed down rapidly toward it, the heat of the compressed air
in the tube ignited the material. The demonstration later inspired
Diesel to adapt the principle to an engine.
His was the first engine to run successfully with compressed
air fuel ignition, but it was not the first design. So although he
received the patent for the diesel engine, he had to fight challenges
in court from other inventors over licensing rights. He always
won, but the strain of litigation worsened his tendency to
stubborn self-reliance, and this led him into difficulties. The
first compression engines were unreliable and unwieldy, but
Diesel rebuffed all suggestions for modifications, requiring that
builders follow his original design. His attitude led to delays in
development of the engine and lost him financial support.
In 1913, while crossing the English Channel aboard a ship,
Diesel disappeared. His body was never found, and although
the authorities concluded that Diesel committed suicide, no one
knows what happened.

Diesels, Diesels Everywhere
Diesel locomotive / 259
In the 1890’s, the best engines available were steam engines that
were able to convert only 5 to 10 percent of input heat energy to useful
work. The burgeoning industrial society and a widespread network
of railroads needed better, more efficient engines to help businesses
make profits and to speed up the rate of transportation
available for moving both goods and people, since the maximum
speed was only about 48 kilometers per hour. In 1894, Rudolf Diesel,
then thirty-five years old, appeared in Augsburg, Germany, with a
new engine that he believed would demonstrate great efficiency.
The diesel engine demonstrated at Augsburg ran for only a
short time. It was, however, more efficient than other existing engines.
In addition, Diesel predicted that his engines would move
trains faster than could be done by existing engines and that they
would run on a wide variety of fuels. Experimentation proved the
truth of his claims; even the first working motive diesel engine (the
one used in the Winterthur test) was capable of pulling heavy
freight and passenger trains at maximum speeds of up to 160 kilometers
per hour.
By 1912, Diesel, a millionaire, saw the wide use of diesel locomotives
in Europe and the United States and the conversion of hundreds
of ships to diesel power. Rudolf Diesel’s role in the story ends
here, a result of his mysterious death in 1913—believed to be a suicide
by the authorities—while crossing the English Channel on the
steamer Dresden. Others involved in the continuing saga of diesel
engines were the Britisher Sir Dugold Clerk, who improved diesel
design, and the American Adolphus Busch (of beer-brewing fame),
who bought the North American rights to the diesel engine.
The diesel engine is related to automobile engines invented by
Nikolaus Otto and Gottlieb Daimler. The standard Otto-Daimler (or
Otto) engine was first widely commercialized by American auto
magnate Henry Ford. The diesel and Otto engines are internalcombustion
engines. This means that they do work when a fuel is
burned and causes a piston to move in a tight-fitting cylinder. In diesel
engines, unlike Otto engines, the fuel is not ignited by a spark
from a spark plug. Instead, ignition is accomplished by the use of
high-temperature compressed air.

260 / Diesel locomotive
In common “two-stroke” diesel engines, pioneered by Sir Dugold
Clerk, a starter causes the engine to make its first stroke. This
draws in air and compresses the air sufficiently to raise its temperature
to 900 to 1,000 degrees Fahrenheit. At this point, fuel (usually
oil) is sprayed into the cylinder, ignites, and causes the piston to
make its second, power-producing stroke. At the end of that stroke,
more air enters as waste gases leave the cylinder; air compression
occurs again; and the power-producing stroke repeats itself. This
process then occurs continuously, without restarting.
Impact
Intake Compression Power Exhaust
The four strokes of a diesel engine. (Robert Bosch Corporation)
Proof of the functionality of the first diesel locomotive set the
stage for the use of diesel engines to power many machines. Although
Rudolf Diesel did not live to see it, diesel engines were
widely used within fifteen years after his death. At first, their main
applications were in locomotives and ships. Then, because diesel
engines are more efficient and more powerful than Otto engines,
they were modified for use in cars, trucks, and buses.
At present, motor vehicle diesel engines are most often used in
buses and long-haul trucks. In contrast, diesel engines are not as
popular in automobiles as Otto engines, although European auto-

makers make much wider use of diesel engines than American
automakers do. Many enthusiasts, however, view diesel automobiles
as the wave of the future. This optimism is based on the durability
of the engine, its great power, and the wide range and economical
nature of the fuels that can be used to run it. The drawbacks
of diesels include the unpleasant odor and high pollutant content of
their emissions.
Modern diesel engines are widely used in farm and earth-moving
equipment, including balers, threshers, harvesters, bulldozers,rock
crushers, and road graders. Construction of the Alaskan oil pipeline
relied heavily on equipment driven by diesel engines. Diesel engines
are also commonly used in sawmills, breweries, coal mines,
and electric power plants.
Diesel’s brainchild has become a widely used power source, just
as he predicted. It is likely that the use of diesel engines will continue
and will expand, as the demands of energy conservation require
more efficient engines and as moves toward fuel diversification
require engines that can be used with various fuels.
See also Bullet train; Gas-electric car; Internal combustion engine.
Further Reading
Diesel locomotive / 261
Cummins, C. Lyle. Diesel’s Engine. Wilsonville, Oreg.: Carnot Press,
1993.
Diesel, Eugen. From Engines to Autos: Five Pioneers in Engine Development
and Their Contributions to the Automotive Industry. Chicago:
H. Regnery, 1960.
Nitske, Robert W., and Charles Morrow Wilson. Rudolf Diesel: Pioneer
of the Age of Power. Norman: University of Oklahoma Press,
1965.

262
Differential analyzer
Differential analyzer
The invention: An electromechanical device capable of solving differential
equations.
The people behind the invention:
Vannevar Bush (1890-1974), an American electrical engineer
Harold L. Hazen (1901-1980), an American electrical engineer
Electrical Engineering Problems Become More Complex
After World War I, electrical engineers encountered increasingly
difficult differential equations as they worked on vacuum-tube circuitry,
telephone lines, and, particularly, long-distance power transmission
lines. These calculations were lengthy and tedious. Two of
the many steps required to solve them were to draw a graph manually
and then to determine the area under the curve (essentially, accomplishing
the mathematical procedure called integration).
In 1925, Vannevar Bush, a faculty member in the Electrical Engineering
Department at the Massachusetts Institute of Technology
(MIT), suggested that one of his graduate students devise a machine
to determine the area under the curve. They first considered a mechanical
device but later decided to seek an electrical solution. Realizing
that a watt-hour meter such as that used to measure electricity
in most homes was very similar to the device they needed, Bush and
his student refined the meter and linked it to a pen that automatically
recorded the curve.
They called this machine the Product Integraph, and MIT students
began using it immediately. In 1927, Harold L. Hazen, another
MIT faculty member, modified it in order to solve the more complex
second-order differential equations (it originally solved only firstorder
equations).
The Differential Analyzer
The original Product Integraph had solved problems electrically,
and Hazen’s modification had added a mechanical integrator. Al-

Differential analyzer / 263
though the revised Product Integraph was useful in solving the
types of problems mentioned above, Bush thought the machine
could be improved by making it an entirely mechanical integrator,
rather than a hybrid electrical and mechanical device.
In late 1928, Bush received funding from MIT to develop an entirely
mechanical integrator, and he completed the resulting Differential
Analyzer in 1930. This machine consisted of numerous interconnected
shafts on a long, tablelike framework, with drawing
boards flanking one side and six wheel-and-disk integrators on the
other. Some of the drawing boards were configured to allow an operator
to trace a curve with a pen that was linked to the Analyzer,
thus providing input to the machine. The other drawing boards
were configured to receive output from the Analyzer via a pen that
drew a curve on paper fastened to the drawing board.
The wheel-and-disk integrator, which Hazen had first used in
the revised Product Integraph, was the key to the operation of the
Differential Analyzer. The rotational speed of the horizontal disk
was the input to the integrator, and it represented one of the variables
in the equation. The smaller wheel rolled on the top surface of
the disk, and its speed, which was different from that of the disk,
represented the integrator’s output. The distance from the wheel to
the center of the disk could be changed to accommodate the equation
being solved, and the resulting geometry caused the two shafts
to turn so that the output was the integral of the input. The integrators
were linked mechanically to other devices that could add, subtract,
multiply, and divide. Thus, the Differential Analyzer could
solve complex equations involving many different mathematical
operations. Because all the linkages and calculating devices were
mechanical, the Differential Analyzer actually acted out each calculation.
Computers of this type, which create an analogy to the physical
world, are called analog computers.
The Differential Analyzer fulfilled Bush’s expectations, and students
and researchers found it very useful. Although each different
problem required Bush’s team to set up a new series of mechanical
linkages, the researchers using the calculations viewed this as a minor
inconvenience. Students at MIT used the Differential Analyzer
in research for doctoral dissertations, master’s theses, and bachelor’s
theses. Other researchers worked on a wide range of problems

264 / Differential analyzer
Vannevar Bush
One of the most politically powerful scientists of the twentieth
century, Vannevar Bush was born in 1890 in Everett, Massachusetts.
He studied at Tufts College in Boston, not only earning
two degrees in engineering but also registering his first
patent while still an undergraduate. He worked for General
Electric Company briefly after college and then conducted research
on submarine detection for the U.S. Navy during World
War I.
After the war he became a professor of electrical power
transmission (and later dean of the engineering school) at the
Massachusetts Institute of Technology (MIT). He also acted as a
consultant for industry and started companies of his own, including
(with two others) Raytheon Corporation. While at MIT
he developed the Product Integraph and Differential Analyzer
to aid in solving problems related to electrical power transmission.
Starting in 1939, Bush became a key science administrator.
He was president of the Carnegie Foundation from 1939 until
1955, chaired the National Advisory Committee for Aeronautics
from 1939 until 1941, in 1940 was appointed chairman of the
President’s National Defense Research Committee, and from
1941 until 1946 was director of the Office of Scientific Research
and Development. This meant he was President Franklin Roosevelt’s
science adviser during World War II and oversaw wartime
military research, including involvement in the Manhattan
Project that build the first atomic bombs. After the war he
worked for peaceful application of atomic power and was instrumental
in inaugurating the National Science Foundation,
which he directed, in 1950. Between 1957 and 1959 he served as
chairman of MIT Corporation, retaining an honorary chairmanship
thereafter.
All these political and administrative roles meant he exercised
enormous influence in deciding which scientific projects
were supported financially. Having received many honorary
degrees and awards, including the National Medal of Science
(1964), Bush died in 1974.

with the Differential Analyzer, mostly in electrical engineering, but
also in atomic physics, astrophysics, and seismology. An English researcher,
Douglas Hartree, visited Bush’s laboratory in 1933 to learn
about the Differential Analyzer and to use it in his own work on the
atomic field of mercury. When he returned to England, he built several
analyzers based on his knowledge of MIT’s machine. The U.S.
Army also built a copy in order to carry out the complex calculations
required to create artillery firing tables (which specified the
proper barrel angle to achieve the desired range). Other analyzers
were built by industry and universities around the world.
Impact
Differential analyzer / 265
As successful as the Differential Analyzer had been, Bush wanted
to make another, better analyzer that would be more precise, more
convenient to use, and more mathematically flexible. In 1932, Bush
began seeking money for his new machine, but because of the Depression
it was not until 1936 that he received adequate funding for
the Rockefeller Analyzer, as it came to be known. Bush left MIT in
1938, but work on the Rockefeller Analyzer continued. It was first
demonstrated in 1941, and by 1942, it was being used in the war effort
to calculate firing tables and design radar antenna profiles. At
the end of the war, it was the most important computer in existence.
All the analyzers, which were mechanical computers, faced serious
limitations in speed because of the momentum of the machinery,
and in precision because of slippage and wear. The digital computers
that were being developed after World War II (even at MIT)
were faster, more precise, and capable of executing more powerful
operations because they were electrical computers. As a result, during
the 1950’s, they eclipsed differential analyzers such as those
built by Bush. Descendants of the Differential Analyzer remained in
use as late as the 1990’s, but they played only a minor role.
See also Colossus computer; ENIAC computer; Mark I calculator;
Personal computer; SAINT; UNIVAC computer.

266 / Differential analyzer
Further Reading
Bush, Vannevar. Pieces of the Action. New York: Morrow, 1970.
Marcus, Alan I., and Howard P. Segal. Technology in America. Fort
Worth, Tex.: Harcourt Brace College, 1999.
Spencer, Donald D. Great Men and Women of Computing. Ormond
Beach, Fla.: Camelot Publishing, 1999.
Zachary, G. Pascal. Endless Frontier: Vannevar Bush, Engineer of the
American Century. Cambridge, Mass.: MIT Press, 1999.

Dirigible
Dirigible
The invention: A rigid lighter-than-air aircraft that played a major
role in World War I and in international air traffic until a disastrous
accident destroyed the industry.
The people behind the invention:
Ferdinand von Zeppelin (1838-1917), a retired German general
Theodor Kober (1865-1930), Zeppelin’s private engineer
Early Competition
267
When the Montgolfier brothers launched the first hot-air balloon
in 1783, engineers—especially those in France—began working on
ways to use machines to control the speed and direction of balloons.
They thought of everything: rowing through the air with silk-covered
oars; building movable wings; using a rotating fan, an airscrew, or a
propeller powered by a steam engine (1852) or an electric motor
(1882). At the end of the nineteenth century, the internal combustion
engine was invented. It promised higher speeds and more power.
Up to this point, however, the balloons were not rigid.
A rigid airship could be much larger than a balloon and could fly
farther. In 1890, a rigid airship designed by David Schwarz of
Dalmatia was tested in St. Petersburg, Russia. The test failed because
there were problems with inflating the dirigible. A second
test, in Berlin in 1897, was only slightly more successful, since the
hull leaked and the flight ended in a crash.
Schwarz’s airship was made of an entirely rigid aluminum cylinder.
Ferdinand von Zeppelin had a different idea: His design was
based on a rigid frame. Zeppelin knew about balloons from having
fought in two wars in which they were used: the American Civil
War of 1861-1865 and the Franco-Prussian War of 1870-1871. He
wrote down his first “thoughts about an airship” in his diary on
March 25, 1874, inspired by an article about flying and international
mail. Zeppelin soon lost interest in this idea of civilian uses for an
airship and concentrated instead on the idea that dirigible balloons
might become an important part of modern warfare. He asked the

268 / Dirigible
German government to fund his research, pointing out that France
had a better military air force than Germany did. Zeppelin’s patriotism
was what kept him trying, in spite of money problems and
technical difficulties.
In 1893, in order to get more money, Zeppelin tried to persuade
the German military and engineering experts that his invention was
practical. Even though a government committee decided that his
work was worth a small amount of funding, the army was not sure
that Zeppelin’s dirigible was worth the cost. Finally, the committee
chose Schwarz’s design. In 1896, however, Zeppelin won the support
of the powerful Union of German Engineers, which in May,
1898, gave him 800,000 marks to form a stock company called the
Association for the Promotion of Airship Flights. In 1899, Zeppelin
began building his dirigible in Manzell at Lake Constance. In July,
1900, the airship was finished and ready for its first test flight.
Several Attempts
Zeppelin, together with his engineer, Theodor Kober, had worked
on the design since May, 1892, shortly after Zeppelin’s retirement
from the army. They had finished the rough draft by 1894, and
though they made some changes later, this was the basic design of
the Zeppelin. An improved version was patented in December,
1897.
In the final prototype, called the LZ 1, the engineers tried to make
the airship as light as possible. They used a light internal combustion
engine and designed a frame made of the light metal aluminum.
The airship was 128 meters long and had a diameter of 11.7
meters when inflated. Twenty-four zinc-aluminum girders ran the
length of the ship, being drawn together at each end. Sixteen rings
held the body together. The engineers stretched an envelope of
smooth cotton over the framework to reduce wind resistance and to
protect the gas bags from the sun’s rays. Seventeen gas bags made of
rubberized cloth were placed inside the framework. Together they
held more than 120,000 cubic meters of hydrogen gas, which would
lift 11,090 kilograms. Two motor gondolas were attached to the
sides, each with a 16-horsepower gasoline engine, spinning four
propellers.

Count Ferdinand von Zeppelin
Dirigible / 269
The Zeppelin, the first lighter-than-air craft that was powered
and steerable, began as a retirement project.
Count Ferdinand von Zeppelin was born near Lake Constance
in southern Germany in 1838 and grew up in a family
long used to aristocratic privilege and government service. After
studying engineering at the University of Tübingen, he was
commissioned as a lieutenant of engineers. In 1863 he traveled
to the United States and, armed with a letter of introduction
from President Abraham Lincoln, toured the Union emplacements.
The observation balloons then used to see behind enemy
lines impressed him. He learned all he could about them and
even flew up in one to seven hundred feet.
His enthusiasm for airships stayed with him throughout his
career, but he was not really able to apply himself to the problem
until he retired (as a brigadier general) in 1890. Then he
concentrated on the struggle to line up financing and attract talented
help. He found investors for 90 percent of the money he
needed and got the rest from his wife’s inheritance. The first
LZ’s (Luftschiff Zeppelin) had troubles, but setbacks did not stop
him. He was a stubborn, determined man. By the time he died
in 1917 near Berlin he had seen ninety-two airships built. And
because his design was so thoroughly associated with lighterthan-air
vessels in the mind of the German public, they have
ever after been known as zeppelins. However, he had already
recognized their vulnerability as military aircraft, his main interest,
and so he had turned his attention to designs for large
airplanes as bombers.
The test flight did not go well. The two main questions—whether
the craft was strong enough and fast enough—could not be answered
because little things kept going wrong; for example, a crankshaft
broke and a rudder jammed. The first flight lasted no more
than eighteen minutes, with a maximum speed of 13.7 kilometers
per hour. During all three test flights, the airship was in the air for a
total of only two hours, going no faster than 28.2 kilometers per
hour.
Zeppelin had to drop the project for some years because he ran
out of money, and his company was dissolved. The LZ 1 was

270 / Dirigible
wrecked in the spring of 1901. A second airship was tested in November,
1905, and January, 1906. Both tests were unsuccessful, and
in the end the ship was destroyed during a storm.
By 1906, however, the German government was convinced of the
military usefulness of the airship, though it would not give money
to Zeppelin unless he agreed to design one that could stay in the air
for at least twenty-four hours. The third Zeppelin failed this test in
the autumn of 1907. Finally, in the summer of 1908, the LZ 4 not only
proved itself to the military but also attracted great publicity. It flew
for more than twenty-four hours and reached a speed of more than
60 kilometers per hour. Caught in a storm at the end of this flight,
the airship was forced to land and exploded, but money came from
all over Germany to build another.
Impact
Most rigid airships were designed and flown in Germany. Of the
161 that were built between 1900 and 1938, 139 were made in Germany,
and 119 were based on the Zeppelin design.
More than 80 percent of the airships were built for the military.
The Germans used more than one hundred for gathering information
and for bombing during World War I (1914-1918). Starting in
May, 1915, airships bombed Warsaw, Poland; Bucharest, Romania;
Salonika, Greece; and London, England. This was mostly a fear tactic,
since the attacks did not cause great damage, and the English antiaircraft
defense improved quickly. By 1916, the German army had
lost so many airships that it stopped using them, though the navy
continued.
Airships were first used for passenger flights in 1910. By 1914,
the Delag (German Aeronautic Stock Company) used seven passenger
airships for sightseeing trips around German cities. There were
still problems with engine power and weather forecasting, and it
was difficult to move the airships on the ground. After World War I,
the Zeppelins that were left were given to the Allies as payment,
and the Germans were not allowed to build airships for their own
use until 1925.
In the 1920’s and 1930’s, it became cheaper to use airplanes for

short flights, so airships were useful mostly for long-distance flight.
A British airship made the first transatlantic flight in 1919. The British
hoped to connect their empire by means of airships starting in
1924, but the 1930 crash of the R-101, in which most of the leading
English aeronauts were killed, brought that hope to an end.
The United States Navy built the Akron (1931) and the Macon
(1933) for long-range naval reconnaissance, but both airships crashed.
Only the Germans continued to use airships on a regular basis. In
1929, the world tour of the Graf Zeppelin was a success. Regular
flights between Germany and South America started in 1932, and in
1936, German airships bearing Nazi swastikas flew to Lakehurst,
New Jersey. The tragic explosion of the hydrogen-filled Hindenburg
in 1937, however, brought the era of the rigid airship to a close. The
U.S. secretary of the interior vetoed the sale of nonflammable helium,
fearing that the Nazis would use it for military purposes, and
the German government had to stop transatlantic flights for safety
reasons. In 1940, the last two remaining rigid airships were destroyed.
See also Airplane; Gyrocompass; Stealth aircraft; Supersonic
passenger plane; Turbojet.
Further Reading
Dirigible / 271
Brooks, Peter. Zeppelin: Rigid Airships, 1893-1940. London: Putman,
1992.
Chant, Christopher. The Zeppelin: The History of German Airships from
1900-1937. New York: Barnes and Noble Books, 2000.
Griehl, Manfred, and Joachim Dressel. Zeppelin! The German Airship
Story. New York: Sterling Publishing, 1990.
Syon, Guillaume de. Zeppelin!: Germany and the Airship, 1900-1939.
Baltimore: John Hopkins University Press, 2001.

272
Disposable razor
Disposable razor
The invention: An inexpensive shaving blade that replaced the traditional
straight-edged razor and transformed shaving razors
into a frequent household purchase item.
The people behind the invention:
King Camp Gillette (1855-1932), inventor of the disposable razor
Steven Porter, the machinist who created the first three
disposable razors for King Camp Gillette
William Emery Nickerson (1853-1930), an expert machine
inventor who created the machines necessary for mass
production
Jacob Heilborn, an industrial promoter who helped Gillette start
his company and became a partner
Edward J. Stewart, a friend and financial backer of Gillette
Henry Sachs, an investor in the Gillette Safety Razor Company
John Joyce, an investor in the Gillette Safety Razor Company
William Painter (1838-1906), an inventor who inspired Gillette
George Gillette, an inventor, King Camp Gillette’s father
A Neater Way to Shave
In 1895, King Camp Gillette thought of the idea of a disposable razor
blade. Gillette spent years drawing different models, and finally
Steven Porter, a machinist and Gillette’s associate, created from those
drawings the first three disposable razors that worked. Gillette soon
founded the Gillette Safety Razor Company, which became the leading
seller of disposable razor blades in the United States.
George Gillette, King Camp Gillette’s father, had been a newspaper
editor, a patent agent, and an inventor. He never invented a very
successful product, but he loved to experiment. He encouraged all
of his sons to figure out how things work and how to improve on
them. King was always inventing something new and had many
patents, but he was unsuccessful in turning them into profitable
businesses.
Gillette worked as a traveling salesperson for Crown Cork and

Seal Company. William Painter, one of Gillette’s friends and the inventor
of the crown cork, presented Gillette with a formula for making
a fortune: Invent something that would constantly need to be replaced.
Painter’s crown cork was used to cap beer and soda bottles.
It was a tin cap covered with cork, used to form a tight seal over a
bottle. Soda and beer companies could use a crown cork only once
and needed a steady supply.
King took Painter’s advice and began thinking of everyday items
that needed to be replaced often. After owning a Star safety razor
for some time, King realized that the razor blade had not been improved
for a long time. He studied all the razors on the market and
found that both the common straight razor and the safety razor featured
a heavy V-shaped piece of steel, sharpened on one side. King
reasoned that a thin piece of steel sharpened on both sides would
create a better shave and could be thrown away once it became dull.
The idea of the disposable razor had been born.
Gillette made several drawings of disposable razors. He then
made a wooden model of the razor to better explain his idea.
Gillette’s first attempt to construct a working model was unsuccessful,
as the steel was too flimsy. Steven Porter, a Boston machinist, decided
to try to make Gillette’s razor from his drawings. He produced
three razors, and in the summer of 1899 King was the first
man to shave with a disposable razor.
Changing Consumer Opinion
Disposable razor / 273
In the early 1900’s, most people considered a razor to be a oncein-a-lifetime
purchase. Many fathers handed down their razors to
their sons. Straight razors needed constant and careful attention to
keep them sharp. The thought of throwing a razor in the garbage after
several uses was contrary to the general public’s idea of a razor.
If Gillette’s razor had not provided a much less painful and faster
shave, it is unlikely that the disposable would have been a success.
Even with its advantages, public opinion against the product was
still difficult to overcome.
Financing a company to produce the razor proved to be a major
obstacle. King did not have the money himself, and potential investors
were skeptical. Skepticism arose both because of public percep-

274 / Disposable razor
tions of the product and because of its manufacturing process. Mass
production appeared to be impossible, but the disposable razor
would never be profitable if produced using the methods used to
manufacture its predecessor.
William Emery Nickerson, an expert machine inventor, had looked
at Gillette’s razor and said it was impossible to create a machine to
produce it. He was convinced to reexamine the idea and finally created
a machine that would create a workable blade. In the process,
Nickerson changed Gillette’s original model. He improved the handle
and frame so that it would better support the thin steel blade.
In the meantime, Gillette was busy getting his patent assigned to
the newly formed American Safety Razor Company, owned by
Gillette, Jacob Heilborn, Edward J. Stewart, and Nickerson. Gillette
owned considerably more shares than anyone else. Henry Sachs
provided additional capital, buying shares from Gillette.
The stockholders decided to rename the company the Gillette
Safety Razor Company. It soon spent most of its money on machinery
and lacked the capital it needed to produce and advertise its
product. The only offer the company had received was from a group
of New York investors who were willing to give $125,000 in exchange
for 51 percent of the company. None of the directors wanted
to lose control of the company, so they rejected the offer.
John Joyce, a friend of Gillette, rescued the financially insecure
new company. He agreed to buy $100,000 worth of bonds from the
company for sixty cents on the dollar, purchasing the bonds gradually
as the company needed money. He also received an equivalent
amount of company stock. After an investment of $30,000, Joyce
had the option of backing out. This deal enabled the company to
start manufacturing and advertising.
Impact
The company used $18,000 to perfect the machinery to produce
the disposable razor blades and razors. Originally the directors
wanted to sell each razor with twenty blades for three dollars. Joyce
insisted on a price of five dollars. In 1903, five dollars was about
one-third of the average American’s weekly salary, and a highquality
straight razor could be purchased for about half that price.

Disposable razor / 275
The other directors were skeptical, but Joyce threatened to buy up
all the razors for three dollars and sell them himself for five dollars.
Joyce had the financial backing to make this promise good, so the directors
agreed to the higher price.
The Gillette Safety Razor Company contracted with Townsend &
Hunt for exclusive sales. The contract stated that Townsend & Hunt
would buy 50,000 razors with twenty blades each during a period of
slightly more than a year and would purchase 100,000 sets per year
for the following four years. The first advertisement for the product
appeared in System Magazine in early fall of 1903, offering the razors
by mail order. By the end of 1903, only fifty-one razors had been
sold.
Since Gillette and most of the directors of the company were not
salaried, Gillette had needed to keep his job as salesman with
Crown Cork and Seal. At the end of 1903, he received a promotion
that meant relocation from Boston to London. Gillette did not want
to go and pleaded with the other directors, but they insisted that the
company could not afford to put him on salary. The company decided
to reduce the number of blades in a set from twenty to twelve
in an effort to increase profits without noticeably raising the cost of a
set. Gillette resigned the title of company president and left for England.
Shortly thereafter, Townsend & Hunt changed its name to the
Gillette Sales Company, and three years later the sales company
sold out to the parent company for $300,000. Sales of the new type
of razor were increasing rapidly in the United States, and Joyce
wanted to sell patent rights to European companies for a small percentage
of sales. Gillette thought that that would be a horrible mistake
and quickly traveled back to Boston. He had two goals: to stop
the sale of patent rights, based on his conviction that the foreign
market would eventually be very lucrative, and to become salaried
by the company. Gillette accomplished both these goals and soon
moved back to Boston.
Despite the fact that Joyce and Gillette had been good friends for
a long time, their business views often differed. Gillette set up a
holding company in an effort to gain back controlling interest in the
Gillette Safety Razor Company. He borrowed money and convinced
his allies in the company to invest in the holding company, eventu-

276 / Disposable razor
ally regaining control. He was reinstated as president of the company.
One clear disagreement was that Gillette wanted to relocate the company
to Newark, New Jersey, and Joyce thought that that would be a
waste of money. Gillette authorized company funds to be invested in
a Newark site. The idea was later dropped, costing the company a
large amount of capital. Gillette was not a very wise businessman
King Camp Gillette
At age sixteen, King Camp Gillette (1855-1932) saw all of his
family’s belongings consumed in the Great Chicago Fire. He
had to drop out of school because of it and earn his own living.
The catastrophe and the sudden loss of security that followed
shaped his ambitions. He was not about to risk destitution ever
again.
He made himself a successful traveling salesman but still
felt he was earning too little. So he turned his mind to inventions,
hoping to get rich quick. The disposable razor was his
only venture, but it was enough. After its long preparation for
marketing Gillette’s invention and some subsequent turmoil
among its board of directors, the Gillette Safety Razor Company
was a phenomenal success and a bonanza for Gillette. He
became wealthy. He retired in 1913, just ten years after the company
opened, his security assured.
His mother had written cookbooks, one of which was a bestseller.
As an adult, Gillette got the writing bug himself and
wrote four books, but his theme was far loftier than cooking—
social theory and security for the masses. Like Karl Marx he argued
that economic competition squanders human resources
and leads to deprivation, which in turn leads to crime. So, he
reasoned, getting rid of economic competition will end misery
and crime. He recommended that a centralized agency plan
production and oversee distribution, a recommendation that
America resoundingly ignored. However, other ideas of his
eventually found acceptance, such as air conditioning for workers
and government assistance for the unemployed.
In 1922 Gillette moved to Los Angeles, California, and devoted
himself to raising oranges and collecting his share of the
company profits. However, he seldom felt free enough with his
money to donate it to charity or finance social reform.

Disposable razor / 277
and made many costly mistakes. Joyce even accused him of deliberately
trying to keep the stock price low so that Gillette could purchase
more stock. Joyce eventually bought out Gillette, who retained
his title as president but had little say about company
business.
With Gillette out of a management position, the company became
more stable and more profitable. The biggest problem the
company faced was that it would soon lose its patent rights. After
the patent expired, the company would have competition. The company
decided that it could either cut prices (and therefore profits) to
compete with the lower-priced disposables that would inevitably
enter the market, or it could create a new line of even better razors.
The company opted for the latter strategy. Weeks before the patent
expired, the Gillette Safety Razor Company introduced a new line
of razors.
Both World War I and World War II were big boosts to the company,
which contracted with the government to supply razors to almost
all the troops. This transaction created a huge increase in sales
and introduced thousands of young men to the Gillette razor. Many
of them continued to use Gillettes after returning from the war.
Aside from the shaky start of the company, its worst financial difficulties
were during the Great Depression. Most Americans simply
could not afford Gillette blades, and many used a blade for an extended
time and then resharpened it rather than throwing it away. If
it had not been for the company’s foreign markets, the company
would not have shown a profit during the Great Depression.
Gillette’s obstinancy about not selling patent rights to foreign investors
proved to be an excellent decision.
The company advertised through sponsoring sporting events,
including the World Series. Gillette had many celebrity endorsements
from well-known baseball players. Before it became too expensive
for one company to sponsor an entire event, Gillette had
exclusive advertising during the World Series, various boxing
matches, the Kentucky Derby, and football bowl games. Sponsoring
these events was costly, but sports spectators were the typical
Gillette customers.
The Gillette Company created many products that complemented
razors and blades, including shaving cream, women’s ra-

278 / Disposable razor
zors, and electric razors. The company expanded into new products
including women’s cosmetics, writing utensils, deodorant, and
wigs. One of the main reasons for obtaining a more diverse product
line was that a one-product company is less stable, especially in a
volatile market. The Gillette Company had learned that lesson in
the Great Depression. Gillette continued to thrive by following the
principles the company had used from the start. The majority of
Gillette’s profits came from foreign markets, and its employees
looked to improve products and find opportunities in other departments
as well as their own.
See also Contact lenses; Memory metal; Steelmaking process.
Further Reading
Adams, Russell B., Jr. King C. Gillette: The Man and His Wonderful
Shaving Device. Boston: Little, Brown, 1978.
Dowling, Tim. Inventor of the Disposable Culture: King Camp Gillette,
1855-1932. London: Short, 2001.
“Gillette: Blade-runner.” The Economist 327 (April 10, 1993).
Killgren, Lucy. “Nicking Gillette.” Marketing Week 22 (June 17, 1999).
McKibben, Gordon. Cutting Edge: Gillette’s Journey to Global Leadership.
Boston, Mass.: Harvard Business School Press, 1998.
Thomas, Robert J. New Product Success Stories: Lessons from Leading
Innovators. New York: John Wiley, 1995.
Zeien, Alfred M. The Gillette Company. New York: Newcomen Society
of the United States, 1999.

Dolby noise reduction
Dolby noise reduction
The invention: Electronic device that reduces the signal-to-noise
ratio of sound recordings and greatly improves the sound quality
of recorded music.
The people behind the invention:
Emil Berliner (1851-1929), a German inventor
Ray Milton Dolby (1933- ), an American inventor
Thomas Alva Edison (1847-1931), an American inventor
Phonographs, Tapes, and Noise Reduction
279
The main use of record, tape, and compact disc players is to listen
to music, although they are also used to listen to recorded speeches,
messages, and various forms of instruction. Thomas Alva Edison
invented the first sound-reproducing machine, which he called the
“phonograph,” and patented it in 1877. Ten years later, a practical
phonograph (the “gramophone”) was marketed by a German, Emil
Berliner. Phonographs recorded sound by using diaphragms that
vibrated in response to sound waves and controlled needles that cut
grooves representing those vibrations into the first phonograph records,
which in Edison’s machine were metal cylinders and in Berliner’s
were flat discs. The recordings were then played by reversing
the recording process: Placing a needle in the groove in the recorded
cylinder or disk caused the diaphragm to vibrate, re-creating the
original sound that had been recorded.
In the 1920’s, electrical recording methods developed that produced
higher-quality recordings, and then, in the 1930’s, stereophonic
recording was developed by various companies, including
the British company Electrical and Musical Industries (EMI). Almost
simultaneously, the technology of tape recording was developed.
By the 1940’s, long-playing stereo records and tapes were
widely available. As recording techniques improved further, tapes
became very popular, and by the 1960’s, they had evolved into both
studio master recording tapes and the audio cassettes used by consumers.

280 / Dolby noise reduction
Hisses and other noises associated with sound recording and its
environment greatly diminished the quality of recorded music. In
1967, Ray Dolby invented a noise reducer, later named “Dolby A,”
that could be used by recording studios to reduce tape signal-tonoise
ratios. Several years later, his “Dolby B” system, designed
for home use, became standard equipment in all types of playback
machines. Later, Dolby and others designed improved noisesuppression
systems.
Recording and Tape Noise
Sound is made up of vibrations of varying frequencies—sound
waves—that sound recorders can convert into grooves on plastic records,
varying magnetic arrangements on plastic tapes covered
with iron particles, or tiny pits on compact discs. The following discussion
will focus on tape recordings, for which the original Dolby
noise reducers were designed.
Tape recordings are made by a process that converts sound
waves into electrical impulses that cause the iron particles in a tape
to reorganize themselves into particular magnetic arrangements.
The process is reversed when the tape is played back. In this process,
the particle arrangements are translated first into electrical impulses
and then into sound that is produced by loudspeakers.
Erasing a tape causes the iron particles to move back into their original
spatial arrangement.
Whenever a recording is made, undesired sounds such as hisses,
hums, pops, and clicks can mask the nuances of recorded sound, annoying
and fatiguing listeners. The first attempts to do away with
undesired sounds (noise) involved making tapes, recording devices,
and recording studios quieter. Such efforts did not, however,
remove all undesired sounds.
Furthermore, advances in recording technology increased the
problem of noise by producing better instruments that “heard” and
transmitted to recordings increased levels of noise. Such noise is often
caused by the components of the recording system; tape hiss is
an example of such noise. This type of noise is most discernible in
quiet passages of recordings, because loud recorded sounds often
mask it.

Ray Dolby
Dolby noise reduction / 281
Ray Dolby, born in Portland, Oregon, in 1933, became an
electronics engineer while still in high school in 1952. That is
when he began working part time for Ampex Corporation,
helping develop the first videotape recorder. He was responsible
for the electronics in the Ampex VTR, which was marketed
in 1956. The next year he finished a bachelor of science degree at
Stanford University, won a Marshall Scholarship and National
Science Foundation grant, and went to Cambridge University
in England for graduate studies. He received a Ph.D. in 1961
and a fellowship to Pembroke College, during which he also
consulted for the United Kingdom Atomic Energy Authority.
After two years in India as a United Nations adviser, he set
up Dolby Laboratories in London. It was there that he produced
the sound suppression equipment that made him famous to audiophiles
and movie goers, particularly in the 1970’s for the
Dolby stereo (“surround sound”) that enlivened such blockbusters
as Star Wars. In 1976 he moved to San Francisco and
opened new offices for his company. The holder of more than
fifty patents, Dolby published monographs on videotape recording,
long wavelength X-ray analysis, and noise reduction.
He is among the most honored scientists in the recording industry.
Among many other awards, he received an Oscar, Emmy,
Samuel L. Warner Memorial Award, gold and silver medals
from the Audio Engineering Society, and the National Medal of
Technology. England made him an honorary Officer of the Most
Excellent Order of the British Empire, and Cambridge University
and York University awarded him honorary doctorates.
Because of the problem of noise in quiet passages of recorded
sound, one early attempt at noise suppression involved the reduction
of noise levels by using “dynaural” noise suppressors. These
devices did not alter the loud portions of a recording; instead, they
reduced the very high and very low frequencies in the quiet passages
in which noise became most audible. The problem with such
devices was, however, that removing the high and low frequencies
could also affect the desirable portions of the recorded sound.
These suppressors could not distinguish desirable from undesirable
sounds. As recording techniques improved, dynaural noise sup-

282 / Dolby noise reduction
pressors caused more and more problems, and their use was finally
discontinued.
Another approach to noise suppression is sound compression
during the recording process. This compression is based on the fact
that most noise remains at a constant level throughout a recording,
regardless of the sound level of a desired signal (such as music). To
carry out sound compression, the lowest-level signals in a recording
are electronically elevated above the sound level of all noise. Musical
nuances can be lost when the process is carried too far, because
the maximum sound level is not increased by devices that use
sound compression. To return the music or other recorded sound to
its normal sound range for listening, devices that “expand” the recorded
music on playback are used. Two potential problems associated
with the use of sound compression and expansion are the difficulty
of matching the two processes and the introduction into the
recording of noise created by the compression devices themselves.
In 1967, Ray Dolby developed Dolby A to solve these problems as
they related to tape noise (but not to microphone signals) in the recording
and playing back of studio master tapes. The system operated
by carrying out ten-decibel compression during recording and
then restoring (noiselessly) the range of the music on playback. This
was accomplished by expanding the sound exactly to its original
range. Dolby A was very expensive and was thus limited to use in recording
studios. In the early 1970’s, however, Dolby invented the less
expensive Dolby B system, which was intended for consumers.
Consequences
The development of Dolby A and Dolby B noise-reduction systems
is one of the most important contributions to the high-quality
recording and reproduction of sound. For this reason, Dolby A
quickly became standard in the recording industry. In similar fashion,
Dolby B was soon incorporated into virtually every highfidelity
stereo cassette deck to be manufactured.
Dolby’s discoveries spurred advances in the field of noise reduction.
For example, the German company Telefunken and the Japanese
companies Sanyo and Toshiba, among others, developed their
own noise-reduction systems. Dolby Laboratories countered by

producing an improved system: Dolby C. The competition in the
area of noise reduction continues, and it will continue as long as
changes in recording technology produce new, more sensitive recording
equipment.
See also Cassette recording; Compact disc; Electronic synthesizer;
FM radio; Radio; Transistor; Transistor radio; Walkman cassette
player.
Further Reading
Dolby noise reduction / 283
Alkin, E. G. M. Sound Recording and Reproduction. 3d ed. Boston: Focal
Press, 1996.
Baldwin, Neil. Edison: Inventing the Century. Chicago: University of
Chicago Press, 2001.
Wile, Frederic William. Emile Berliner, Maker of the Microphone. New
York: Arno Press, 1974.

284
Electric clock
Electric clock
The invention: Electrically powered time-keeping device with a
quartz resonator that has led to the development of extremely accurate,
relatively inexpensive electric clocks that are used in computers
and microprocessors.
The person behind the invention:
Warren Alvin Marrison (1896-1980), an American scientist
From Complex Mechanisms to Quartz Crystals
William Alvin Marrison’s fabrication of the electric clock began a
new era in time-keeping. Electric clocks are more accurate and more
reliable than mechanical clocks, since they have fewer moving parts
and are less likely to malfunction.
An electric clock is a device that generates a string of electric
pulses. The most frequently used electric clocks are called “free running”
and “periodic,” which means that they generate a continuous
sequence of electric pulses that are equally spaced. There are various
kinds of electronic “oscillators” (materials that vibrate) that can
be used to manufacture electric clocks.
The material most commonly used as an oscillator in electric
clocks is crystalline quartz. Because quartz (silicon dioxide) is a
completely oxidized compound (which means that it does not deteriorate
readily) and is virtually insoluble in water, it is chemically
stable and resists chemical processes that would break down other
materials. Quartz is a “piezoelectric” material, which means that it
is capable of generating electricity when it is subjected to pressure
or stress of some kind. In addition, quartz has the advantage of generating
electricity at a very stable frequency, with little variation. For
these reasons, quartz is an ideal material to use as an oscillator.
The Quartz Clock
A quartz clock is an electric clock that makes use of the piezoelectric
properties of a quartz crystal. When a quartz crystal vibrates, a

Early electric clock. (PhotoDisc)
Electric clock / 285
difference of electric potential is produced between two of its faces.
The crystal has a natural frequency (rate) of vibration that is determined
by its size and shape. If the crystal is placed in an oscillating
electric circuit that has a frequency that is nearly the same as that of
the crystal, it will vibrate at its natural frequency and will cause the
frequency of the entire circuit to match its own frequency.
Piezoelectricity is electricity, or “electric polarity,” that is caused
by the application of mechanical pressure on a “dielectric” material
(one that does not conduct electricity), such as a quartz crystal. The
process also works in reverse; if an electric charge is applied to the
dielectric material, the material will experience a mechanical distortion.
This reciprocal relationship is called “the piezoelectric effect.”
The phenomenon of electricity being generated by the application
of mechanical pressure is called the direct piezoelectric effect, and
the phenomenon of mechanical stress being produced as a result of
the application of electricity is called the converse piezoelectric
effect.
When a quartz crystal is used to create an oscillator, the natural
frequency of the crystal can be used to produce other frequencies
that can power clocks. The natural frequency of a quartz crystal is
nearly constant if precautions are taken when it is cut and polished
and if it is maintained at a nearly constant temperature and pressure.
After a quartz crystal has been used for some time, its fre-

286 / Electric clock
Warren Alvin Marrison
Born in Invenary, Canada, in 1896, Warren Alvin Marrison
completed high school at Kingston Collegiate Institute in Ontario
and attended Queen’s University in Kingston, where he
studied science. World War I interrupted his studies, and while
serving in the Royal Flying Corps as an electronics researcher,
he began his life-long interest in radio. He graduated from university
with a degree in engineering physics in 1920, transferred
to Harvard University in 1921, and earned a master’s degree.
After his studies, he worked for the Western Electric Company
in New York, helping to develop a method to record
sound on film. He moved to the company’s Bell Laboratory in
1925 and studied how to produce frequency standards for radio
transmissions. This research led him to use quartz crystals as
oscillators, and he was able to step down the frequency enough
that it could power a motor. Because the motor revolved at the
same rate as the crystal’s frequency, he could determine the
number of vibrations per time unit of the crystal and set a frequency
standard. However, because the vibrations were constant
over time, the crystal also measured time, and a new type
of clock was born.
For his work, Marrison received the British Horological Institute’s
Gold Medal in 1947 and the Clockmakers’ Company’s
Tompion Medal in 1955. He died in California in 1980.
quency usually varies slowly as a result of physical changes. If allowances
are made for such changes, quartz-crystal clocks such as
those used in laboratories can be manufactured that will accumulate
errors of only a few thousandths of a second per month. The
quartz crystals that are typically used in watches, however, may accumulate
errors of tens of seconds per year.
There are other materials that can be used to manufacture accurate
electric clocks. For example, clocks that use the element rubidium
typically would accumulate errors no larger than a few tenthousandths
of a second per year, and those that use the element cesium
would experience errors of only a few millionths of a second
per year. Quartz is much less expensive than rarer materials such as

ubidium and cesium, and it is easy to use in such common applications
as computers. Thus, despite their relative inaccuracy, electric
quartz clocks are extremely useful and popular, particularly for applications
that require accurate timekeeping over a relatively short
period of time. In such applications, quartz clocks may be adjusted
periodically to correct for accumulated errors.
Impact
The electric quartz clock has contributed significantly to the development
of computers and microprocessors. The computer’s control
unit controls and synchronizes all data transfers and transformations
in the computer system and is the key subsystem in the
computer itself. Every action that the computer performs is implemented
by the control unit.
The computer’s control unit uses inputs from a quartz clock to
derive timing and control signals that regulate the actions in the system
that are associated with each computer instruction. The control
unit also accepts, as input, control signals generated by other devices
in the computer system.
The other primary impact of the quartz clock is in making the
construction of multiphase clocks a simple task. A multiphase
clock is a clock that has several outputs that oscillate at the same
frequency. These outputs may generate electric waveforms of different
shapes or of the same shape, which makes them useful for
various applications. It is common for a computer to incorporate a
single-phase quartz clock that is used to generate a two-phase
clock.
See also Atomic clock; Carbon dating; Electric refrigerator; Fluorescent
lighting; Microwave cooking; Television; Vacuum cleaner;
Washing machine.
Further Reading
Electric clock / 287
Barnett, Jo Ellen. Time’s Pendulum: From Sundials to Atomic Clocks, the
Fascinating History of Time Keeping and How Our Discoveries
Changed the World. San Diego: Harcourt Brace, 1999.

288 / Electric clock
Dennis, Maggie, and Carlene Stephens. “Engineering Time: Inventing
the Electronic Wristwatch.” British Journal for the History
of Science 33, no. 119 (December, 2000).
Ganeri, Anita. From Candle to Quartz Clock: The Story of Time and
Timekeeping. London: Evna Brothers, 1996.
Thurber, Karl. “All the Time in the World.” Popular Electronics 14, no.
10 (October, 1997).

Electric refrigerator
Electric refrigerator
The invention: An electrically powered and hermetically sealed
food-storage appliance that replaced iceboxes, improved production,
and lowered food-storage costs.
The people behind the invention:
Marcel Audiffren, a French monk
Christian Steenstrup (1873-1955), an American engineer
Fred Wolf, an American engineer
Ice Preserves America’s Food
289
Before the development of refrigeration in the United States, a
relatively warm climate made it difficult to preserve food. Meat
spoiled within a day and milk could spoil within an hour after milking.
In early America, ice was stored below ground in icehouses that
had roofs at ground level. George Washington had a large icehouse
at his Mount Vernon estate. By 1876, America was consuming more
than 2 million tons of ice each year, which required 4,000 horses and
10,000 men to deliver.
Several related inventions were needed before mechanical refrigeration
was developed. James Watt invented the condenser, an important
refrigeration system component, in 1769. In 1805, Oliver Evans
presented the idea of continuous circulation of a refrigerant in a
closed cycle. In this closed cooling cycle, a liquid refrigerant evaporates
to a gas at low temperature, absorbing heat from its environment
and thereby producing “cold,” which is circulated around an
enclosed cabinet. To maintain this cooling cycle, the refrigerant gas
must be returned to liquid form through condensation by compression.
The first closed-cycle vapor-compression refrigerator, which
was patented by Jacob Perkins in 1834, used ether as a refrigerant.
Iceboxes were used in homes before refrigerators were developed.
Ice was cut from lakes and rivers in the northern United States
or produced by ice machines in the southern United States. An ice
machine using air was patented by John Gorrie at New Orleans in
1851. Ferdinand Carre introduced the first successful commercial

290 / Electric refrigerator
ice machine, which used ammonia as a refrigerant, in 1862, but it
was too large for home use and produced only a pound of ice per
hour. Ice machinery became very dependable after 1890 but was
plagued by low efficiency. Very warm summers in 1890 and 1891 cut
natural ice production dramatically and increased demand for mechanical
ice production. Ice consumption continued to increase after
1890; by 1914, 21 million tons of ice were used annually. The high
prices charged for ice and the extremely low efficiency of home iceboxes
gradually led the public to demand a substitute for ice refrigeration.
Refrigeration for the Home
Domestic refrigeration required a compact unit with a built-in
electric motor that did not require supervision or maintenance.
Marcel Audiffren, a French monk, conceived the idea of an electric
refrigerator for home use around 1910. The first electric refrigerator,
which was invented by Fred Wolf in 1913, was called the Domelre,
which stood for domestic electric refrigerator. This machine used
condensation equipment that was housed in the home’s basement.
In 1915, Alfred Mellowes built the first refrigerator to contain all of
its components; this machine was known as Guardian’s Frigerator.
General Motors acquired Guardian in 1918 and began to mass produce
refrigerators. Guardian was renamed Frigidaire in 1919. In
1918, the Kelvinator Company, run by Edmund Copeland, built the
first refrigerator with automatic controls, the most important of
which was the thermostatic switch. Despite these advances, by 1920
only a few thousand homes had refrigerators, which cost about
$1,000 each.
The General Electric Company (GE) purchased the rights to the
General Motors refrigerator, which was based on an improved
design submitted by one of its engineers, Christian Steenstrup.
Steenstrup’s innovative design included a motor and reciprocating
compressor that were hermetically sealed with the refrigerant.
This unit, known as the GE Monitor Top, was first produced in
1927. A patent on this machine was filed for in 1926 and granted to
Steenstrup in 1930. Steenstrup became chief engineer of GE’s electric
refrigeration department and accumulated thirty-nine addi-

Electric refrigerator / 291
tional patents in refrigeration over the following years. By 1936, he
had more than one hundred patents to his credit in refrigeration and
other areas.
Further refinement of the refrigerator evolved with the development
of Freon, a nonexplosive, nontoxic, and noncorrosive refrigerant
discovered by Thomas Midgely, Jr., in 1928. Freon used lower
pressures than ammonia did, which meant that lighter materials
and lower temperatures could be used in refrigeration.
During the years following the introduction of the Monitor Top,
the cost of refrigerators dropped from $1,000 in 1918 to $400 in 1926,
and then to $170 in 1935. Sales of units increased from 200,000 in
1926 to 1.5 million in 1935.
Initially, refrigerators were sold separately from their cabinets,
which commonly were used wooden iceboxes. Frigidaire began
making its own cabinets in 1923, and by 1930, refrigerators that
combined machinery and cabinet were sold.
Throughout the 1930’s, refrigerators were well-insulated, hermetically
sealed steel units that used evaporator coils to cool the
food compartment. The refrigeration system was transferred from
on top of to below the food storage area, which made it possible to
raise the food storage area to a more convenient level. Special light
bulbs that produced radiation to kill taste- and odor-bearing bacteria
were used in refrigerators. Other developments included sliding
shelves, shelves in doors, rounded and styled cabinet corners, ice
cube trays, and even a built-in radio.
The freezing capacity of early refrigerators was inadequate. Only
a package or two of food could be kept cool at a time, ice cubes
melted, and only a minimal amount of food could be kept frozen.
The two-temperature refrigerator consisting of one compartment
providing normal cooling and a separate compartment for freezing
was developed by GE in 1939. Evaporator coils for cooling were
placed within the refrigerator walls, providing more cooling capacity
and more space for food storage. Frigidaire introduced a Cold
Wall compartment, while White-Westinghouse introduced a Colder
Cold system. After World War II, GE introduced the refrigeratorfreezer
combination.

292 / Electric refrigerator
Impact
Audiffren, Wolf, Steenstrup, and others combined the earlier inventions
of Watt, Perkins, and Carre with the development of electric
motors to produce the electric refrigerator. The development of
domestic electric refrigeration had a tremendous effect on the quality
of home life. Reliable, affordable refrigeration allowed consumers
a wider selection of food and increased flexibility in their daily
consumption. The domestic refrigerator with increased freezer capacity
spawned the growth of the frozen food industry. Without the
electric refrigerator, households would still depend on unreliable
supplies of ice.
See also Fluorescent lighting; Food freezing; Freeze-drying; Microwave
cooking; Refrigerant gas; Robot (household); Tupperware;
Vacuum cleaner; Washing machine.
Further Reading
Anderson, Oscar Edward. Refrigeration in America: A History of a New
Technology and Its Impact. Princeton: Princeton University Press,
1953.
Donaldson, Barry, Bernard Nagengast, and Gershon Meckler. Heat
and Cold: Mastering the Great Indoors: A Selective History of Heating,
Ventilation, Air-Conditioning and Refrigeration from the Ancients to
the 1930’s. Atlanta, Ga.: American Society of Heating, Refrigerating
and Air-Conditioning Engineers, 1994.
Woolrich, Willis Raymond. The Men Who Created Cold: A History of
Refrigeration. New York: Exposition Press, 1967.

Electrocardiogram
Electrocardiogram
The invention: Device for analyzing the electrical currents of the
human heart.
The people behind the invention:
Willem Einthoven (1860-1927), a Dutch physiologist and
winner of the 1924 Nobel Prize in Physiology or Medicine
Augustus D. Waller (1856-1922), a German physician and
researcher
Sir Thomas Lewis (1881-1945), an English physiologist
Horse Vibrations
293
In the late 1800’s, there was substantial research interest in the
electrical activity that took place in the human body. Researchers
studied many organs and systems in the body, including the nerves,
eyes, lungs, muscles, and heart. Because of a lack of available technology,
this research was tedious and frequently inaccurate. Therefore,
the development of the appropriate instrumentation was as
important as the research itself.
The initial work on the electrical activity of the heart (detected
from the surface of the body) was conducted by Augustus D. Waller
and published in 1887. Many credit him with the development of
the first electrocardiogram. Waller used a Lippmann’s capillary
electrometer (named for its inventor, the French physicist Gabriel-
Jonas Lippmann) to determine the electrical charges in the heart and
called his recording a “cardiograph.” The recording was made by
placing a series of small tubes on the surface of the body. The tubes
contained mercury and sulfuric acid. As an electrical current passed
through the tubes, the mercury would expand and contract. The resulting
images were projected onto photographic paper to produce
the first cardiograph. Yet Waller had only limited sucess with the
device and eventually abandoned it.
In the early 1890’s, Willem Einthoven, who became a good friend
of Waller, began using the same type of capillary tube to study the
electrical currents of the heart. Einthoven also had a difficult time

294 / Electrocardiogram
working with the instrument. His laboratory was located in an old
wooden building near a cobblestone street. Teams of horses pulling
heavy wagons would pass by and cause his laboratory to vibrate.
This vibration affected the capillary tube, causing the cardiograph
to be unclear. In his frustration, Einthoven began to modify his laboratory.
He removed the floorboards and dug a hole some ten to fifteen
feet deep. He lined the walls with large rocks to stabilize his instrument.
When this failed to solve the problem, Einthoven, too,
abandoned the Lippmann’s capillary tube. Yet Einthoven did not
abandon the idea, and he began to experiment with other instruments.
Electrocardiographs over the Phone
In order to continue his research on the electrical currents of the
heart, Einthoven began to work with a new device, the d’Arsonval
galvanometer (named for its inventor, the French biophysicist
Arsène d’Arsonval). This instrument had a heavy coil of wire suspended
between the poles of a horseshoe magnet. Changes in electrical
activity would cause the coil to move; however, Einthoven
found that the coil was too heavy to record the small electrical
changes found in the heart. Therefore, he modified the instrument
by replacing the coil with a silver-coated quartz thread (string).
The movements could be recorded by transmitting the deflections
through a microscope and projecting them on photographic film.
Einthoven called the new instrument the “string galvanometer.”
In developing his string galvanomter, Einthoven was influenced
by the work of one of his teachers, Johannes Bosscha. In the 1850’s,
Bosscha had published a study describing the technical complexities
of measuring very small amounts of electricity. He proposed the
idea that a galvanometer modified with a needle hanging from a
silk thread would be more sensitive in measuring the tiny electric
currents of the heart.
By 1905, Einthoven had improved the string galvanometer to
the point that he could begin using it for clinical studies. In 1906,
he had his laboratory connected to the hospital in Leiden by a telephone
wire. With this arrangement, Einthoven was able to study in
his laboratory electrocardiograms derived from patients in the

Willem Einthoven
Electrocardiogram / 295
Willem Einthoven was born in 1860 on the Island of Java,
now part of Indonesia. His father was a Dutch army medical officer,
and his mother was the daughter of the Finance Director
for the Dutch East Indies. When his father died in 1870, his
mother moved with her six children to Utrecht, Holland.
Einthoven entered the University of Utrecht in 1878 intending
to become a physician like his father, but physics and physiology
attracted him more. During his education two research
projects that he conducted brought him notoriety. The first involved
the articulation of the elbow, which he undertook after a
sports injury of his own elbow. (He remained an avid participant
in sports his whole life.) The second, which earned him his
doctorate in 1885, examined stereoscopy and color variation.
Because of the keen investigative abilities these studies displayed,
he was at once appointed professor of physiology at the
University of Leiden. He took up the position the next year, after
qualifying as a general practitioner.
Einthoven conducted research into asthma and the optics
and electrical activity of vision before turning his attention to
the heart. He developed the electrocardiogram in order to measure
the heart’s electrical activity accurately and tested its applications
and capacities with many students and visiting scientists,
helping thereby to widen interest in it as a diagnostic tool.
For this work he received the 1924 Nobel Prize in Physiology or
Medicine.
In his later years, Einthoven studied problems in acoustics
and the electrical activity of the sympathetic nervous system.
He died in Leiden in 1927.
hospital, which was located a mile away. With this source of subjects,
Einthoven was able to use his galvanometer to study many
heart problems. As a result of these studies, Einthoven identified
the following heart problems: blocks in the electrical conduction
system of the heart; premature beats of the heart, including two
premature beats in a row; and enlargements of the various chambers
of the heart. He was also able to study how the heart behaved
during the administration of cardiac drugs.

296 / Electrocardiogram
A major researcher who communicated with Einthoven about
the electrocardiogram was Sir Thomas Lewis, who is credited with
developing the electrocardiogram into a useful clinical tool. One of
Lewis’s important accomplishments was his identification of atrial
fibrillation, the overactive state of the upper chambers of the heart.
During World War I, Lewis was involved with studying soldiers’
hearts. He designed a series of graded exercises, which he used to
test the soldiers’ ability to perform work. From this study, Lewis
was able to use similar tests to diagnose heart disease and to screen
recruits who had heart problems.
Impact
As Einthoven published additional studies on the string galvanometer
in 1903, 1906, and 1908, greater interest in his instrument
was generated around the world. In 1910, the instrument, now
called the “electrocardiograph,” was installed in the United States.
It was the foundation of a new laboratory for the study of heart disease
at Johns Hopkins University.
As time passed, the use of the electrocardiogram—or “EKG,” as
it is familiarly known—increased substantially. The major advantage
of the EKG is that it can be used to diagnose problems in the
heart without incisions or the use of needles. It is relatively painless
for the patient; in comparison with other diagnostic techniques,
moreover, it is relatively inexpensive.
Recent developments in the use of the EKG have been in the area
of stress testing. Since many heart problems are more evident during
exercise, when the heart is working harder, EKGs are often
given to patients as they exercise, generally on a treadmill. The clinician
gradually increases the intensity of work the patient is doing
while monitoring the patient’s heart. The use of stress testing has
helped to make the EKG an even more valuable diagnostic tool.
See also Amniocentesis; Artificial heart; Blood transfusion; CAT
scanner; Coronary artery bypass surgery; Electroencephalogram;
Heart-lung machine; Mammography; Nuclear magnetic resonance;
Pacemaker; Ultrasound; X-ray image intensifier.

Further Reading
Electrocardiogram / 297
Cline, Barbara Lovett. Men Who Made a New Physics: Physicists and
the Quantum Theory. Chicago: University of Chicago Press, 1987.
Hollman, Arthur. Sir Thomas Lewis: Pioneer Cardiologist and Clinical
Scientist. New York: Springer, 1997.
Lewis, Thomas. Collected Works on Heart Disease. 1912. Reprint. New
York: Classics of Cardiology Library, 1991.
Snellen, H. A. Two Pioneers of Electrocardiography: The Correspondence
Between Einthoven and Lewis from 1908-1926. Rotterdam: Donker
Academic Publications, 1983.
_____. Willem Einthoven, 1860-1927, Father of Electrocardiography: Life
and Work, Ancestors and Contemporaries. Boston: Kluwer Academic
Publishers, 1995.

298
Electroencephalogram
Electroencephalogram
The invention: A system of electrodes that measures brain wave
patterns in humans, making possible a new era of neurophysiology.
The people behind the invention:
Hans Berger (1873-1941), a German psychiatrist and research
scientist
Richard Caton (1842-1926), an English physiologist and surgeon
The Electrical Activity of the Brain
Hans Berger’s search for the human electroencephalograph (English
physiologist Richard Caton had described the electroencephalogram,
or “brain wave,” in rabbits and monkeys in 1875) was motivated
by his desire to find a physiological method that might be
applied successfully to the study of the long-standing problem of
the relationship between the mind and the brain. His scientific career,
therefore, was directed toward revealing the psychophysical
relationship in terms of principles that would be rooted firmly in the
natural sciences and would not have to rely upon vague philosophical
or mystical ideas.
During his early career, Berger attempted to study psychophysical
relationships by making plethysmographic measurements of
changes in the brain circulation of patients with skull defects. In
plethysmography, an instrument is used to indicate and record by
tracings the variations in size of an organ or part of the body. Later,
Berger investigated temperature changes occurring in the human
brain during mental activity and the action of psychoactive drugs.
He became disillusioned, however, by the lack of psychophysical
understanding generated by these investigations.
Next, Berger turned to the study of the electrical activity of the
brain, and in the 1920’s he set out to search for the human electroencephalogram.
He believed that the electroencephalogram would finally
provide him with a physiological method capable of furnishing
insight into mental functions and their disturbances.

Electroencephalogram / 299
Berger made his first unsuccessful attempt at recording the electrical
activity of the brain in 1920, using the scalp of a bald medical
student. He then attempted to stimulate the cortex of patients with
skull defects by using a set of electrodes to apply an electrical current
to the skin covering the defect. The main purpose of these
stimulation experiments was to elicit subjective sensations. Berger
hoped that eliciting these sensations might give him some clue
about the nature of the relationship between the physiochemical
events produced by the electrical stimulus and the mental processes
revealed by the patients’ subjective experience. The availability
of many patients with skull defects—in whom the pulsating
surface of the brain was separated from the stimulating electrodes
by only a few millimeters of tissue—reactivated Berger’s interest
in recording the brain’s electrical activity.
Hans Berger
Hans Berger, the father of electroencephalography, was born
in Neuses bei Coburn, Germany, in 1873. He entered the University
of Jena in 1892 as a medical student and became an assistant
in the psychiatric clinic in 1897. In 1912 he was appointed
the clinic’s chief doctor and then its director and a university
professor of psychiatry. In 1919 he was chosen as rector of the
university.
Berger hoped to settle the long-standing philosophical question
about the brain and the mind by finding observable physical
processes that correlated with thought and feelings. He
started off by studying the blood circulation in the head and
brain temperature. Even though this work founded psychophysiology,
he failed to find objective evidence of subjective
states until he started examining fluctuations in the electrical
potential of the brain in 1924. His 1929 paper describing the
electroencephalograph later provided medicine with a basic diagnostic
tool, but the instrument proved to be a very confusing
probe of the human psyche for him. His colleagues in psychiatry
and medicine did not accept his relationships of physical
phenomena and mental states.
Berger retired as professor emeritus in 1938 and died three
years later in Jena.

300 / Electroencephalogram
Small, Tremulous Movements
Berger used several different instruments in trying to detect
brain waves, but all of them used a similar method of recording.
Electrical oscillations deflected a mirror upon which a light beam
was projected. The deflections of the light beam were proportional
to the magnitude of the electrical signals. The movement of the spot
of the light beam was recorded on photographic paper moving at a
speed no greater than 3 centimeters per second.
In July, 1924, Berger observed small, tremulous movements of
the instrument while recording from the skin overlying a bone defect
in a seventeen-year-old patient. In his first paper on the electroencephalogram,
Berger described this case briefly as his first successful
recording of an electroencephalogram. At the time of these
early studies, Berger already had used the term “electroencephalogram”
in his diary. Yet for several years he had doubts about the origin
of the electrical signals he recorded. As late as 1928, he almost
abandoned his electrical recording studies.
The publication of Berger’s first paper on the human encephalogram
in 1929 had little impact on the scientific world. It was either
ignored or regarded with open disbelief. At this time, even
when Berger himself was not completely free of doubts about the
validity of his findings, he managed to continue his work. He published
additional contributions to the study of the electroencephalogram
in a series of fourteen papers. As his research progressed,
Berger became increasingly confident and convinced of the significance
of his discovery.
Impact
The long-range impact of Berger’s work is incontestable. When
Berger published his last paper on the human encephalogram in
1938, the new approach to the study of brain function that he inaugurated
in 1929 had gathered momentum in many centers, both in
Europe and in the United States. As a result of his pioneering work,
a new diagnostic method had been introduced into medicine. Physiology
had acquired a new investigative tool. Clinical neurophysiology
had been liberated from its dependence upon the functional

anatomical approach, and electrophysiological exploration of complex
functions of the central nervous system had begun in earnest.
Berger’s work had finally received its well-deserved recognition.
Many of those who undertook the study of the electroencephalogram
were able to bring a far greater technical knowledge of
neurophysiology to bear upon the problems of the electrical activity
of the brain. Yet the community of neurological scientists has not
ceased to look with respect to the founder of electroencephalography,
who, despite overwhelming odds and isolation, opened a new
area of neurophysiology.
See also Amniocentesis; CAT scanner; Electrocardiogram; Mammography;
Nuclear magnetic resonance; Ultrasound; X-ray image
intensifier.
Further Reading
Electroencephalogram / 301
Barlow, John S. The Electroencephalogram: Its Patterns and Origins.
Cambridge, Mass.: MIT Press, 1993.
Berger, Hans. Hans Berger on the Electroencephalogram of Man. New
York: Elsevier, 1969.

302
Electron microscope
Electron microscope
The invention: A device for viewing extremely small objects that
uses electron beams and “electron lenses” instead of the light
rays and optical lenses used by ordinary microscopes.
The people behind the invention:
Ernst Ruska (1906-1988), a German engineer, researcher, and
inventor who shared the 1986 Nobel Prize in Physics
Hans Busch (1884-1973), a German physicist
Max Knoll (1897-1969), a German engineer and professor
Louis de Broglie (1892-1987), a French physicist who won the
1929 Nobel Prize in Physics
Reaching the Limit
The first electron microscope was constructed by Ernst Ruska
and Max Knoll in 1931. Scientists who look into the microscopic
world always demand microscopes of higher and higher resolution
(resolution is the ability of an optical instrument to distinguish
closely spaced objects). As early as 1834, George Airy, the eminent
British astronomer, theorized that there should be a natural limit to
the resolution of optical microscopes. In 1873, two Germans, Ernst
Abbe, cofounder of the Karl Zeiss Optical Works at Jena, and Hermann
von Helmholtz, the famous physicist and philosopher, independently
published papers on this issue. Both arrived at the same
conclusion as Airy: Light is limited by the size of its wavelength.
Specifically, light cannot resolve smaller than one-half the height of
its wavelength.
One solution to this limitation was to experiment with light, or
electromagnetic radiation, or shorter and shorter wavelengths.
At the beginning of the twentieth century, Joseph Edwin Barnard
experimented on microscopes using ultraviolet light. Such instruments,
however, only modestly improved the resolution. In
1912, German physicist Max von Laue considered using X rays.
At the time, however, it was hard to turn “X-ray microscopy” into
a physical reality. The wavelengths of X rays are exceedingly

short, but for the most part they are used to penetrate matter, not
to illuminate objects. It appeared that microscopes had reached
their limit.
Matter Waves
Electron microscope / 303
In a new microscopy, then, light—even electromagnetic radiation
in general—as the medium that traditionally carried image information,
had to be replaced by a new medium. In 1924, French
theoretical physicist Louis de Broglie advanced a startling hypothesis:
Matter on the scale of subatomic particles possesses wave
characteristics. De Broglie also concluded that the speed of lowmass
subatomic particles, such as electrons, is related to wavelength.
Specifically, higher speeds correspond to shorter wavelengths.
When Knoll and Ruska built the first electron microscope in 1931,
they had never heard about de Broglie’s “matter wave.” Ruska recollected
that when, in 1932, he and Knoll first learned about de
Broglie’s idea, he realized that those matter waves would have to be
many times shorter in wavelength than light waves.
The core component of the new instrument was the electron
beam, or “cathode ray,” as it was usually called then. The cathoderay
tube was invented in 1857 and was the source of a number of
discoveries, including X rays. In 1896, Olaf Kristian Birkeland, a
Norwegian scientist, after experimenting with the effect of parallel
magnetic fields on the electron beam of the cathode-ray tube, concluded
that cathode rays that are concentrated on a focal point by
means of a magnet are as effective as parallel light rays that are concentrated
by means of a lens.
From around 1910, German physicist Hans Busch was the leading
researcher in the field. In 1926, he published his theory on the
trajectories of electrons in magnetic fields. His conclusions confirmed
and expanded upon those of Birkeland. As a result, Busch
has been recognized as the founder of a new field later known
as “electron optics.” His theoretical study showed, among other
things, that the analogy between light and lenses on the one hand,
and electron beams and electromagnetic lenses, on the other hand,
was accurate.

304 / Electron microscope
Ernst Ruska
Ernst August Friedrich Ruska was born in 1906 in Heidelberg
to Professor Julius Ruska and his wife, Elisabeth. In 1925
he left home for the Technical College of Munich, moving two
years later to the Technical College of Berlin and gaining practical
training at nearby Siemens and Halsk Limited. During his
university days he became interested in vacuum tube technology
and worked at the Institute of High Voltage, participating
in the development of a high performance cathode ray oscilloscope.
His interests also lay with the theory and application of electron
optics. In 1929, as part of his graduate work, Ruska published
a proof of Hans Busch’s theory explaining possible lenslike
effects of a magnetic field on an electron stream, which led
to the invention of the polschuh lens. It formed the core of the
electron microscope that Ruska built with his mentor, Max
Kroll, in 1931.
Ruska completed his doctoral studies in 1934, but he had already
found work in industry, believing that further technical
development of electron microscopes was beyond the means of
university laboratories. He worked for Fernseh Limited from
1933 to 1937 and for Siemens from 1937 to 1955. Following
World War II he helped set up the Institute of Electron Optics
and worked in the Faculty of Medicine and Biology of the German
Academy of Sciences. He joined the Fritz Haber Institute
of the Max Planck Society in Berlin in 1949 and took over as director
of its Institute for Electron Microscopy in 1955, keeping
the position until he retired in 1974.
His life-long work with electron microscopy earned Ruska
half of the 1986 Nobel Prize in Physics. He died two years later.
To honor his memory, European manufacturers of electron microscopes
instituted the Ernst Ruska Prizes, one for researchers
of materials and optics and one for biomedical researchers.
Beginning in 1928, Ruska, as a graduate student at the Berlin Institute
of Technology, worked on refining Busch’s work. He found
that the energy of the electrons in the beam was not uniform. This
nonuniformity meant that the images of microscopic objects would
ultimately be fuzzy. Knoll and Ruska were able to work from the

ecognition of this problem to the design and materialization of a
concentrated electron “writing spot” and to the actual construction
of the electron microscope. By April, 1931, they had established a
technological landmark with the “first constructional realization of
an electron microscope.”
Impact
The world’s first electron microscope, which took its first photographic
record on April 7, 1931, was rudimentary. Its two-stage total
magnification was only sixteen times larger than the sample. Since
Ruska and Knoll’s creation, however, progress in electron microscopy
has been spectacular. Such an achievement is one of the prominent
examples that illustrate the historically unprecedented pace of
science and technology in the twentieth century.
In 1935, for the first time, the electron microscope surpassed
the optical microscope in resolution. The problem of damaging
the specimen by the heating effects of the electron beam proved
to be more difficult to resolve. In 1937, a team at the University of
Toronto constructed the first generally usable electron microscope.
In 1942, a group headed by James Hillier at the Radio Corporation
of America produced commercial transmission electron
microscopes. In 1939 and 1940, research papers on electron microscopes
began to appear in Sweden, Canada, the United States,
and Japan; from 1944 to 1947, papers appeared in Switzerland,
France, the Soviet Union, The Netherlands, and England. Following
research work in laboratories, commercial transmission electron
microscopes using magnetic lenses with short focal lengths
also appeared in these countries.
See also Cyclotron; Field ion microscope; Geiger counter; Mass
spectrograph; Neutrino detector; Scanning tunneling microscope;
Synchrocyclotron; Tevatron accelerator; Ultramicroscope.
Further Reading
Electron microscope / 305
Cline, Barbara Lovett. Men Who Made a New Physics: Physicists and
the Quantum Theory. Chicago: University of Chicago Press, 1987.

306 / Electron microscope
Hawkes, P. W. The Beginnings of Electron Microscopy. Orlando: Academic
Press, 1985.
Marton, Ladislaus. Early History of the Electron Microscope. 2d ed. San
Francisco: San Francisco Press, 1994.
Rasmussen, Nicolas. Picture Control: The Electron Microscope and the
Transformation of Biology in America, 1940-1960. Stanford, Calif.:
Stanford University Press, 1997.

Electronic synthesizer
Electronic synthesizer
The invention: Portable electronic device that both simulates the
sounds of acoustic instruments and creates entirely new sounds.
The person behind the invention:
Robert A. Moog (1934- ), an American physicist, engineer,
and inventor
From Harmonium to Synthesizer
307
The harmonium, or acoustic reed organ, is commonly viewed as
having evolved into the modern electronic synthesizer that can be
used to create many kinds of musical sounds, from the sounds of
single or combined acoustic musical instruments to entirely original
sounds. The first instrument to be called a synthesizer was patented
by the Frenchman J. A. Dereux in 1949. Dereux’s synthesizer, which
amplified the acoustic properties of harmoniums, led to the development
of the recording organ.
Next, several European and American inventors altered and
augmented the properties of such synthesizers. This stage of the
process was followed by the invention of electronic synthesizers,
which initially used electronically generated sounds to imitate
acoustic instruments. It was not long, however, before such synthesizers
were used to create sounds that could not be produced by any
other instrument. Among the early electronic synthesizers were
those made in Germany by Herbert Elmert and Robert Beyer in
1953, and the American Olsen-Belar synthesizers, which were developed
in 1954. Continual research produced better and better versions
of these large, complex electronic devices.
Portable synthesizers, which are often called “keyboards,” were
then developed for concert and home use. These instruments became
extremely popular, especially in rock music. In 1964, Robert A.
Moog, an electronics professor, created what are thought by many
to be the first portable synthesizers to be made available to the public.
Several other well-known portable synthesizers, such as ARP
and Buchla synthesizers, were also introduced at about the same

308 / Electronic synthesizer
time. Currently, many companies manufacture studio-quality synthesizers
of various types.
Synthesizer Components and Operation
Modern synthesizers make music electronically by building up
musical phrases via numerous electronic circuits and combining
those phrases to create musical compositions. In addition to duplicating
the sounds of many instruments, such synthesizers also enable
their users to create virtually any imaginable sound. Many
sounds have been created on synthesizers that could not have been
created in any other way.
Synthesizers use sound-processing and sound-control equipment
that controls “white noise” audio generators and oscillator circuits.
This equipment can be manipulated to produce a huge variety of
sound frequencies and frequency mixtures in the same way that a
beam of white light can be manipulated to produce a particular
color or mixture of colors.
Once the desired products of a synthesizer’s noise generator and
oscillators are produced, percussive sounds that contain all or many
audio frequencies are mixed with many chosen individual sounds
and altered by using various electronic processing components. The
better the quality of the synthesizer, the more processing components
it will possess. Among these components are sound amplifiers,
sound mixers, sound filters, reverberators, and sound combination
devices.
Sound amplifiers are voltage-controlled devices that change the
dynamic characteristics of any given sound made by a synthesizer.
Sound mixers make it possible to combine and blend two or more
manufactured sounds while controlling their relative volumes.
Sound filters affect the frequency content of sound mixtures by increasing
or decreasing the amplitude of the sound frequencies
within particular frequency ranges, which are called “bands.”
Sound filters can be either band-pass filters or band-reject filters.
They operate by increasing or decreasing the amplitudes of sound
frequencies within given ranges (such as treble or bass). Reverberators
(or “reverb” units) produce artificial echoes that can have significant
musical effects. There are also many other varieties of sound-

Robert Moog
Electronic synthesizer / 309
Robert Moog, born in 1934, grew up in the Queens borough
of New York City, a tough area for a brainy kid. To avoid the
bullies who picked on him because he was a nerd, Moog spent a
lot of time helping his father with his hobby, electronics. At
fourteen, he built his own theremin, an eerie-sounding forerunner
of electric instruments.
Moog’s mother, meanwhile, force-fed him piano lessons. He
liked science better and majored in physics at Queens College
and then Cornell University, but he did not forget the music.
While in college, he designed a kit for making theremins and
advertised it, selling enough of them to run up a sizable bankroll.
Also while in college, Moog, acting on a suggestion from a
composer, put together the first easy-to-play electronic synthesizer.
Other music synthesizers already existed, but they were
large, complex, and expensive—suitable only for recording studios.
When Moog unveiled his synthesizer in 1965, it was portable,
sold for one-tenth the price, and gave musicians virtually
an orchestra at their fingertips. It became a stage instrument.
Walter Carlos used a Moog synthesizer in 1969 for his album
Switched-on Bach, electronic renditions of Johann Sebastian Bach’s
concertos. It was a hit and won a Grammy award. The album
made Moog and his new instrument famous. Its reputation
grew when the Beatles used it for “Because” on Abbey Road and
Carlos recorded the score for Stanley Kubrick’s classic movie A
Clockwork Orange on a Moog. With the introduction of the even
more portable Minimoog, the popularity of synthesizers soared,
especially among rock musicians but also in jazz and other
styles.
Moog sold his company and moved to North Carolina in
1978. There he started another company, Big Briar, devoted to
designing special instruments, such as a keyboard that can be
played with as much expressive subtlety as a violin and an interactive
piano.
processing elements, among them sound-envelope generators,
spatial locators, and frequency shifters. Ultimately, the soundcombination
devices put together the results of the various groups
of audio generating and processing elements, shaping the sound
that has been created into its final form.

310 / Electronic synthesizer
A variety of control elements are used to integrate the operation
of synthesizers. Most common is the keyboard, which provides the
name most often used for portable electronic synthesizers. Portable
synthesizer keyboards are most often pressure-sensitive devices
(meaning that the harder one presses the key, the louder the resulting
sound will be) that resemble the black-and-white keyboards of
more conventional musical instruments such as the piano and the
organ. These synthesizer keyboards produce two simultaneous outputs:
control voltages that govern the pitches of oscillators, and timing
pulses that sustain synthesizer responses for as long as a particular
key is depressed.
Unseen but present are the integrated voltage controls that control
overall signal generation and processing. In addition to voltage
controls and keyboards, synthesizers contain buttons and other
switches that can transpose their sound ranges and other qualities.
Using the appropriate buttons or switches makes it possible for a
single synthesizer to imitate different instruments—or groups of instruments—at
different times. Other synthesizer control elements
include sample-and-hold devices and random voltage sources that
make it possible to sustain particular musical effects and to add various
effects to the music that is being played, respectively.
Electronic synthesizers are complex and flexible instruments.
The various types and models of synthesizers make it possible to
produce many different kinds of music, and many musicians use a
variety of keyboards to give them great flexibility in performing
and recording.
Impact
The development and wide dissemination of studio and portable
synthesizers has led to their frequent use to combine the sound
properties of various musical instruments; a single musician can
thus produce, inexpensively and with a single instrument, sound
combinations that previously could have been produced only by a
large number of musicians playing various instruments. (Understandably,
many players of acoustic instruments have been upset by
this development, since it means that they are hired to play less often
than they were before synthesizers were developed.) Another

consequence of synthesizer use has been the development of entirely
original varieties of sound, although this area has been less
thoroughly explored, for commercial reasons. The development of
synthesizers has also led to the design of other new electronic music-making
techniques and to the development of new electronic
musical instruments.
Opinions about synthesizers vary from person to person—and,
in the case of certain illustrious musicians, from time to time. One
well-known musician initially proposed that electronic synthesizers
would replace many or all conventional instruments, particularly
pianos. Two decades later, though, this same musician noted
that not even the best modern synthesizers could match the quality
of sound produced by pianos made by manufacturers such as
Steinway and Baldwin.
See also Broadcaster guitar; Cassette recording; Compact disc;
Dolby noise reduction; Transistor.
Further Reading
Electronic synthesizer / 311
Hopkin, Bart. Gravikords, Whirlies and Pyrophones: Experimental Musical
Instruments. Roslyn, N.Y.: Ellipsis Arts, 1996.
Koener, Brendan I.. “Back to Music’s Future.” U.S. News & World Report
122, no. 8 (March 3, 1997).
Nunziata, Susan. “Moog Keyboard Offers Human Touch.” Billboard
104, no. 7 (February 15, 1992).
Shapiro, Peter. Modulations: A History of Electronic Music: Throbbing
Words on Sound. New York: Caipirinha Productions, 2000.

312
ENIAC computer
ENIAC computer
The invention: The first general-purpose electronic digital computer.
The people behind the invention:
John Presper Eckert (1919-1995), an electrical engineer
John William Mauchly (1907-1980), a physicist, engineer, and
professor
John von Neumann (1903-1957), a Hungarian American
mathematician, physicist, and logician
Herman Heine Goldstine (1913- ), an army mathematician
Arthur Walter Burks (1915- ), a philosopher, engineer, and
professor
John Vincent Atanasoff (1903-1995), a mathematician and
physicist
A Technological Revolution
The Electronic Numerical Integrator and Calculator (ENIAC) was
the first general-purpose electronic digital computer. By demonstrating
the feasibility and value of electronic digital computation, it initiated
the computer revolution. The ENIAC was developed during
World War II (1939-1945) at the Moore School of Electrical Engineering
by a team headed by John William Mauchly and John Presper
Eckert, who were working on behalf of the U.S. Ordnance Ballistic
Research Laboratory (BRL) at the Aberdeen Proving Ground in
Maryland. Early in the war, the BRL’s need to generate ballistic firing
tables already far outstripped the combined abilities of the available
differential analyzers and teams of human computers.
In 1941, Mauchly had seen the special-purpose electronic computer
developed by John Vincent Atanasoff to solve sets of linear
equations. Atanasoff’s computer was severely limited in scope and
was never fully completed. The functioning prototype, however,
helped convince Mauchly of the feasibility of electronic digital computation
and so led to Mauchly’s formal proposal in April, 1943, to
develop the general-purpose ENIAC. The BRL, in desperate need of
computational help, agreed to fund the project, with Lieutenant

Herman Heine Goldstine overseeing it for the U.S. Army.
This first substantial electronic computer was designed, built,
and debugged within two and one-half years. Even given the highly
talented team, it could be done only by taking as few design risks as
possible. The ENIAC ended up as an electronic version of prior
computers: Its functional organization was similar to that of the
differential analyzer, while it was programmed via a plugboard
(which was something like a telephone switchboard), much like the
earlier electromechanical calculators made by the International Business
Machines (IBM) Corporation. Another consequence was that
the internal representation of numbers was decimal rather than the
now-standard binary, since the familiar electromechanical computers
used decimal digits.
Although the ENIAC was completed only after the end of the
war, it was used primarily for military purposes. In fact, the first
production run on the system was a two-month calculation needed
for the design of the hydrogen bomb. John von Neumann, working
as a consultant to both the Los Alamos Scientific Laboratory and the
ENIAC project, arranged for the production run immediately prior
to ENIAC’s formal dedication in 1946.
A Very Fast Machine
ENIAC computer / 313
The ENIAC was an impressive machine: It contained 18,000 vacuum
tubes, weighed 27 metric tons, and occupied a large room. The
final cost to the U.S. Army was about $486,000. For this price, the
army received a machine that computed up to a thousand times
faster than its electromechanical precursors; for example, addition
and subtraction required only 200 microseconds (200 millionths of a
second). At its dedication ceremony, the ENIAC was fast enough to
calculate a fired shell’s trajectory faster than the shell itself took to
reach its target.
The machine also was much more complex than any predecessor
and employed a risky new technology in vacuum tubes; this caused
much concern about its potential reliability. In response to this concern,
Eckert, the lead engineer, imposed strict safety factors on all
components, requiring the design to use components at a level well
below the manufacturers’ specified limits. The result was a machine

314 / ENIAC computer
that ran for as long as three days without a hardware malfunction.
Programming the ENIAC was effected by setting switches and
physically connecting accumulators, function tables (a kind of manually
set read-only memory), and control units. Connections were
made via cables running between plugboards. This was a laborious
and error-prone process, often requiring a one-day set time.
The team recognized this problem, and in early 1945, Eckert,
Mauchly, and Neumann worked on the design of a new machine.
Their basic idea was to treat both program and data in the same way,
and in particular to store them in the same high-speed memory; in
other words, they planned to produce a stored-program computer.
Neumann described and explained this design in his “First Draft of
a Report on the EDVAC” (EDVAC is an acronym for Electronic Discrete
Variable Automatic Computer). In his report, Neumann contributed
new design techniques and provided the first general, comprehensive
description of the stored-program architecture.
After the delivery of the ENIAC, Neumann suggested that it
could be wired up so that a set of instructions would be permanently
available and could be selected by entries in the function tables.
Engineers implemented the idea, providing sixty instructions
that could be invoked from the programs stored into the function tables.
Despite slowing down the computer’s calculations, this technique
was so superior to plugboard programming that it was used
exclusively thereafter. In this way, the ENIAC was converted into a
kind of primitive stored-program computer.
Impact
The ENIAC’s electronic speed and the stored-program design of
the EDVAC posed a serious engineering challenge: to produce a
computer memory that would be large, inexpensive, and fast. Without
such fast memories, the electronic control logic would spend
most of its time idling. Vacuum tubes themselves (used in the control)
were not an effective answer because of their large power requirements
and heat generation.
The EDVAC design draft proposed using mercury delay lines,
which had been used earlier in radars. These delay lines converted
an electronic signal into a slower acoustic signal in a mercury solu-

tion; for continuous storage, the signal picked up at the other end
was regenerated and sent back into the mercury. Maurice Vincent
Wilkes at the University of Cambridge was the first to complete
such a system, in May, 1949. One month earlier, Frederick Calland
Williams and Tom Kilburn at Manchester University had brought
their prototype computer into operation, which used cathode-ray
tubes (CRTs) for its main storage. Thus, England took an early lead
in developing computing systems, largely because of a more immediate
practical design approach.
In the meantime, Eckert and Mauchly formed the Electronic Control
Company (later the Eckert-Mauchly Computer Corporation).
They produced the Binary Automatic Computer (BINAC) in 1949
and the Universal Automatic Computer (UNIVAC) I in 1951; both
machines used mercury storage.
The memory problem that the ENIAC introduced was finally resolved
with the invention of the magnetic core in the early 1950’s.
Core memory was installed on the ENIAC and soon on all new machines.
The ENIAC continued in operation until October, 1955,
when parts of it were retired to the Smithsonian Institution. The
ENIAC proved the viability of digital electronics and led directly to
the development of stored-program computers. Its impact can be
seen in every modern digital computer.
See also Apple II computer; BINAC computer; Colossus computer;
IBM Model 1401 computer; Personal computer; Supercomputer;
UNIVAC computer.
Further Reading
ENIAC computer / 315
Burks, Alice R., and Arthur W. Burks. The First Electronic Computer:
The Atanasoff Story. Ann Arbor: University of Michigan Press,
1990.
McCarney, Scott. ENIAC: The Triumphs and Tragedies of the World’s
First Computer. New York: Berkley Books, 2001.
Slater, Robert. Portraits in Silicon. Cambridge, Mass.: MIT Press,
1989.
Stern, Nancy B. From ENIAC to UNIVAC: An Appraisal of the Eckert-
Mauchly Computers. Bedford, Mass.: Digital Press, 1981.

316
Fax machine
Fax machine
The invention: Originally known as the “facsimile machine,” a
machine that converts written and printed images into electrical
signals that can be sent via telephone, computer, or radio.
The person behind the invention:
Alexander Bain (1818-1903), a Scottish inventor
Sending Images
The invention of the telegraph and telephone during the latter
half of the nineteenth century gave people the ability to send information
quickly over long distances. With the invention of radio and
television technologies, voices and moving pictures could be seen
around the world as well. Oddly, however, the facsimile process—
which involves the transmission of pictures, documents, or other
physical data over distance—predates all these modern devices,
since a simple facsimile apparatus (usually called a fax machine)
was patented in 1843 by Alexander Bain. This early device used a
pendulum to synchronize the transmitting and receiving units; it
did not convert the image into an electrical format, however, and it
was quite crude and impractical. Nevertheless, it reflected the desire
to send images over long distances, which remained a technological
goal for more than a century.
Facsimile machines developed in the period around 1930 enabled
news services to provide newspapers around the world with
pictures for publication. It was not until the 1970’s, however, that
technological advances made small fax machines available for everyday
office use.
Scanning Images
Both the fax machines of the 1930’s and those of today operate on
the basis of the same principle: scanning. In early machines, an image
(a document or a picture) was attached to a roller, placed in the
fax machine, and rotated at a slow and fixed speed (which must be

Fax machine / 317
the same at each end of the link) in a bright light. Light from the image
was reflected from the document in varying degrees, since dark
areas reflect less light than lighter areas do. A lens moved across the
page one line at a time, concentrating and directing the reflected
light to a photoelectric tube. This tube would respond to the change
in light level by varying its electric output, thus converting the image
into an output signal whose intensity varied with the changing
light and dark spots of the image. Much like the signal from a microphone
or television camera, this modulated (varying) wave could
then be broadcast by radio or sent over telephone lines to a receiver
that performed a reverse function. At the receiving end, a light bulb
was made to vary its intensity to match the varying intensity of the
incoming signal. The output of the light bulb was concentrated
through a lens onto photographically sensitive paper, thus re-creating
the original image as the paper was rotated.
Early fax machines were bulky and often difficult to operate.
Advances in semiconductor and computer technology in the 1970’s,
however, made the goal of creating an easy-to-use and inexpensive
fax machine realistic. Instead of a photoelectric tube that consumes
a relatively large amount of electrical power, a row of small photodiode
semiconductors is used to measure light intensity. Instead of a
power-consuming light source, low-power light-emitting diodes
(LEDs) are used. Some 1,728 light-sensitive diodes are placed in a
row, and the image to be scanned is passed over them one line at a
time. Each diode registers either a dark or a light portion of the image.
As each diode is checked in sequence, it produces a signal for
one picture element, also known as a “pixel” or “pel.” Because
many diodes are used, there is no need for a focusing lens; the diode
bar is as wide as the page being scanned, and each pixel represents a
portion of a line on that page.
Since most fax transmissions take place over public telephone
system lines, the signal from the photodiodes is transmitted by
means of a built-in computer modem in much the same format that
computers use to transmit data over telephone lines. The receiving
fax uses its modem to convert the audible signal into a sequence that
varies in intensity in proportion to the original signal. This varying
signal is then sent in proper sequence to a row of 1,728 small wires
over which a chemically treated paper is passed. As each wire re-

318 / Fax machine
ceives a signal that represents a black portion of the scanned image,
the wire heats and, in contact with the paper, produces a black dot
that corresponds to the transmitted pixel. As the page is passed over
these wires one line at a time, the original image is re-created.
Consequences
The fax machine has long been in use in many commercial and
scientific fields. Weather data in the form of pictures are transmitted
from orbiting satellites to ground stations; newspapers receive photographs
from international news sources via fax; and, using a very
expensive but very high-quality fax device, newspapers and magazines
are able to transmit full-size proof copies of each edition to
printers thousands of miles away so that a publication edited in one
country can reach newsstands around the world quickly.
With the technological advances that have been made in recent
years, however, fax transmission has become a part of everyday life,
particularly in business and research environments. The ability to
send quickly a copy of a letter, document, or report over thousands
of miles means that information can be shared in a matter of minutes
rather than in a matter of days. In fields such as advertising and
architecture, it is often necessary to send pictures or drawings to remote
sites. Indeed, the fax machine has played an important role in
providing information to distant observers of political unrest when
other sources of information (such as radio, television, and newspapers)
are shut down.
In fact, there has been a natural coupling of computers, modems,
and fax devices. Since modern faxes are sent as computer data over
phone lines, specialized and inexpensive modems (which allow
two computers to share data) have been developed that allow any
computer user to send and receive faxes without bulky machines.
For example, a document—including drawings, pictures, or graphics
of some kind—is created in a computer and transmitted directly
to another fax machine. That computer can also receive a fax transmission
and either display it on the computer’s screen or print it on
the local printer. Since fax technology is now within the reach of almost
anyone who is interested in using it, there is little doubt that it
will continue to grow in popularity.

See also Communications satellite; Instant photography; Internet;
Personal computer; Xerography.
Further Reading
Fax machine / 319
Bain, Alexander, and Leslie William Davidson. Autobiography. New
York: Longmans, Green, 1973.
Cullen, Scott. “Telecommunications in the Office.” Office Systems 16,
no. 12 (December, 1999).
Holtzmann, Gerald J. “Just the Fax.” Inc. 20, no. 13 (September 15,
1998).
Hunkin, Tim. “Just Give Me the Fax.” New Scientist 137, no. 1860
(February 13, 1993).

320
Fiber-optics
Fiber-optics
The invention: The application of glass fibers to electronic communications
and other fields to carry large volumes of information
quickly, smoothly, and cheaply over great distances.
The people behind the invention:
Samuel F. B. Morse (1791-1872), the American artist and
inventor who developed the electromagnetic telegraph
system
Alexander Graham Bell (1847-1922), the Scottish American
inventor and educator who invented the telephone and the
photophone
Theodore H. Maiman (1927- ), the American physicist and
engineer who invented the solid-state laser
Charles K. Kao (1933- ), a Chinese-born electrical engineer
Zhores I. Alferov (1930- ), a Russian physicist and
mathematician
The Singing Sun
In 1844, Samuel F. B. Morse, inventor of the telegraph, sent his famous
message, “What hath God wrought?” by electrical impulses
traveling at the speed of light over a 66-kilometer telegraph wire
strung between Washington, D.C., and Baltimore. Ever since that
day, scientists have worked to find faster, less expensive, and more
efficient ways to convey information over great distances.
At first, the telegraph was used to report stock-market prices and
the results of political elections. The telegraph was quite important
in the American Civil War (1861-1865). The first transcontinental
telegraph message was sent by Stephen J. Field, chief justice of the
California Supreme Court, to U.S. president Abraham Lincoln on
October 24, 1861. The message declared that California would remain
loyal to the Union. By 1866, telegraph lines had reached all
across the North American continent and a telegraph cable had
been laid beneath the Atlantic Ocean to link the Old World with the
New World.

Zhores I. Alferov
Fiber-optics / 321
To create a telephone system that transmitted with light,
perfecting fiber-optic cables was only half the solution. There
also had to be a small, reliable, energy-efficient light source. In
the 1960’s engineers realized that lasers were the best candidate.
However, early gas lasers were bulky, and semiconductor
lasers, while small, were temperamental and had to be cooled
in liquid nitrogen. Nevertheless, the race was on to devise a
semiconductor laser that produced a continuous beam and did
not need to be cooled. The race was between a Bell Labs team in
the United States and a Russian team led by Zhores I. Alferov,
neither of which knew much about the other.
Alferov was born in 1930 in Vitebsk, Byelorussia, then part
of the Soviet Union. He earned a degree in electronics from the
V. I. Ulyanov (Lenin) Electrotechnical Institute in Leningrad
(now St. Petersburg). As part of his graduate studies, he became
a researcher at the A. F. Ioffe Physico-Technical Institute in the
same city, receiving a doctorate in physics and mathematics in
1970. By then he was one of the world’s leading experts in semiconductor
lasers.
Alferov found that he could improve the laser’s performance
by sandwiching very thin layers of gallium arsenide and
metal, insulated in silicon, in such a way that electrons flowed
only along a 0.03 millimeter strip, producing light in the process.
This double heterojunction narrow-stripe laser was the answer,
producing a steady beam at room temperature. Alferov
published his results a month before the American team came
up with almost precisely the same solution.
The question of who was first was not settled until much
later, during which time both Bell Labs and Alferov’s institute
went on to further refinements of the technology. Alferov rose
to become a dean at the St. Petersburg Technical University and
vice-president of the Russian Academy of Sciences. In 2000 he
shared the Nobel Prize in Physics.
Another American inventor made the leap from the telegraph to
the telephone. Alexander Graham Bell, a teacher of the deaf, was interested
in the physical way speech works. In 1875, he started experimenting
with ways to transmit sound vibrations electrically. He realized
that an electrical current could be adjusted to resemble the

322 / Fiber-optics
vibrations of speech. Bell patented his invention on March 7, 1876.
On July 9, 1877, he founded the Bell Telephone Company.
In 1880, Bell invented a device called the “photophone.” He used
it to demonstrate that speech could be transmitted on a beam of
light. Light is a form of electromagnetic energy. It travels in a vibrating
wave. When the amplitude (height) of the wave is adjusted, a
light beam can be made to carry messages. Bell’s invention included
a thin mirrored disk that converted sound waves directly into a
beam of light. At the receiving end, a selenium resistor connected to
a headphone converted the light back into sound. “I have heard a
ray of sun laugh and cough and sing,” Bell wrote of his invention.
Although Bell proved that he could transmit speech over distances
of several hundred meters with the photophone, the device
was awkward and unreliable, and it never became popular as the
telephone did. Not until one hundred years later did researchers find
important practical uses for Bell’s idea of talking on a beam of light.
Two other major discoveries needed to be made first: development
of the laser and of high-purity glass. Theodore H. Maiman, an
American physicist and electrical engineer at Hughes Research Laboratories
in Malibu, California, built the first laser. The laser produces
an intense, narrowly focused beam of light that can be adjusted to
carry huge amounts of information. The word itself is an acronym for
light amplification by the stimulated emission of radiation.
It soon became clear, though, that even bright laser light can be
broken up and absorbed by smog, fog, rain, and snow. So in 1966,
Charles K. Kao, an electrical engineer at the Standard Telecommunications
Laboratories in England, suggested that glass fibers could
be used to transmit message-carrying beams of laser light without
disruption from weather.
Fiber Optics Are Tested
Optical glass fiber is made from common materials, mostly silica,
soda, and lime. The inside of a delicate silica glass tube is coated
with a hundred or more layers of extremely thin glass. The tube is
then heated to 2,000 degrees Celsius and collapsed into a thin glass
rod, or preform. The preform is then pulled into thin strands of fiber.
The fibers are coated with plastic to protect them from being nicked
or scratched, and then they are covered in flexible cable.

Fiber-optics / 323
The earliest glass fibers
contained many impurities
and defects, so they did not
carry light well. Signal repeaters
were needed every
few meters to energize
(amplify) the fading pulses
of light. In 1970, however,
researchers at the Corning
Glass Works in New York
developed a fiber pure
enough to carry light at
Fiber optic strands. (PhotoDisc)
least one kilometer without
amplification.
The telephone industry
quickly became involved in the new fiber-optics technology. Researchers
believed that a bundle of optical fibers as thin as a pencil
could carry several hundred telephone calls at the same time. Optical
fibers were first tested by telephone companies in big cities,
where the great volume of calls often overloaded standard underground
phone lines.
On May 11, 1977, American Telephone & Telegraph Company
(AT&T), along with Illinois Bell Telephone, Western Electric, and
Bell Telephone Laboratories, began the first commercial test of fiberoptics
telecommunications in downtown Chicago. The system consisted
of a 2.4-kilometer cable laid beneath city streets. The cable,
only 1.3 centimeters in diameter, linked an office building in the
downtown business district with two telephone exchange centers.
Voice and video signals were coded into pulses of laser light and
transmitted through the hair-thin glass fibers. The tests showed that
a single pair of fibers could carry nearly six hundred telephone conversations
at once very reliably and at a reasonable cost.
Six years later, in October, 1983, Bell Laboratories succeeded in
transmitting the equivalent of six thousand telephone signals through
an optical fiber cable that was 161 kilometers long. Since that time,
countries all over the world, from England to Indonesia, have developed
optical communications systems.

324 / Fiber-optics
Consequences
Fiber optics has had a great impact on telecommunications. A single
fiber can now carry thousands of conversations with no electrical
interference. These fibers are less expensive, weigh less, and take up
much less space than copper wire. As a result, people can carry on
conversations over long distances without static and at a low cost.
One of the first uses of fiber optics and perhaps its best-known
application is the fiberscope, a medical instrument that permits internal
examination of the human body without surgery or X-ray
techniques. The fiberscope, or endoscope, consists of two fiber
bundles. One of the fiber bundles transmits bright light into the patient,
while the other conveys a color image back to the eye of the
physician. The fiberscope has been used to look for ulcers, cancer,
and polyps in the stomach, intestine, and esophagus of humans.
Medical instruments, such as forceps, can be attached to the fiberscope,
allowing the physician to perform a range of medical procedures,
such as clearing a blocked windpipe or cutting precancerous
polyps from the colon.
See also Cell phone; Community antenna television; Communications
satellite; FM radio; Laser; Long-distance radiotelephony;
Long-distance telephone; Telephone switching.
Further Reading
Carey, John, and Neil Gross. “The Light Fantastic: Optoelectronics
May Revolutionize Computers—and a Lot More.” Business Week
(May 10, 1993).
Free, John. “Fiber Optics Head for Home.” Popular Science 238
(March, 1991).
Hecht, Jeff. City of Light: The Story of Fiber Optics. Oxford: Oxford
University Press, 1999.
Paul, Noel C. “Laying Down the Line with Huge Projects to Circle
the Globe in Fiber Optic Cable.” Christian Science Monitor (March
29, 2001).
Shinal, John G., with Timothy J. Mullaney. “At the Speed of Light.”
Business Week (October 9, 2000).

Field ion microscope
Field ion microscope
The invention: A microscope that uses ions formed in high-voltage
electric fields to view atoms on metal surfaces.
The people behind the invention:
Erwin Wilhelm Müller (1911-1977), a physicist, engineer, and
research professor
J. Robert Oppenheimer (1904-1967), an American physicist
To See Beneath the Surface
325
In the early twentieth century, developments in physics, especially
quantum mechanics, paved the way for the application of
new theoretical and experimental knowledge to the problem of
viewing the atomic structure of metal surfaces. Of primary importance
were American physicist George Gamow’s 1928 theoretical
explanation of the field emission of electrons by quantum mechanical
means and J. Robert Oppenheimer’s 1928 prediction of the
quantum mechanical ionization of hydrogen in a strong electric
field.
In 1936, Erwin Wilhelm Müller developed his field emission microscope,
the first in a series of instruments that would exploit
these developments. It was to be the first instrument to view
atomic structures—although not the individual atoms themselves—
directly. Müller’s subsequent field ion microscope utilized the
same basic concepts used in the field emission microscope yet
proved to be a much more powerful and versatile instrument. By
1956, Müller’s invention allowed him to view the crystal lattice
structure of metals in atomic detail; it actually showed the constituent
atoms.
The field emission and field ion microscopes make it possible to
view the atomic surface structures of metals on fluorescent screens.
The field ion microscope is the direct descendant of the field emission
microscope. In the case of the field emission microscope, the
images are projected by electrons emitted directly from the tip of a
metal needle, which constitutes the specimen under investigation.

326 / Field ion microscope
These electrons produce an image of the atomic lattice structure of
the needle’s surface. The needle serves as the electron-donating
electrode in a vacuum tube, also known as the “cathode.” A fluorescent
screen that serves as the electron-receiving electrode, or “anode,”
is placed opposite the needle. When sufficient electrical voltage
is applied across the cathode and anode, the needle tip emits
electrons, which strike the screen. The image produced on the
screen is a projection of the electron source—the needle surface’s
atomic lattice structure.
Müller studied the effect of needle shape on the performance of
the microscope throughout much of 1937. When the needles had
been properly shaped, Müller was able to realize magnifications of
up to 1 million times. This magnification allowed Müller to view
what he called “maps” of the atomic crystal structure of metals,
since the needles were so small that they were often composed of
only one simple crystal of the material. While the magnification
may have been great, however, the resolution of the instrument was
severely limited by the physics of emitted electrons, which caused
the images Müller obtained to be blurred.
Improving the View
In 1943, while working in Berlin, Müller realized that the resolution
of the field emission microscope was limited by two factors.
The electron velocity, a particle property, was extremely high and
uncontrollably random, causing the micrographic images to be
blurred. In addition, the electrons had an unsatisfactorily high wavelength.
When Müller combined these two factors, he was able to determine
that the field emission microscope could never depict single
atoms; it was a physical impossibility for it to distinguish one
atom from another.
By 1951, this limitation led him to develop the technology behind
the field ion microscope. In 1952, Müller moved to the United States
and founded the Pennsylvania State University Field Emission Laboratory.
He perfected the field ion microscope between 1952 and
1956.
The field ion microscope utilized positive ions instead of electrons
to create the atomic surface images on the fluorescent screen.

Erwin Müller
Field ion microscope / 327
Erwin Müller’s scientific goal was to see an individual atom,
and to that purpose he invented ever more powerful microscopes.
He was born in Berlin, Germany, in 1911 and attended
the city’s Technische Hochschule, earning a diploma in engineering
in 1935 and a doctorate in physics in 1936.
Following his studies he worked as an industrial researcher.
Still a neophyte scientist, he discovered the principle of the field
emission microscope and was able to produce an image of a
structure only two nanometers in diameter on the surface of a
cathode. In 1941 Müller discovered field desorption by reversing
the polarity of the electron emitter at very low temperatures
so that surface atoms evaporated in the electric field. In 1947 he
left industry and began an academic career, teaching physical
chemistry at the Altenburg Engineering School. The following
year he was appointed a department head at the Fritz Haber Institute.
While there, he found that by having a cathode absorb
gas ions and then re-emit them he could produce greater magnification.
In 1952 Müller became a professor at Pennsylvania State
University. Applying the new field-ion emission principle, he
was able to achieve his goal, images of individual atoms, in
1956. Almost immediately chemists and physicists adopted the
field-ion microscope to conduct basic research concerning the
underlying behavior of field ionization and interactions among
absorbed atoms. He further aided such research by coupling a
field-ion microscope and mass spectrometer, calling the combination
an atom-probe field-ion microscope; it could both magnify
and chemically analyze atoms.
Müller died in 1977. He received the National Medal of Science
posthumously, one of many honors for his contributions to
microscopy.
When an easily ionized gas—at first hydrogen, but usually helium,
neon, or argon—was introduced into the evacuated tube, the emitted
electrons ionized the gas atoms, creating a stream of positively
charged particles, much as Oppenheimer had predicted in 1928.
Müller’s use of positive ions circumvented one of the resolution
problems inherent in the use of imaging electrons. Like the electrons,
however, the positive ions traversed the tube with unpredict-

328 / Field ion microscope
ably random velocities. Müller eliminated this problem by cryogenically
cooling the needle tip with a supercooled liquefied gas such as
nitrogen or hydrogen.
By 1956, Müller had perfected the means of supplying imaging
positive ions by filling the vacuum tube with an extremely small
quantity of an inert gas such as helium, neon, or argon. By using
such a gas, Müller was assured that no chemical reaction would occur
between the needle tip and the gas; any such reaction would alter
the surface atomic structure of the needle and thus alter the resulting
microscopic image. The imaging ions allowed the field ion
microscope to image the emitter surface to a resolution of between
two and three angstroms, making it ten times more accurate than its
close relative, the field emission microscope.
Consequences
The immediate impact of the field ion microscope was its influence
on the study of metallic surfaces. It is a well-known fact of materials
science that the physical properties of metals are influenced
by the imperfections in their constituent lattice structures. It was not
possible to view the atomic structure of the lattice, and thus the finest
detail of any imperfection, until the field ion microscope was developed.
The field ion microscope is the only instrument powerful
enough to view the structural flaws of metal specimens in atomic
detail.
Although the instrument may be extremely powerful, the extremely
large electrical fields required in the imaging process preclude
the instrument’s application to all but the heartiest of metallic
specimens. The field strength of 500 million volts per centimeter
exerts an average stress on metal specimens in the range of almost
1 ton per square millimeter. Metals such as iron and platinum can
withstand this strain because of the shape of the needles into which
they are formed. Yet this limitation of the instrument makes it extremely
difficult to examine biological materials, which cannot withstand
the amount of stress that metals can. A practical by-product in
the study of field ionization—field evaporation—eventually permitted
scientists to view large biological molecules.
Field evaporation also allowed surface scientists to view the

atomic structures of biological molecules. By embedding molecules
such as phthalocyanine within the metal needle, scientists have
been able to view the atomic structures of large biological molecules
by field evaporating much of the surrounding metal until the biological
material remains at the needle’s surface.
See also Cyclotron; Electron microscope; Mass spectrograph;
Neutrino detector; Scanning tunneling microscope; Sonar; Synchrocyclotron;
Tevatron accelerator; Ultramicroscope.
Further Reading
Field ion microscope / 329
Gibson, J. M. “Tools for Probing ‘Atomic’ Action.” IEEE Spectrum 22,
no. 12 (December, 1985).
Kunetka, James W. Oppenheimer: The Years of Risk. Englewood Cliffs,
N.J.: Prentice-Hall, 1982.
Schweber, Silvan S. In the Shadow of the Bomb: Bethe, Oppenheimer, and
the Moral Responsibility of the Scientist. Princeton, N.J.: Princeton
University Press, 2000.
Tsong, Tien Tzou. Atom-Probe Field Ion Microscopy: Field Ion Emission
and Surfaces and Interfaces at Atomic Resolution. New York: Cambridge
University Press, 1990.

330
Floppy disk
Floppy disk
The invention: Inexpensive magnetic medium for storing and
moving computer data.
The people behind the invention:
Andrew D. Booth (1918- ), an English inventor who
developed paper disks as a storage medium
Reynold B. Johnson (1906-1998), a design engineer at IBM’s
research facility who oversaw development of magnetic disk
storage devices
Alan Shugart (1930- ), an engineer at IBM’s research
laboratory who first developed the floppy disk as a means of
mass storage for mainframe computers
First Tries
When the International Business Machines (IBM) Corporation
decided to concentrate on the development of computers for business
use in the 1950’s, it faced a problem that had troubled the earliest
computer designers: how to store data reliably and inexpensively.
In the early days of computers (the early 1940’s), a number of
ideas were tried. The English inventor Andrew D. Booth produced
spinning paper disks on which he stored data by means of punched
holes, only to abandon the idea because of the insurmountable engineering
problems he foresaw.
The next step was “punched” cards, an idea first used when the
French inventor Joseph-Marie Jacquard invented an automatic weaving
loom for which patterns were stored in pasteboard cards. The
idea was refined by the English mathematician and inventor Charles
Babbage for use in his “analytical engine,” an attempt to build a kind
of computing machine. Although it was simple and reliable, it was
not fast enough, nor did it store enough data, to be truly practical.
The Ampex Corporation demonstrated its first magnetic audiotape
recorder after World War II (1939-1945). Shortly after that, the
Binary Automatic Computer (BINAC) was introduced with a storage
device that appeared to be a large tape recorder. A more ad-

vanced machine, the Universal Automatic Computer (UNIVAC),
used metal tape instead of plastic (plastic was easily stretched or
even broken). Unfortunately, metal tape was considerably heavier,
and its edges were razor-sharp and thus dangerous. Improvements
in plastic tape eventually produced sturdy media, and magnetic
tape became (and remains) a practical medium for storage of computer
data.
Still later designs combined Booth’s spinning paper disks with
magnetic technology to produce rapidly rotating “drums.” Whereas
a tape might have to be fast-forwarded nearly to its end to locate a
specific piece of data, a drum rotating at speeds up to 12,500 revolutions
per minute (rpm) could retrieve data very quickly and
could store more than 1 million bits (or approximately 125 kilobytes)
of data.
In May, 1955, these drums evolved, under the direction of Reynold
B. Johnson, into IBM’s hard disk unit. The hard disk unit consisted
of fifty platters, each 2 feet in diameter, rotating at 1,200 rpm. Both
sides of the disk could be used to store information. When the operator
wished to access the disk, at his or her command a read/write
head was moved to the right disk and to the side of the disk that
held the desired data. The operator could then read data from or record
data onto the disk. To speed things even more, the next version
of the device, similar in design, employed one hundred read/write
heads—one for each of its fifty double-sided disks. The only remaining
disadvantage was its size, which earned IBM’s first commercial
unit the nickname “jukebox.”
The First Floppy
Floppy disk / 331
The floppy disk drive developed directly from hard disk technology.
It did not take shape until the late 1960’s under the direction of
Alan Shugart (it was announced by IBM as a ready product in 1970).
First created to help restart the operating systems of mainframe
computers that had gone dead, the floppy seemed in some ways to
be a step back, for it operated more slowly than a hard disk drive
and did not store as much data. Initially, it consisted of a single thin
plastic disk eight inches in diameter and was developed without the
protective envelope in which it is now universally encased. The ad-

332 / Floppy disk
dition of that jacket gave the floppy its single greatest advantage
over the hard disk: portability with reliability.
Another advantage soon became apparent: The floppy is resilient
to damage. In a hard disk drive, the read/write heads must
hover thousandths of a centimeter over the disk surface in order to
attain maximum performance. Should even a small particle of dust
get in the way, or should the drive unit be bumped too hard, the
head may “crash” into the surface of the disk and ruin its magnetic
coating; the result is a permanent loss of data. Because the floppy
operates with the read-write head in contact with the flexible plastic
disk surface, individual particles of dust or other contaminants are
not nearly as likely to cause disaster.
As a result of its advantages, the floppy disk was the logical
choice for mass storage in personal computers (PCs), which were
developed a few years after the floppy disk’s introduction. The
floppy is still an important storage device even though hard disk
drives for PCs have become less expensive. Moreover, manufacturers
continually are developing new floppy formats and new floppy
disks that can hold more data.
Three-and-one-half-inch disks improved on the design of earlier floppies by protecting their
magnetic media within hard plastic shells and using sliding metal flanges to protect the surfaces
on which recording heads make contact. (PhotoDisc)

Consequences
Floppy disk / 333
Personal computing would have developed very differently were
it not for the availability of inexpensive floppy disk drives. When
IBM introduced its PC in 1981, the machine provided as standard
equipment a connection for a cassette tape recorder as a storage device;
a floppy disk was only an option (though an option few did not
take). The awkwardness of tape drives—their slow speed and sequential
nature of storing data—presented clear obstacles to the acceptance
of the personal computer as a basic information tool. By
contrast, the floppy drive gives computer users relatively fast storage
at low cost.
Floppy disks provided more than merely economical data storage.
Since they are built to be removable (unlike hard drives), they
represented a basic means of transferring data between machines.
Indeed, prior to the popularization of local area networks (LANs),
the floppy was known as a “sneaker” network: One merely carried
the disk by foot to another computer.
Floppy disks were long the primary means of distributing new
software to users. Even the very flexible floppy showed itself to be
quite resilient to the wear and tear of postal delivery. Later, the 3.5inch
disk improved upon the design of the original 8-inch and 5.25inch
floppies by protecting the disk medium within a hard plastic
shell and by using a sliding metal door to protect the area where the
read/write heads contact the disk.
By the late 1990’s, floppy disks were giving way to new datastorage
media, particularly CD-ROMs—durable laser-encoded disks
that hold more than 700 megabytes of data. As the price of blank
CDs dropped dramatically, floppy disks tended to be used mainly
for short-term storage of small amounts of data. Floppy disks were
also being used less and less for data distribution and transfer, as
computer users turned increasingly to sending files via e-mail on
the Internet, and software providers made their products available
for downloading on Web sites.
See also Bubble memory; Compact disc; Computer chips; Hard
disk; Optical disk; Personal computer.

334 / Floppy disk
Further Reading
Brandel, Mary. “IBM Fashions the Floppy.” Computerworld 33, no. 23
(June 7, 1999).
Chposky, James, and Ted Leonsis. Blue Magic: The People, Power, and
Politics Behind the IBM Personal Computer. New York: Facts on File,
1988.
Freiberger, Paul, and Michael Swaine. Fire in the Valley: The Making of
the Personal Computer. New York: McGraw-Hill, 2000.
Grossman. Wendy. Remembering the Future: Interviews from Personal
Computer World. New York: Springer, 1997.

Fluorescent lighting
Fluorescent lighting
The invention: A form of electrical lighting that uses a glass tube
coated with phosphor that gives off a cool bluish light and emits
ultraviolet radiation.
The people behind the invention:
Vincenzo Cascariolo (1571-1624), an Italian alchemist and
shoemaker
Heinrich Geissler (1814-1879), a German glassblower
Peter Cooper Hewitt (1861-1921), an American electrical
engineer
Celebrating the “Twelve Greatest Inventors”
335
On the night of November 23, 1936, more than one thousand industrialists,
patent attorneys, and scientists assembled in the main
ballroom of the Mayflower Hotel in Washington, D.C., to celebrate
the one hundredth anniversary of the U.S. Patent Office. A transport
liner over the city radioed the names chosen by the Patent Office as
America’s “Twelve Greatest Inventors,” and, as the distinguished
group strained to hear those names, “the room was flooded for a
moment by the most brilliant light yet used to illuminate a space
that size.”
Thus did The New York Times summarize the commercial introduction
of the fluorescent lamp. The twelve inventors present were
Thomas Alva Edison, Robert Fulton, Charles Goodyear, Charles
Hall, Elias Howe, Cyrus Hall McCormick, Ottmar Mergenthaler,
Samuel F. B. Morse, George Westinghouse, Wilbur Wright, and Eli
Whitney. There was, however, no name to bear the honor for inventing
fluorescent lighting. That honor is shared by many who participated
in a very long series of discoveries.
The fluorescent lamp operates as a low-pressure, electric discharge
inside a glass tube that contains a droplet of mercury and a
gas, commonly argon. The inside of the glass tube is coated with
fine particles of phosphor. When electricity is applied to the gas, the
mercury gives off a bluish light and emits ultraviolet radiation.

336 / Fluorescent lighting
When bathed in the strong ultraviolet radiation emitted by the mercury,
the phosphor fluoresces (emits light).
The setting for the introduction of the fluorescent lamp began at
the beginning of the 1600’s, when Vincenzo Cascariolo, an Italian
shoemaker and alchemist, discovered a substance that gave off a
bluish glow in the dark after exposure to strong sunlight. The fluorescent
substance was apparently barium sulfide and was so unusual
for that time and so valuable that its formulation was kept secret
for a long time. Gradually, however, scholars became aware of
the preparation secrets of the substance and studied it and other luminescent
materials.
Further studies in fluorescent lighting were made by the German
physicist Johann Wilhelm Ritter. He observed the luminescence of
phosphors that were exposed to various “exciting” lights. In 1801,
he noted that some phosphors shone brightly when illuminated by
light that the eye could not see (ultraviolet light). Ritter thus discovered
the ultraviolet region of the light spectrum. The use of phosphors
to transform ultraviolet light into visible light was an important
step in the continuing development of the fluorescent lamp.
Further studies in fluorescent lighting were made by the German
physicist Johann Wilhelm Ritter. He observed the luminescence of
phosphors that were exposed to various “exciting” lights. In 1801,
he noted that some phosphors shone brightly when illuminated by
light that the eye could not see (ultraviolet light). Ritter thus discovered
the ultraviolet region of the light spectrum. The use of phosphors
to transform ultraviolet light into visible light was an important
step in the continuing development of the fluorescent lamp.
The British mathematician and physicist Sir George Gabriel Stokes
studied the phenomenon as well. It was he who, in 1852, termed the
afterglow “fluorescence.”
Geissler Tubes
While these advances were being made, other workers were trying
to produce a practical form of electric light. In 1706, the English
physicist Francis Hauksbee devised an electrostatic generator, which
is used to accelerate charged particles to very high levels of electrical
energy. He then connected the device to a glass “jar,” used a vac-

uum pump to evacuate the jar to a low pressure, and tested his
generator. In so doing, Hauksbee obtained the first human-made
electrical glow discharge by “capturing lightning” in a jar.
In 1854, Heinrich Geissler, a glassblower and apparatus maker,
opened his shop in Bonn, Germany, to make scientific instruments;
in 1855, he produced a vacuum pump that used liquid mercury as
an evacuation fluid. That same year, Geissler made the first gaseous
conduction lamps while working in collaboration with the German
scientist Julius Plücker. Plücker referred to these lamps as “Geissler
tubes.” Geissler was able to create red light with neon gas filling a
lamp and light of nearly all colors by using certain types of gas
within each of the lamps. Thus, both the neon sign business and the
science of spectroscopy were born.
Geissler tubes were studied extensively by a variety of workers.
At the beginning of the twentieth century, the practical American
engineer Peter Cooper Hewitt put these studies to use by marketing
the first low-pressure mercury vapor lamps. The lamps were quite
successful, although they required high voltage for operation, emitted
an eerie blue-green, and shone dimly by comparison with their
eventual successor, the fluorescent lamp. At about the same time,
systematic studies of phosphors had finally begun.
By the 1920’s, a number of investigators had discovered that the
low-pressure mercury vapor discharge marketed by Hewitt was an
extremely efficient method for producing ultraviolet light, if the
mercury and rare gas pressures were properly adjusted. With a
phosphor to convert the ultraviolet light back to visible light, the
Hewitt lamp made an excellent light source.
Impact
Fluorescent lighting / 337
The introduction of fluorescent lighting in 1936 presented the
public with a completely new form of lighting that had enormous
advantages of high efficiency, long life, and relatively low cost.
By 1938, production of fluorescent lamps was well under way. By
April, 1938, four sizes of fluorescent lamps in various colors had
been offered to the public and more than two hundred thousand
lamps had been sold.
During 1939 and 1940, two great expositions—the New York

338 / Fluorescent lighting
World’s Fair and the San Francisco International Exposition—
helped popularize fluorescent lighting. Thousands of tubular fluorescent
lamps formed a great spiral in the “motor display salon,”
the car showroom of the General Motors exhibit at the New York
World’s Fair. Fluorescent lamps lit the Polish Restaurant and hung
in vertical clusters on the flagpoles along the Avenue of the Flags at
the fair, while two-meter-long, upright fluorescent tubes illuminated
buildings at the San Francisco International Exposition.
When the United States entered World War II (1939-1945), the
demand for efficient factory lighting soared. In 1941, more than
twenty-one million fluorescent lamps were sold. Technical advances
continued to improve the fluorescent lamp. By the 1990’s,
this type of lamp supplied most of the world’s artificial lighting.
See also Electric clock; Electric refrigerator; Microwave cooking;
Television; Tungsten filament; Vacuum cleaner; Washing machine.
Further Reading
Bowers, B. “New Lamps for Old: The Story of Electric Lighting.” IEE
Review 41, no. 6 (November 16, 1995).
Dake, Henry Carl, and Jack De Ment. Fluorescent Light and Its Applications,
Including Location and Properties of Fluorescent Materials.
Brooklyn, N.Y.: Chemical Publishing, 1941.
“EPA Sees the Light on Fluorescent Bulbs.” Environmental Health
Perspectives 107, no. 12 (December, 1999).
Harris, J. B. “Electric Lamps, Past and Present.” Engineering Science
and Education Journal 2, no. 4 (August, 1993).
“How Fluorescent Lighting Became Smaller.” Consulting-Specifying
Engineer 23, no. 2 (February, 1998).

FM radio
FM radio
The invention: A method of broadcasting radio signals by modulating
the frequency, rather than the amplitude, of radio waves,
FM radio greatly improved the quality of sound transmission.
The people behind the invention:
Edwin H. Armstrong (1890-1954), the inventor of FM radio
broadcasting
David Sarnoff (1891-1971), the founder of RCA
An Entirely New System
339
Because early radio broadcasts used amplitude modulation (AM)
to transmit their sounds, they were subject to a sizable amount of interference
and static. Since good AM reception relies on the amount
of energy transmitted, energy sources in the atmosphere between
the station and the receiver can distort or weaken the original signal.
This is particularly irritating for the transmission of music.
Edwin H. Armstrong provided a solution to this technological
constraint. A graduate of Columbia University, Armstrong made a
significant contribution to the development of radio with his basic
inventions for circuits for AM receivers. (Indeed, the monies Armstrong
received from his earlier inventions financed the development
of the frequency modulation, or FM, system.) Armstrong was
one among many contributors to AM radio. For FM broadcasting,
however, Armstrong must be ranked as the most important inventor.
During the 1920’s, Armstrong established his own research laboratory
in Alpine, New Jersey, across the Hudson River from New
York City. With a small staff of dedicated assistants, he carried out
research on radio circuitry and systems for nearly three decades. At
that time, Armstrong also began to teach electrical engineering at
Columbia University.
From 1928 to 1933, Armstrong worked diligently at his private
laboratory at Columbia University to construct a working model of
an FM radio broadcasting system. With the primitive limitations
then imposed on the state of vacuum tube technology, a number of

340 / FM radio
Armstrong’s experimental circuits required as many as one hundred
tubes. Between July, 1930, and January, 1933, Armstrong filed
four basic FM patent applications. All were granted simultaneously
on December 26, 1933.
Armstrong sought to perfect FM radio broadcasting, not to offer
radio listeners better musical reception but to create an entirely
new radio broadcasting system. On November 5, 1935, Armstrong
made his first public demonstration of FM broadcasting in New
York City to an audience of radio engineers. An amateur station
based in suburban Yonkers, New York, transmitted these first signals.
The scientific world began to consider the advantages and
disadvantages of Armstrong’s system; other laboratories began to
craft their own FM systems.
Corporate Conniving
Because Armstrong had no desire to become a manufacturer or
broadcaster, he approached David Sarnoff, head of the Radio Corporation
of America (RCA). As the owner of the top manufacturer
of radio sets and the top radio broadcasting network, Sarnoff was
interested in all advances of radio technology. Armstrong first demonstrated
FM radio broadcasting for Sarnoff in December, 1933.
This was followed by visits from RCA engineers, who were sufficiently
impressed to recommend to Sarnoff that the company conduct
field tests of the Armstrong system.
In 1934, Armstrong, with the cooperation of RCA, set up a test
transmitter at the top of the Empire State Building, sharing facilities
with the experimental RCA television transmitter. From 1934 through
1935, tests were conducted using the Empire State facility, to mixed
reactions of RCA’s best engineers. AM radio broadcasting already
had a performance record of nearly two decades. The engineers
wondered if this new technology could replace something that had
worked so well.
This less-than-enthusiastic evaluation fueled the skepticism of
RCA lawyers and salespeople. RCA had too much invested in the
AM system, both as a leading manufacturer and as the dominant
owner of the major radio network of the time, the National Broadcasting
Company (NBC). Sarnoff was in no rush to adopt FM. To

change systems would risk the millions of dollars RCA was making
as America emerged from the Great Depression.
In 1935, Sarnoff advised Armstrong that RCA would cease any
further research and development activity in FM radio broadcasting.
(Still, engineers at RCA laboratories continued to work on FM
to protect the corporate patent position.) Sarnoff declared to the
press that his company would push the frontiers of broadcasting by
concentrating on research and development of radio with pictures,
that is, television. As a tangible sign, Sarnoff ordered that Armstrong’s
FM radio broadcasting tower be removed from the top of
the Empire State Building.
Armstrong was outraged. By the mid-1930’s, the development of
FM radio broadcasting had become a mission for Armstrong. For
the remainder of his life, Armstrong devoted his considerable talents
to the promotion of FM radio broadcasting.
Impact
FM radio / 341
After the break with Sarnoff, Armstrong proceeded with plans to
develop his own FM operation. Allied with two of RCA’s biggest
manufacturing competitors, Zenith and General Electric, Armstrong
pressed ahead. In June of 1936, at a Federal Communications Commission
(FCC) hearing, Armstrong proclaimed that FM broadcasting
was the only static-free, noise-free, and uniform system—both
day and night—available. He argued, correctly, that AM radio broadcasting
had none of these qualities.
During World War II (1939-1945), Armstrong gave the military
permission to use FM with no compensation. That patriotic gesture
cost Armstrong millions of dollars when the military soon became
all FM. It did, however, expand interest in FM radio broadcasting.
World War II had provided a field test of equipment and use.
By the 1970’s, FM radio broadcasting had grown tremendously.
By 1972, one in three radio listeners tuned into an FM station some
time during the day. Advertisers began to use FM radio stations to
reach the young and affluent audiences that were turning to FM stations
in greater numbers.
By the late 1970’s, FM radio stations were outnumbering AM stations.
By 1980, nearly half of radio listeners tuned into FM stations

342 / FM radio
on a regular basis. A decade later, FM radio listening accounted for
more than two-thirds of audience time. Armstrong’s predictions
that listeners would prefer the clear, static-free sounds offered by
FM radio broadcasting had come to pass by the mid-1980’s, nearly
fifty years after Armstrong had commenced his struggle to make
FM radio broadcasting a part of commercial radio.
See also Community antenna television; Communications satellite;
Dolby noise reduction; Fiber-optics; Radio; Radio crystal sets;
Television; Transistor radio.
Further Reading
Lewis, Tom. Empire of the Air: The Men Who Made Radio. New York:
HarperPerennial, 1993.
Sobel, Robert. RCA. New York: Stein and Day, 1986.
Streissguth, Thomas. Communications: Sending the Message. Minneapolis,
Minn.: Oliver Press, 1997.

Food freezing
Food freezing
The invention: It was long known that low temperatures helped to
protect food against spoiling; the invention that made frozen
food practical was a method of freezing items quickly. Clarence
Birdseye’s quick-freezing technique made possible a revolution
in food preparation, storage, and distribution.
The people behind the invention:
Clarence Birdseye (1886-1956), a scientist and inventor
Donald K. Tressler (1894-1981), a researcher at Cornell
University
Amanda Theodosia Jones (1835-1914), a food-preservation
pioneer
Feeding the Family
343
In 1917, Clarence Birdseye developed a means of quick-freezing
meat, fish, vegetables, and fruit without substantially changing
their original taste. His system of freezing was called by Fortune
magazine “one of the most exciting and revolutionary ideas in the
history of food.” Birdseye went on to refine and perfect his method
and to promote the frozen foods industry until it became a commercial
success nationwide.
It was during a trip to Labrador, where he worked as a fur trader,
that Birdseye was inspired by this idea. Birdseye’s new wife and
five-week-old baby had accompanied him there. In order to keep
his family well fed, he placed barrels of fresh cabbages in salt water
and then exposed the vegetables to freezing winds. Successful at
preserving vegetables, he went on to freeze a winter’s supply of
ducks, caribou, and rabbit meat.
In the following years, Birdseye experimented with many freezing
techniques. His equipment was crude: an electric fan, ice, and salt
water. His earliest experiments were on fish and rabbits, which he
froze and packed in old candy boxes. By 1924, he had borrowed
money against his life insurance and was lucky enough to find three
partners willing to invest in his new General Seafoods Company

344 / Food freezing
(later renamed General Foods), located in Gloucester, Massachusetts.
Although it was Birdseye’s genius that put the principles of
quick-freezing to work, he did not actually invent quick-freezing.
The scientific principles involved had been known for some time.
As early as 1842, a patent for freezing fish had been issued in England.
Nevertheless, the commercial exploitation of the freezing
process could not have happened until the end of the 1800’s, when
mechanical refrigeration was invented. Even then, Birdseye had to
overcome major obstacles.
Finding a Niche
By the 1920’s, there still were few mechanical refrigerators in
American homes. It would take years before adequate facilities for
food freezing and retail distribution would be established across the
United States. By the late 1930’s, frozen foods had, indeed, found its
role in commerce but still could not compete with canned or fresh
foods. Birdseye had to work tirelessly to promote the industry, writing
and delivering numerous lectures and articles to advance its
popularity. His efforts were helped by scientific research conducted
at Cornell University by Donald K. Tressler and by C. R. Fellers of
what was then Massachusetts State College. Also, during World
War II (1939-1945), more Americans began to accept the idea: Rationing,
combined with a shortage of canned foods, contributed to
the demand for frozen foods. The armed forces made large purchases
of these items as well.
General Foods was the first to use a system of extremely rapid
freezing of perishable foods in packages. Under the Birdseye system,
fresh foods, such as berries or lobster, were packaged snugly in convenient
square containers. Then, the packages were pressed between
refrigerated metal plates under pressure at 50 degrees below zero.
Two types of freezing machines were used. The “double belt” freezer
consisted of two metal belts that moved through a 15-meter freezing
tunnel, while a special salt solution was sprayed on the surfaces of
the belts. This double-belt freezer was used only in permanent installations
and was soon replaced by the “multiplate” freezer, which was
portable and required only 11.5 square meters of floor space compared
to the double belt’s 152 square meters.

Amanda Theodosia Jones
Food freezing / 345
Amanda Theodosia Jones (1835-1914) was close to her brother.
When he suddenly died while they were at school and she was
left to contact relatives and make the necessary arrangements
for his remains, she was devastated. She had a nervous breakdown
at seventeen and could not believe he was entirely gone.
She was sure that he remained an active presence in her life, and
she became a spiritualist and medium so that they could talk
during séances.
Jones always claimed she did not come up with the idea for
the vacuum packing method for preserving food, an important
technique before freezing foods became practicable. It was her
brother who gave it to her. She did the actual experimental
work herself, however, and with the aid of Leroy C. Cooley got
the first of their seven patents for food processing. In 1873 she
launched The Women’s Canning and Preserving Company, and
it was more than just a company. It was a mission. All the officers,
stockholders, and employees were women. “This is a
woman’s industry,” she insisted, and ran the company so that it
was a training school for working women.
In the 1880’s, the spirit of invention moved Jones again. Concerned
about the high rate of accidents among oil drillers, she
examined the problem. Simply add a safety valve to pipes to
control the release of the crude oil, she told drillers in Pennsylvania.
The idea had not occurred to them, but they tried it, and
it so improved safety that Jones won wide praise.
The multiplate freezer also made it possible to apply the technique
of quick-freezing to seasonal crops. People were able to transport
these freezers easily from one harvesting field to another,
where they were used to freeze crops such as peas fresh off the vine.
The handy multiplate freezer consisted of an insulated cabinet
equipped with refrigerated metal plates. Stacked one above the
other, these plates were capable of being opened and closed to receive
food products and to compress them with evenly distributed
pressure. Each aluminum plate had internal passages through which
ammonia flowed and expanded at a temperature of −3.8 degrees
Celsius, thus causing the foods to freeze.
A major benefit of the new frozen foods was that their taste and

346 / Food freezing
vitamin content were not lost. Ordinarily, when food is frozen
slowly, ice crystals form, which slowly rupture food cells, thus altering
the taste of the food. With quick-freezing, however, the food
looks, tastes, and smells like fresh food. Quick-freezing also cuts
down on bacteria.
Impact
During the months between one food harvest and the next, humankind
requires trillions of pounds of food to survive. In many
parts of the world, an adequate supply of food is available; elsewhere,
much food goes to waste and many go hungry. Methods of
food preservation such as those developed by Birdseye have done
much to help those who cannot obtain proper fresh foods. Preserving
perishable foods also means that they will be available in
greater quantity and variety all year-round. In all parts of the world,
both tropical and arctic delicacies can be eaten in any season of the
year.
With the rise in popularity of frozen “fast” foods, nutritionists
began to study their effect on the human body. Research has shown
that fresh is the most beneficial. In an industrial nation with many
people, the distribution of fresh commodities is, however, difficult.
It may be many decades before scientists know the long-term effects
on generations raised primarily on frozen foods.
See also Electric refrigerator; Freeze-drying; Microwave cooking;
Polystyrene; Refrigerant gas; Tupperware.
Further Reading
Altman, Linda Jacobs. Women Inventors. New York: Facts on File,
1997.
Tressler, Donald K. The Memoirs of Donald K. Tressler. Westport,
Conn.: Avi Publishing, 1976.
_____, and Clifford F. Evers. The Freezing Preservation of Foods. New
York: Avi Publishing, 1943.

FORTRAN programming
language
FORTRAN programming language
The invention: The first major computer programming language,
FORTRAN supported programming in a mathematical language
that was natural to scientists and engineers and achieved unsurpassed
success in scientific computation.
The people behind the invention:
John Backus (1924- ), an American software engineer and
manager
John W. Mauchly (1907-1980), an American physicist and
engineer
Herman Heine Goldstine (1913- ), a mathematician and
computer scientist
John von Neumann (1903-1957), a Hungarian American
mathematician and physicist
Talking to Machines
347
Formula Translation, or FORTRAN—the first widely accepted
high-level computer language—was completed by John Backus
and his coworkers at the International Business Machines (IBM)
Corporation in April, 1957. Designed to support programming
in a mathematical language that was natural to scientists and engineers,
FORTRAN achieved unsurpassed success in scientific
computation.
Computer languages are means of specifying the instructions
that a computer should execute and the order of those instructions.
Computer languages can be divided into categories of progressively
higher degrees of abstraction. At the lowest level is binary
code, or machine code: Binary digits, or “bits,” specify in
complete detail every instruction that the machine will execute.
This was the only language available in the early days of computers,
when such machines as the ENIAC (Electronic Numerical Integrator
and Calculator) required hand-operated switches and
plugboard connections. All higher levels of language are imple-

348 / FORTRAN programming language
mented by having a program translate instructions written in the
higher language into binary machine language (also called “object
code”). High-level languages (also called “programming languages”)
are largely or entirely independent of the underlying
machine structure. FORTRAN was the first language of this type
to win widespread acceptance.
The emergence of machine-independent programming languages
was a gradual process that spanned the first decade of electronic
computation. One of the earliest developments was the invention of
“flowcharts,” or “flow diagrams,” by Herman Heine Goldstine and
John von Neumann in 1947. Flowcharting became the most influential
software methodology during the first twenty years of
computing.
Short Code was the first language to be implemented that contained
some high-level features, such as the ability to use mathematical
equations. The idea came from John W. Mauchly, and it was
implemented on the BINAC (Binary Automatic Computer) in 1949
with an “interpreter”; later, it was carried over to the UNIVAC (Universal
Automatic Computer) I. Interpreters are programs that do
not translate commands into a series of object-code instructions; instead,
they directly execute (interpret) those commands. Every time
the interpreter encounters a command, that command must be interpreted
again. “Compilers,” however, convert the entire command
into object code before it is executed.
Much early effort went into creating ways to handle commonly
encountered problems—particularly scientific mathematical
calculations. A number of interpretive languages arose to
support these features. As long as such complex operations had
to be performed by software (computer programs), however, scientific
computation would be relatively slow. Therefore, Backus
lobbied successfully for a direct hardware implementation of these
operations on IBM’s new scientific computer, the 704. Backus then
started the Programming Research Group at IBM in order to develop
a compiler that would allow programs to be written in a
mathematically oriented language rather than a machine-oriented
language. In November of 1954, the group defined an initial version
of FORTRAN.

A More Accessible Language
Before FORTRAN was developed, a computer had to perform a
whole series of tasks to make certain types of mathematical calculations.
FORTRAN made it possible for the same calculations to be
performed much more easily. In general, FORTRAN supported constructs
with which scientists were already acquainted, such as functions
and multidimensional arrays. In defining a powerful notation
that was accessible to scientists and engineers, FORTRAN opened
up programming to a much wider community.
Backus’s success in getting the IBM 704’s hardware to support
scientific computation directly, however, posed a major challenge:
Because such computation would be much faster, the object code
produced by FORTRAN would also have to be much faster. The
lower-level compilers preceding FORTRAN produced programs
that were usually five to ten times slower than their hand-coded
counterparts; therefore, efficiency became the primary design objective
for Backus. The highly publicized claims for FORTRAN met
with widespread skepticism among programmers. Much of the
team’s efforts, therefore, went into discovering ways to produce the
most efficient object code.
The efficiency of the compiler produced by Backus, combined
with its clarity and ease of use, guaranteed the system’s success. By
1959, many IBM 704 users programmed exclusively in FORTRAN.
By 1963, virtually every computer manufacturer either had delivered
or had promised a version of FORTRAN.
Incompatibilities among manufacturers were minimized by the
popularity of IBM’s version of FORTRAN; every company wanted
to be able to support IBM programs on its own equipment. Nevertheless,
there was sufficient interest in obtaining a standard for
FORTRAN that the American National Standards Institute adopted
a formal standard for it in 1966. A revised standard was adopted in
1978, yielding FORTRAN 77.
Consequences
FORTRAN programming language / 349
In demonstrating the feasibility of efficient high-level languages,
FORTRAN inaugurated a period of great proliferation of program-

350 / FORTRAN programming language
ming languages. Most of these languages attempted to provide similar
or better high-level programming constructs oriented toward a
different, nonscientific programming environment. COBOL, for example,
stands for “Common Business Oriented Language.”
FORTRAN, while remaining the dominant language for scientific
programming, has not found general acceptance among nonscientists.
An IBM project established in 1963 to extend FORTRAN
found the task too unwieldy and instead ended up producing an entirely
different language, PL/I, which was delivered in 1966. In the
beginning, Backus and his coworkers believed that their revolutionary
language would virtually eliminate the burdens of coding and
debugging. Instead, FORTRAN launched software as a field of
study and an industry in its own right.
In addition to stimulating the introduction of new languages,
FORTRAN encouraged the development of operating systems. Programming
languages had already grown into simple operating systems
called “monitors.” Operating systems since then have been
greatly improved so that they support, for example, simultaneously
active programs (multiprogramming) and the networking (combining)
of multiple computers.
See also BASIC programming language; COBOL computer language;
SAINT.
Further Reading
Goff, Leslie. “Born of Frustration.” Computerworld 33, no. 6 (February
8, 1999).
Moreau, René. The Computer Comes of Age: The People, the Hardware,
and the Software. Cambridge, Mass.: MIT Press, 1984.
Slater, Robert. Portraits in Silicon. Cambridge, Mass.: MIT Press,
1987.
Stern, Nancy B. From ENIAC to UNIVAC: An Appraisal of the Eckert-
Mauchly Computers. Bedford, Mass.: Digital Press., 1981.

Freeze-drying
Freeze-drying
The invention: Method for preserving foods and other organic
matter by freezing them and using a vacuum to remove their
water content without damaging their solid matter.
The people behind the invention:
Earl W. Flosdorf (1904- ), an American physician
Ronald I. N. Greaves (1908- ), an English pathologist
Jacques Arsène d’Arsonval (1851-1940), a French physicist
Freeze-Drying for Preservation
351
Drying, or desiccation, is known to preserve biomaterials, including
foods. In freeze-drying, water is evaporated in a frozen
state in a vacuum, by means of sublimation (the process of changing
a solid to a vapor without first changing it to a liquid).
In 1811, John Leslie had first caused freezing by means of the
evaporation and sublimation of ice. In 1813, William Wollaston
demonstrated this process to the Royal Society of London. It does
not seem to have occurred to either Leslie or Wollaston to use sublimation
for drying. That distinction goes to Richard Altmann, a
German histologist, who dried pieces of frozen tissue in 1890.
Later, in 1903, Vansteenberghe freeze-dried the rabies virus. In
1906, Jacques Arsène d’Arsonval removed water at a low temperature
for distillation.
Since water removal is the essence of drying, d’Arsonval is often
credited with the discovery of freeze-drying, but the first clearly recorded
use of sublimation for preservation was by Leon Shackell in
1909. His work was widely recognized, and he freeze-dried a variety
of biological materials. The first patent for freeze-drying was issued
to Henri Tival, a French inventor, in 1927. In 1934, William
Elser received patents for a modern freeze-drying apparatus that
supplied heat for sublimation.
In 1933, Earl W. Flosdorf had freeze-dried human blood serum
and plasma for clinical use. The subsequent efforts of Flosdorf led to
commercial freeze-drying applications in the United States.

352 / Freeze-drying
Freeze-Drying of Foods
With the freeze-drying technique fairly well established for biological
products, it was a natural extension for Flosdorf to apply the
technique to the drying of foods. As early as 1935, Flosdorf experimented
with the freeze-drying of fruit juices and milk. An early British
patent was issued to Franklin Kidd, a British inventor, in 1941 for
the freeze-drying of foods. An experimental program on the freezedrying
of food was also initiated at the Low Temperature Research
Station at Cambridge University in England, but until World War II,
freeze-drying was only an occasionally used scientific tool.
It was the desiccation of blood plasma from the frozen state, performed
by the American Red Cross for the U.S. armed forces, that
provided the first spectacular, extensive use of freeze-drying. This
work demonstrated the vast potential of freeze-drying for commercial
applications. In 1949, Flosdorf published the first book on
freeze-drying, which laid the foundation for freeze-drying of foods
and remains one of the most important contributions to large-scale
operations in the field. In the book, Flosdorf described the freezedrying
of fruit juices, milk, meats, oysters, clams, fish fillets, coffee
and tea extracts, fruits, vegetables, and other products. Flosdorf also
devoted an entire chapter to describing the equipment used for both
batch and continuous processing, and he discussed cost analysis.
The holder of more than fifteen patents covering various aspects of
freeze-drying, Flosdorf dominated the move toward commercialization
in the United States.
Simultaneously, researchers in England were developing freezedrying
applications under the leadership of Ronald I. N. Greaves.
The food crisis during World War II had led to the recognition that
dried foods cut the costs of transporting, storing, and packaging
foods in times of emergency. Thus, in 1951, the British Ministry of
Food Research was established at Aberdeen, Scotland. Scientists at
Aberdeen developed a vacuum contact plate freeze-dryer that improved
product quality and reduced the time required for rehydration
(replacement of the water removed in the freeze-drying
process so that the food can be used).
In 1954, trials of initial freeze-drying, followed by the ordinary
process of vacuum drying, were carried out. The abundance of

membranes within plant and animal tissues was a major obstacle to
the movement of water vapor, thus limiting the drying rate. In 1956,
two Canadian scientists developed a new method of improving the
freeze-drying rate for steaks by impaling the steaks on spiked heater
plates. This idea was adapted in 1957 by interposing sheets of expanded
metal, instead of spikes, between the drying surfaces of the
frozen food and the heating platens. Because of the substantially
higher freeze-drying rates that it achieved, the process was called
“accelerated freeze-drying.”
In 1960, Greaves described an ingenious method of freeze-drying
liquids. It involved continuously scraping the dry layer during its
formation. This led to a continuous process for freeze-drying liquids.
During the remainder of the 1960’s, freeze-drying applications
proliferated with the advent of several techniques for controlling
and improving the effectiveness of the freeze-drying process.
Impact
Freeze-drying / 353
Flosdorf’s vision and ingenuity in applying freeze-drying to
foods has revolutionized food preservation. He was also responsible
for making a laboratory technique a tremendous commercial
success.
Freeze-drying is important because it stops the growth of microorganisms,
inhibits deleterious chemical reactions, and facilitates
distribution and storage. Freeze-dried foods are easily prepared for
consumption by adding water (rehydration). When freeze-dried
properly, most foods, either raw or cooked, can be rehydrated
quickly to yield products that are equal in quality to their frozen
counterparts. Freeze-dried products retain most of their nutritive
qualities and have a long storage life, even at room temperature.
Freeze-drying is not, however, without disadvantages. The major
disadvantage is the high cost of processing. Thus, to this day, the
great potential of freeze-drying has not been fully realized. The drying
of cell-free materials, such as coffee and tea extracts, has been extremely
successful, but the obstacles imposed by the cell membranes
in foods such as fruits, vegetables, and meats have limited
the application to expensive specialty items such as freeze-dried
soups and to foods for armies, campers, and astronauts. Future eco-

354 / Freeze-drying
nomic changes may create a situation in which the high cost of
freeze-drying is more than offset by the cost of transportation and
storage.
See also Electric refrigerator; Food freezing; Polystyrene; Tupperware.
Further Reading
Comello, Vic. “Improvements in Freeze Drying Expand Application
Base.” Research and Development 42, no. 5 (May, 2000).
Flosdorf, Earl William. Freeze-Drying: Drying by Sublimation. New
York: Reinhold, 1949.
Noves, Robert. Freeze Drying of Foods and Biologicals, 1968. Park
Ridge, N.J.: Noyes Development Corporation, 1968.

Fuel cell
Fuel cell
The invention: An electrochemical cell that directly converts energy
from reactions between oxidants and fuels, such as liquid
hydrogen, into electrical energy.
The people behind the invention:
Francis Thomas Bacon (1904-1992), an English engineer
Sir William Robert Grove (1811-1896), an English inventor
Georges Leclanché (1839-1882), a French engineer
Alessandro Volta (1745-1827), an Italian physicist
The Earth’s Resources
Because of the earth’s rapidly increasing population and the
dwindling of fossil fuels (natural gas, coal, and petroleum), there is
a need to design and develop new ways to obtain energy and to encourage
its intelligent use. The burning of fossil fuels to create energy
causes a slow buildup of carbon dioxide in the atmosphere,
creating pollution that poses many problems for all forms of life on
this planet. Chemical and electrical studies can be combined to create
electrochemical processes that yield clean energy.
Because of their very high rate of efficiency and their nonpolluting
nature, fuel cells may provide the solution to the problem of
finding sufficient energy sources for humans. The simple reaction of
hydrogen and oxygen to form water in such a cell can provide an
enormous amount of clean (nonpolluting) energy. Moreover, hydrogen
and oxygen are readily available.
Studies by Alessandro Volta, Georges Leclanché, and William
Grove preceded the work of Bacon in the development of the fuel
cell. Bacon became interested in the idea of a hydrogen-oxygen fuel
cell in about 1932. His original intent was to develop a fuel cell that
could be used in commercial applications.
The Fuel Cell Emerges
355
In 1800, the Italian physicist Alessandro Volta experimented
with solutions of chemicals and metals that were able to conduct

356 / Fuel cell
electricity. He found that two pieces of metal and such a solution
could be arranged in such a way as to produce an electric current.
His creation was the first electrochemical battery, a device that produced
energy from a chemical reaction. Studies in this area were
continued by various people, and in the late nineteenth century,
Georges Leclanché invented the dry cell battery, which is now commonly
used.
The work of William Grove followed that of Leclanché. His first
significant contribution was the Grove cell, an improved form of the
cells described above, which became very popular. Grove experimented
with various forms of batteries and eventually invented the
“gas battery,” which was actually the earliest fuel cell. It is worth
noting that his design incorporated separate test tubes of hydrogen
and oxygen, which he placed over strips of platinum.
After studying the design of Grove’s fuel cell, Bacon decided
that, for practical purposes, the use of platinum and other precious
metals should be avoided. By 1939, he had constructed a cell in
which nickel replaced the platinum used.
The theory behind the fuel cell can be described in the following
way. If a mixture of hydrogen and oxygen is ignited, energy is released
in the form of a violent explosion. In a fuel cell, however, the
reaction takes place in a controlled manner. Electrons lost by the hydrogen
gas flow out of the fuel cell and return to be taken up by the
oxygen in the cell. The electron flow provides electricity to any device
that is connected to the fuel cell, and the water that the fuel cell
produces can be purified and used for drinking.
Bacon’s studies were interrupted by World War II. After the war
was over, however, Bacon continued his work. Sir Eric Keightley
Rideal of Cambridge University in England supported Bacon’s
studies; later, others followed suit. In January, 1954, Bacon wrote an
article entitled “Research into the Properties of the Hydrogen/ Oxygen
Fuel Cell” for a British journal. He was surprised at the speed
with which news of the article spread throughout the scientific
world, particularly in the United States.
After a series of setbacks, Bacon demonstrated a forty-cell unit
that had increased power. This advance showed that the fuel cell
was not merely an interesting toy; it had the capacity to do useful
work. At this point, the General Electric Company (GE), an Ameri-

can corporation, sent a representative to England to offer employment
in the United States to senior members of Bacon’s staff. Three scientists
accepted the offer.
A high point in Bacon’s career was the announcement that the
American Pratt and Whitney Aircraft company had obtained an order
to build fuel cells for the Apollo project, which ultimately put
two men on the Moon in 1969. Toward the end of his career in 1978,
Bacon hoped that commercial applications for his fuel cells would
be found.
Impact
H 2
- +
Electrolyte
Porous
Electrodes
Anode Cathode
Parts of a basic fuel cell
Fuel cell / 357
Because they are lighter and more efficient than batteries, fuel
cells have proved to be useful in the space program. Beginning with
the Gemini 5 spacecraft, alkaline fuel cells (in which a water solution
of potassium hydroxide, a basic, or alkaline, chemical, is placed)
have been used for more than ten thousand hours in space. The fuel
cells used aboard the space shuttle deliver the same amount of power
as batteries weighing ten times as much. On a typical seven-day
mission, the shuttle’s fuel cells consume 680 kilograms (1,500 pounds)
of hydrogen and generate 719 liters (190 gallons) of water that can
be used for drinking.
Major technical and economic problems must be overcome in order
to design fuel cells for practical applications, but some important
advancements have been made. Afew test vehicles that use fuel
O 2

358 / Fuel cell
Francis Bacon
Born in Billericay, England, in 1904, Francis Thomas Bacon
completed secondary school at the prestigious Eton College
and then attended Trinity College, Cambridge University. In
1932 he started his long search for a practical fuel cell based
upon the oxygen-hydrogen (Hydrox) reaction with an alkaline
electrolyte and inexpensive nickel electrodes. In 1940 the British
Admiralty set him up in full-time experimental work at King’s
College, London, and then moved him to the Anti-Submarine
Experimental Establishment because the Royal Navy wanted
fuel cells for their submarines.
After World War II Cambridge University appointed him to
the faculty at the Department of Chemical Engineering, and he
worked intensively on his fuel cell research. In 1959 he proved
the worth of his work by producing a fuel cell capable of powering
a small truck. It was not until the 1990’s, however, that fuel
cells were taken seriously as the main power source for automobiles.
In 1998, for instance, Iceland enlisted the help of Daimler-
Chrysler, Shell Oil, and Norsk Hydro to convert all its transportation
vehicles, including its fishing boats, to fuel cell power,
part of its long-range plans for a completely “hydrogen economy.”
Meanwhile, Bacon had the satisfaction of seeing his invention
become a power source for American space vehicles
and stations. He died in 1992 in Cambridge.
cells as a source of power have been constructed. Fuel cells using
hydrogen as a fuel and oxygen to burn the fuel have been used in a
van built by General Motors Corporation. Thirty-two fuel cells are
installed below the floorboards, and tanks of liquid oxygen are carried
in the back of the van. A power plant built in New York City
contains stacks of hydrogen-oxygen fuel cells, which can be put on
line quickly in response to power needs. The Sanyo Electric Company
has developed an electric car that is partially powered by a
fuel cell.
These tremendous technical advances are the result of the singleminded
dedication of Francis Thomas Bacon, who struggled all of
his life with an experiment he was convinced would be successful.

See also Alkaline storage battery; Breeder reactor; Compressedair-accumulating
power plant; Fluorescent lighting; Geothermal
power; Heat pump; Photoelectric cell; Photovoltaic cell; Solar thermal
engine; Tidal power plant.
Further Reading
Fuel cell / 359
Eisenberg, Anne. “Fuel Cell May Be the Future ‘Battery.’” New York
Times (October 21, 1999).
Hoverstein, Paul. “Century-Old Invention Finding a Niche Today.
USA Today (June 3, 1994).
Kufahl, Pam. “Electric: Lighting Up the Twentieth Century.” Unity
Business 3, no. 7 (June, 2000).
Stobart, Richard. Fuel Cell Technology for Vehicles. Warrendale, Pa.:
Society of Automotive Engineers, 2001.

360
Gas-electric car
Gas-electric car
The invention: A hybrid automobile with both an internal combustion
engine and an electric motor.
The people behind the invention:
Victor Wouk (1919- ), an American engineer
Tom Elliott, executive vice president of American Honda Motor
Company
Hiroyuki Yoshino, president and chief executive officer of
Honda Motor Company
Fujio Cho, president of Toyota Motor Corporation
Announcing Hybrid Vehicles
At the 2000 North American International Auto Show in Detroit,
not only did the Honda Motor Company show off its new Insight
model, it also announced expanded use of its new technology. Hiroyuki
Yoshino, president and chief executive officer, said that Honda’s integrated
motor assist (IMA) system would be expanded to other massmarket
models. The system basically fits a small electric motor directly
on a one-liter, three-cylinder internal combustion engine. The two
share the workload of powering the car, but the gasoline engine does
not start up until it is needed. The electric motor is powered by a
nickel-metal hydride (Ni-MH) battery pack, with the IMA system automatically
recharging the energy pack during braking.
Tom Elliott, Honda’s executive vice-president, said the vehicle
was a continuation of the company’s philosophy of making the latest
environmental technology accessible to consumers. The $18,000
Insight was a two-seat sporty car that used many innovations to reduce
its weight and improve its performance.
Fujio Cho, president of Toyota, also spoke at the Detroit show,
where his company showed off its new $20,000 hybrid Prius. The Toyota
Prius relied more on the electric motor and had more energystorage
capacity than the Insight, but was a four-door, five-seat model.
The Toyota Hybrid System divided the power from its 1.5-liter gasoline
engine and directed it to drive the wheels and a generator. The

generator alternately powered the motor and recharged the batteries.
The electric motor was coupled with the gasoline engine to
power the wheels under normal driving. The gasoline engine supplied
average power needs, with the electric motor helping the
peaks; at low speeds, it was all electric. A variable transmission
seamlessly switched back and forth between the gasoline engine
and electric motor or applied both of them.
Variations on an Idea
Gas-electric car / 361
Automobiles generally use gasoline or diesel engines for driving,
electric motors that start the main motors, and a means of recharging
the batteries that power starter motors and other devices. In
solely electric cars, gasoline engines are eliminated entirely, and the
batteries that power the vehicles are recharged from stationary
sources. In hybrid cars, the relationship between gasoline engines
and electric motors is changed so that electric motors handle some
or all of the driving. This is at the expense of an increased number of
batteries or other energy-storage devices.
Possible in many combinations, “hybrids” couple the low-end
torque and regenerative braking potential of electric motors with
the range and efficient packaging of gasoline, natural gas, or even
hydrogen fuel power plants. The return is greater energy efficiency
and reduced pollution.
With sufficient energy-storage capacity, an electric motor can
actually propel a car from a standing start to a moving speed. In
hybrid vehicles, the gasoline engines—which are more energyefficient
at higher speeds, then kick in. However, the gasoline engines
in these vehicles are smaller, lighter, and more efficient than
ordinary gas engines. Designed for average—not peak—driving
conditions, they reduce air pollution and considerably improve
fuel economy.
Batteries in hybrid vehicles are recharged partly by the gas engines
and partly by regenerative braking; a third of the energy from
slowing the car is turned into electricity. What has finally made hybrids
feasible at reasonable cost are the new developments in computer
technology, allowing sophisticated controls to coordinate electrical
and mechanical power.

362 / Gas-electric car
Victor Wouk
H. Piper, an American engineer, filed the first patent for a
hybrid gas-electric powered car in 1905, and from then until
1915 they were popular, although not common, because they
could accelerate faster than plain gas-powered cars. Then the
gas-only models became as swift. Their hybrid cousins fells by
the wayside.
Interest in hybrids revived with the unheard-of gasoline
prices during the 1973 oil crisis. The champion of their comeback—the
father of the modern hybrid electric vehicle (HEV)—
was Victor Wouk. Born in 1919 in New York City, Wouk earned
a math and physics degree from Columbia University in 1939
and a doctorate in electrical engineering from the California Institute
of Technology in 1942. In 1946 he founded Beta Electric
Corporation, which he led until 1959, when he founded and
was president of another company, Electronic Energy Conversion
Corporation. After 1970, he became an independent consultant,
hoping to build an HEV that people would prefer to
gas-guzzlers.
With his partner, Charles Rosen, Wouk gutted the engine
compartment of a Buick Skylark and installed batteries designed
for police cars, a 20-watt direct-current electric motor,
and an RX-2 Mazda rotary engine. Only a test vehicle, it still got
better gas mileage (thirty miles per gallon) than the original
Skylark and met the requirements for emissions control set by
the Clean Air Act of 1970, unlike all American automobiles of
the era. Moreover, Wouk designed an HEV that would get fifty
miles per gallon and pollute one-eighth as much as gas-powered
automobiles. However, the oil crisis ended, gas prices went
down, and consumers and the government lost interest. Wouk
continued to publish, lecture, and design; still, it was not until
the 1990’s that high gas prices and concerns over pollution
made HEV’s attractive yet again.
Wouk holds twelve patents, mostly for speed and braking
controls in electric vehicles but also for air conditioning, high
voltage direct-current power sources, and life extenders for incandescent
lamps.

One way to describe hybrids is to separate them into two types:
parallel, in which either of the two power plants can propel the vehicle,
and series, in which the auxiliary power plant is used to
charge the battery, rather than propel the vehicle.
Honda’s Insight is a simplified parallel hybrid that uses a small
but efficient gasoline engine. The electric motor assists the engine,
providing extra power for acceleration or hill climbing, helps provide
regenerative braking, and starts the engine. However, it cannot
run the car by itself.
Toyota’s Prius is a parallel hybrid whose power train allows
some series features. Its engine runs only at an efficient speed and
load and is combined with a unique power splitting device. It allows
the car to operate like a parallel hybrid, motor alone, engine
alone, or both. It can act as a series hybrid with the engine charging
the batteries rather than powering the vehicle. It also provides a
continually variable transmission using a planetary gear set that allows
interaction between the engine, the motor, and the differential
which drives the wheels.
Impact
Gas-electric car / 363
In 2001 Honda and Toyota marketed gas-electric hybrids that offered
better than 60-mile-per-gallon fuel economy and met California’s
stringent standards for “super ultra-low emissions” vehicles.
Both comparnies achieved these standards without the inconvenience
of fully electric cars which could go only about a hundred
miles on a single battery charge and required such gimmicks as kerosene-powered
heaters. As a result, other manufacturers were beginning
to follow suit. Ford, for example, promised a hybrid sport
utility vehicle (SUV) by 2003. Other automakers, including General
Motors and DaimlerChrysler, also have announced development of
alternative fuel and low emission vehicles. An example is the ESX3
concept car using a 1.5-liter, direct injection diesel combined with a
electric motor and a lithium-ion battery
While American automakers were planning to offer some “full
hybrids”—cars capable of running on battery power alone at low
speeds—they were focusing more enthusiastically on electrically
assisted gasoline engines called “mild hybrids.” Full hybrids typi-

364 / Gas-electric car
cally increase gas mileage by up to 60 percent; mild hybrids by only
10 or 20 percent. The “mild hybrid” approach uses regenerative
braking with electrical systems of a much lower voltage and storage
capacity than for full hybrids, a much cheaper approach. But there
still is enough energy available to allow the gasoline engine to turn
off automatically when a vehicle stops and turn on instantly when
the accelerator is touched. Because the “mild hybrid” approach
adds only $1000 to $1500 to a vehicle’s price, it is likely to be used in
many models. Full hybrids cost much more, but achieve more benefits.
See also Airplane; Diesel locomotive; Hovercraft; Internal combustion
engine; Supersonic passenger plane; Turbojet.
Further Reading
Morton, Ian. “Honda Insight Hybrid Makes Heavy Use of Light
Metal.” Automotive News 74, no. 5853 (December 20, 1999).
Peters, Eric. “Hybrid Cars: The Hope, Hype, and Future.” Consumers’
Research Magazine 83, no. 6 (June, 2000).
Reynolds, Kim. “Burt Rutan Ponders the Hybrid Car.” Road and
Track 51, no. 11 (July, 2000).
Swoboda, Frank. “’Hybrid’ Cars Draw Waiting List of Buyers.”
Washington Post (May 3, 2001).
Yamaguchi, Jack. “Toyota Prius IC/Electric Hybrid Update.” Automotive
Engineering International 108, no. 12 (December, 2000).

Geiger counter
Geiger counter
The invention: the first electronic device able to detect and measure
radioactivity in atomic particles.
The people behind the invention:
Hans Geiger (1882-1945), a German physicist
Ernest Rutherford (1871-1937), a British physicist
Sir John Sealy Edward Townsend (1868-1957), an Irish physicist
Sir William Crookes (1832-1919), an English physicist
Wilhelm Conrad Röntgen (1845-1923), a German physicist
Antoine-Henri Becquerel (1852-1908), a French physicist
Discovering Natural Radiation
365
When radioactivity was discovered and first studied, the work
was done with rather simple devices. In the 1870’s, Sir William
Crookes learned how to create a very good vacuum in a glass tube.
He placed electrodes in each end of the tube and studied the passage
of electricity through the tube. This simple device became known as
the “Crookes tube.” In 1895, Wilhelm Conrad Röntgen was experimenting
with a Crookes tube. It was known that when electricity
went through a Crookes tube, one end of the glass tube might glow.
Certain mineral salts placed near the tube would also glow. In order
to observe carefully the glowing salts, Röntgen had darkened the
room and covered most of the Crookes tube with dark paper. Suddenly,
a flash of light caught his eye. It came from a mineral sample
placed some distance from the tube and shielded by the dark paper;
yet when the tube was switched off, the mineral sample went dark.
Experimenting further, Röntgen became convinced that some ray
from the Crookes tube had penetrated the mineral and caused it to
glow. Since light rays were blocked by the black paper, he called the
mystery ray an “X ray,” with “X” standing for unknown.
Antoine-Henri Becquerel heard of the discovery of X rays and, in
February, 1886, set out to discover if glowing minerals themselves
emitted X rays. Some minerals, called “phosphorescent,” begin to
glow when activated by sunlight. Becquerel’s experiment involved

366 / Geiger counter
wrapping photographic film in black paper and setting various
phosphorescent minerals on top and leaving them in the sun. He
soon learned that phosphorescent minerals containing uranium
would expose the film.
A series of cloudy days, however, brought a great surprise. Anxious
to continue his experiments, Becquerel decided to develop film
that had not been exposed to sunlight. He was astonished to discover
that the film was deeply exposed. Some emanations must be
coming from the uranium, he realized, and they had nothing to do
with sunlight. Thus, natural radioactivity was discovered by accident
with a simple piece of photographic film.
Rutherford and Geiger
Ernest Rutherford joined the world of international physics at
about the same time that radioactivity was discovered. Studying the
“Becquerel rays” emitted by uranium, Rutherford eventually distinguished
three different types of radiation, which he named “alpha,”
“beta,” and “gamma” after the first three letters of the Greek alphabet.
He showed that alpha particles, the least penetrating of the three, are
the nuclei of helium atoms (a group of two neutrons and a proton
tightly bound together). It was later shown that beta particles are electrons.
Gamma rays, which are far more penetrating than either alpha
or beta particles, were shown to be similar to X rays, but with higher
energies.
Rutherford became director of the associated research laboratory
at Manchester University in 1907. Hans Geiger became an assistant.
At this time, Rutherford was trying to prove that alpha particles
carry a double positive charge. The best way to do this was to measure
the electric charge that a stream of alpha particles would bring
to a target. By dividing that charge by the total number of alpha particles
that fell on the target, one could calculate the charge of a single
alpha particle. The problem lay in counting the particles and in
proving that every particle had been counted.
Basing their design upon work done by Sir John Sealy Edward
Townsend, a former colleague of Rutherford, Geiger and Rutherford
constructed an electronic counter. It consisted of a long brass
tube sealed at both ends from which most of the air had been

Hans Geiger
Geiger counter / 367
Atomic radiation was the first physical phenomenon that
humans discovered that they could not detect with any of their
five natural senses. Hans Geiger found a way to make radiation
observable.
Born into a family with an academic tradition in 1882, Geiger
became an academician himself. His father was a professor
of linguistics at the University of Erlangen, where Geiger completed
his own doctorate in physics in 1906. One of the world’s
centers for experimental physics at the time was England, and
there Geiger went in 1907. He became an assistant to Ernest
Rutherford at the University of Manchester and thereby began
the first of a series of successful collaborations during his career—all
devoted to detecting or explaining types of radiation.
Rutherford had distinguished three types of radiation. In
1908, he and Geiger built a device to sense the first alpha particles.
It gave them evidence for Rutherford’s conjecture that the
atom was structured like a miniature solar system. Geiger also
worked closely with Ernest Marsden, James Chadwick, and
Walter Bothe on aspects of radiation physics.
Geiger’s stay in England ended with the outbreak of World
War I in 1914. He returned to Germany and served as an artillery
officer. Immediately after the war he took up university
posts again, first in Berlin, then in Kiel, Tubingen, and back to
Berlin. With Walther Müller he perfected a compact version of
the radiation detector in 1925, the Geiger- Müller counter. It became
the standard radiation sensor for scientists thereafter, and,
during the rush to locate uranium deposits during the 1950’s,
for prospectors.
Geiger used it to prove the existence of the Compton effect,
which concerned the scattering of X rays, and his experiments
further proved beyond doubt that light can take the form of
quanta. He also discovered cosmic-ray showers with his detector.
Geiger remained in German during World War II, although
he vigorously opposed the Nazi party’s treatment of scientists.
He died in Potsdam in 1945, after losing his home and possessions
during the Allied occupation of Berlin.

368 / Geiger counter
pumped. A thin wire, insulated from the brass, was suspended
down the middle of the tube. This wire was connected to batteries
producing about thirteen hundred volts and to an electrometer, a
device that could measure the voltage of the wire. This voltage
could be increased until a spark jumped between the wire and the
tube. If the voltage was turned down a little, the tube was ready to
operate. An alpha particle entering the tube would ionize (knock
some electrons away from) at least a few atoms. These electrons
would be accelerated by the high voltage and, in turn, would ionize
more atoms, freeing more electrons. This process would continue
until an avalanche of electrons struck the central wire and the electrometer
registered the voltage change. Since the tube was nearly
ready to arc because of the high voltage, every alpha particle, even if
it had very little energy, would initiate a discharge. The most complex
of the early radiation detection devices—the forerunner of the
Geiger counter—had just been developed. The two physicists reported
their findings in February, 1908.
Impact
Their first measurements showed that one gram of radium
emitted 34 thousand million alpha particles per second. Soon, the
number was refined to 32.8 thousand million per second. Next,
Geiger and Rutherford measured the amount of charge emitted
by radium each second. Dividing this number by the previous
number gave them the charge on a single alpha particle. Just as
Rutherford had anticipated, the charge was double that of a hydrogen
ion (a proton). This proved to be the most accurate determination
of the fundamental charge until the American physicist
Robert Andrews Millikan conducted his classic oil-drop experiment
in 1911.
Another fundamental result came from a careful measurement of
the volume of helium emitted by radium each second. Using that
value, other properties of gases, and the number of helium nuclei
emitted each second, they were able to calculate Avogadro’s number
more directly and accurately than had previously been possible.
(Avogadro’s number enables one to calculate the number of atoms
in a given amount of material.)

The true Geiger counter evolved when Geiger replaced the central
wire of the tube with a needle whose point lay just inside a thin
entrance window. This counter was much more sensitive to alpha
and beta particles and also to gamma rays. By 1928, with the assistance
of Walther Müller, Geiger made his counter much more efficient,
responsive, durable, and portable. There are probably few radiation
facilities in the world that do not have at least one Geiger
counter or one of its compact modern relatives.
See also Carbon dating; Gyrocompass; Radar; Sonar; Richter
scale.
Further Reading
Geiger counter / 369
Campbell, John. Rutherford: Scientist Supreme. Christchurch, New
Zealand: AAS Publications, 1999.
Halacy, D. S. They Gave Their Names to Science. New York: Putnam,
1967.
Krebs, A. T. “Hans Geiger: Fiftieth Anniversary of the Publication of
His Doctoral Thesis, 23 July 1906.” Science 124 (1956).
Weir, Fred. “Muscovites Check Radishes for Radiation; a $50 Personal
Geiger Counter Gives Russians a Sense of Confidence at
the Market.” Christian Science Monitor (November 4, 1999).

370
Genetic “fingerprinting”
Genetic “fingerprinting”
The invention: A technique for using the unique characteristics of
each human being’s DNA to identify individuals, establish connections
among relatives, and identify criminals.
The people behind the invention:
Alec Jeffreys (1950- ), an English geneticist
Victoria Wilson (1950- ), an English geneticist
Swee Lay Thein (1951- ), a biochemical geneticist
Microscopic Fingerprints
In 1985, Alec Jeffreys, a geneticist at the University of Leicester in
England, developed a method of deoxyribonucleic acid (DNA)
analysis that provides a visual representation of the human genetic
structure. Jeffreys’s discovery had an immediate, revolutionary impact
on problems of human identification, especially the identification
of criminals. Whereas earlier techniques, such as conventional
blood typing, provide evidence that is merely exclusionary (indicating
only whether a suspect could or could not be the perpetrator of a
crime), DNA fingerprinting provides positive identification.
For example, under favorable conditions, the technique can establish
with virtual certainty whether a given individual is a murderer
or rapist. The applications are not limited to forensic science;
DNA fingerprinting can also establish definitive proof of parenthood
(paternity or maternity), and it is invaluable in providing
markers for mapping disease-causing genes on chromosomes. In
addition, the technique is utilized by animal geneticists to establish
paternity and to detect genetic relatedness between social groups.
DNA fingerprinting (also referred to as “genetic fingerprinting”)
is a sophisticated technique that must be executed carefully to produce
valid results. The technical difficulties arise partly from the
complex nature of DNA. DNA, the genetic material responsible for
heredity in all higher forms of life, is an enormously long, doublestranded
molecule composed of four different units called “bases.”
The bases on one strand of DNA pair with complementary bases on

the other strand. A human being contains twenty-three pairs of
chromosomes; one member of each chromosome pair is inherited
from the mother, the other from the father. The order, or sequence, of
bases forms the genetic message, which is called the “genome.” Scientists
did not know the sequence of bases in any sizable stretch of
DNA prior to the 1970’s because they lacked the molecular tools to
split DNA into fragments that could be analyzed. This situation
changed with the advent of biotechnology in the mid-1970’s.
The door to DNA analysis was opened with the discovery of bacterial
enzymes called “DNA restriction enzymes.” A restriction enzyme
binds to DNA whenever it finds a specific short sequence of
base pairs (analogous to a code word), and it splits the DNA at a defined
site within that sequence. A single enzyme finds millions of
cutting sites in human DNA, and the resulting fragments range in
size from tens of base pairs to hundreds or thousands. The fragments
are exposed to a radioactive DNA probe, which can bind to
specific complementary DNA sequences in the fragments. X-ray
film detects the radioactive pattern. The developed film, called an
“autoradiograph,” shows a pattern of DNA fragments, which is
similar to a bar code and can be compared with patterns from
known subjects.
The Presence of Minisatellites
Genetic “fingerprinting” / 371
The uniqueness of a DNA fingerprint depends on the fact that,
with the exception of identical twins, no two human beings have
identical DNA sequences. Of the three billion base pairs in human
DNA, many will differ from one person to another.
In 1985, Jeffreys and his coworkers, Victoria Wilson at the University
of Leicester and Swee Lay Thein at the John Radcliffe Hospital
in Oxford, discovered a way to produce a DNA fingerprint.
Jeffreys had found previously that human DNA contains many repeated
minisequences called “minisatellites.” Minisatellites consist
of sequences of base pairs repeated in tandem, and the number of
repeated units varies widely from one individual to another. Every
person, with the exception of identical twins, has a different number
of tandem repeats and, hence, different lengths of minisatellite
DNA. By using two labeled DNA probes to detect two different

372 / Genetic “fingerprinting”
minisatellite sequences, Jeffreys obtained a unique fragment band
pattern that was completely specific for an individual.
The power of the technique derives from the law of chance,
which indicates that the probability (chance) that two or more unrelated
events will occur simultaneously is calculated as the multiplication
product of the two separate probabilities. As Jeffreys discovered,
the likelihood of two unrelated people having completely
identical DNA fingerprints is extremely small—less than one in ten
trillion. Given the population of the world, it is clear that the technique
can distinguish any one person from everyone else. Jeffreys
called his band patterns “DNA fingerprints” because of their ability
to individualize. As he stated in his landmark research paper, published
in the English scientific journal Nature in 1985, probes to
minisatellite regions of human DNA produce “DNA ‘fingerprints’
which are completely specific to an individual (or to his or her identical
twin) and can be applied directly to problems of human identification,
including parenthood testing.”
Consequences
In addition to being used in human identification, DNA fingerprinting
has found applications in medical genetics. In the search
for a cause, a diagnostic test for, and ultimately the treatment of an
inherited disease, it is necessary to locate the defective gene on a human
chromosome. Gene location is accomplished by a technique
called “linkage analysis,” in which geneticists use marker sections
of DNA as reference points to pinpoint the position of a defective
gene on a chromosome. The minisatellite DNA probes developed
by Jeffreys provide a potent and valuable set of markers that are of
great value in locating disease-causing genes. Soon after its discovery,
DNA fingerprinting was used to locate the defective genes responsible
for several diseases, including fetal hemoglobin abnormality
and Huntington’s disease.
Genetic fingerprinting also has had a major impact on genetic
studies of higher animals. Because DNA sequences are conserved in
evolution, humans and other vertebrates have many sequences in
common. This commonality enabled Jeffreys to use his probes to
human minisatellites to bind to the DNA of many different verte-

ates, ranging from mammals to birds, reptiles, amphibians, and
fish; this made it possible for him to produce DNA fingerprints of
these vertebrates. In addition, the technique has been used to discern
the mating behavior of birds, to determine paternity in zoo primates,
and to detect inbreeding in imperiled wildlife. DNA fingerprinting
can also be applied to animal breeding problems, such as
the identification of stolen animals, the verification of semen samples
for artificial insemination, and the determination of pedigree.
The technique is not foolproof, however, and results may be far
from ideal. Especially in the area of forensic science, there was a
rush to use the tremendous power of DNA fingerprinting to identify
a purported murderer or rapist, and the need for scientific standards
was often neglected. Some problems arose because forensic
DNA fingerprinting in the United States is generally conducted in
private, unregulated laboratories. In the absence of rigorous scientific
controls, the DNA fingerprint bands of two completely unknown
samples cannot be matched precisely, and the results may be
unreliable.
See also Amniocentesis; Artificial chromosome; Cloning; In vitro
plant culture; Rice and wheat strains; Synthetic amino acid; Synthetic
DNA; Synthetic RNA.
Further Reading
Genetic “fingerprinting” / 373
Bodmer, Walter, and Robin McKie. “Probing the Present.” In The
Book of Man: The Human Genome Project. New York: Scribner, 1985.
Caetano-Anolles, Gustavo, and Peter M. Gresshoff. DNA Markers:
Protocols, Applications, and Overviews. New York: Wiley-VCH,
1997.
Krawezak, Michael, and Jorg Schmidtke. DNA Fingerprinting.2ded.
New York: Springer-Verlag, 1998.
Schacter, Bernice Zeldin. Issues and Dilemmas of Biotechnology: A Reference
Guide. Westport, Conn.: Greenwood Press, 1999.

374
Genetically engineered insulin
Genetically engineered insulin
The invention: Artificially manufactured human insulin (Humulin)
as a medication for people suffering from diabetes.
The people behind the invention:
Irving S. Johnson (1925- ), an American zoologist who was
vice president of research at Eli Lilly Research Laboratories
Ronald E. Chance (1934- ), an American biochemist at Eli
Lilly Research Laboratories
What Is Diabetes?
Carbohydrates (sugars and related chemicals) are the main food
and energy source for humans. In wealthy countries such as the
United States, more than 50 percent of the food people eat is made
up of carbohydrates, while in poorer countries the carbohydrate
content of diets is higher, from 70 to 90 percent.
Normally, most carbohydrates that a person eats are used (or metabolized)
quickly to produce energy. Carbohydrates not needed for
energy are either converted to fat or stored as a glucose polymer
called “glycogen.” Most adult humans carry about a pound of body
glycogen; this substance is broken down to produce energy when it
is needed.
Certain diseases prevent the proper metabolism and storage of
carbohydrates. The most common of these diseases is diabetes mellitus,
usually called simply “diabetes.” It is found in more than seventy
million people worldwide. Diabetic people cannot produce or
use enough insulin, a hormone secreted by the pancreas. When their
condition is not treated, the eyes may deteriorate to the point of
blindness. The kidneys may stop working properly, blood vessels
may be damaged, and the person may fall into a coma and die. In
fact, diabetes is the third most common killer in the United States.
Most of the problems surrounding diabetes are caused by high levels
of glucose in the blood. Cataracts often form in diabetics, as excess
glucose is deposited in the lens of the eye.
Important symptoms of diabetes include constant thirst, exces-

sive urination, and large amounts of sugar in the blood and in the
urine. The glucose tolerance test (GTT) is the best way to find out
whether a person is suffering from diabetes. People given a GTT are
first told to fast overnight. In the morning their blood glucose level
is measured; then they are asked to drink about a fourth of a pound
of glucose dissolved in water. During the next four to six hours, the
blood glucose level is measured repeatedly. In nondiabetics, glucose
levels do not rise above a certain amount during a GTT, and the
level drops quickly as the glucose is assimilated by the body. In diabetics,
the blood glucose levels rise much higher and do not drop as
quickly. The extra glucose then shows up in the urine.
Treating Diabetes
Genetically engineered insulin / 375
Until the 1920’s, diabetes could be controlled only through a diet
very low in carbohydrates, and this treatment was not always successful.
Then Sir Frederick G. Banting and Charles H. Best found a
way to prepare purified insulin from animal pancreases and gave it
to patients. This gave diabetics their first chance to live a fairly normal
life. Banting and his coworkers won the 1923 Nobel Prize in
Physiology or Medicine for their work.
The usual treatment for diabetics became regular shots of insulin.
Drug companies took the insulin from the pancreases of cattle and
pigs slaughtered by the meat-packing industry. Unfortunately, animal
insulin has two disadvantages. First, about 5 percent of diabetics
are allergic to it and can have severe reactions. Second, the world
supply of animal pancreases goes up and down depending on how
much meat is being bought. Between 1970 and 1975, the supply of
insulin fell sharply as people began to eat less red meat, yet the
numbers of diabetics continued to increase. So researchers began to
look for a better way to supply insulin.
Studying pancreases of people who had donated their bodies to
science, researchers found that human insulin did not cause allergic
reactions. Scientists realized that it would be best to find a chemical
or biological way to prepare human insulin, and pharmaceutical
companies worked hard toward this goal. Eli Lilly and Company
was the first to succeed, and on May 14, 1982, it filed a new drug application
with the Food and Drug Administration (FDA) for the hu-

376 / Genetically engineered insulin
man insulin preparation it named “Humulin.”
Humulin is made by genetic engineering. Irving S. Johnson, who
worked on the development of Humulin, described Eli Lilly’s method
for producing Humulin. The common bacterium Escherichia coli
is used. Two strains of the bacterium are produced by genetic engineering:
The first strain is used to make a protein called an “A
chain,” and the second strain is used to make a “B chain.” After the
bacteria are harvested, the A and B chains are removed and purified
separately. Then the two chains are combined chemically. When
they are purified once more, the result is Humulin, which has been
proved by Ronald E. Chance and his Eli Lilly coworkers to be chemically,
biologically, and physically identical to human insulin.
Consequences
The FDA and other regulatory agencies around the world approved
genetically engineered human insulin in 1982. Humulin
does not trigger allergic reactions, and its supply does not fluctuate.
It has brought an end to the fear that there would be a worldwide
shortage of insulin.
Humulin is important as well in being the first genetically engineered
industrial chemical. It began an era in which such advanced
technology could be a source for medical drugs, chemicals used in
farming, and other important industrial products. Researchers hope
that genetic engineering will help in the understanding of cancer
and other diseases, and that it will lead to ways to grow enough
food for a world whose population continues to rise.
See also Artificial chromosome; Artificial insemination; Cloning;
Genetic “fingerprinting”; Synthetic amino acid; Synthetic DNA;
Synthetic RNA.
Further Reading
Berger, Abi. “Gut Cells Engineered to Produce Insulin.” British Medical
Journal 321, no. 7275 (December 16, 2000).
“Genetically Engineered Duckweed to Produce Insulin.” Resource 6,
no. 3 (March, 1999).

Genetically engineered insulin / 377
“Lilly Gets FDA Approval for New Insulin Formula.” Wall Street
Journal (October 3, 1985).
Williams, Linda. “UC Regents Sue Lilly in Dispute Over Biotech
Patent for Insulin.” Los Angeles Times (February 8, 1990).

378
Geothermal power
Geothermal power
The invention: Energy generated from the earth’s natural hot
springs.
The people behind the invention:
Prince Piero Ginori Conti (1865-1939), an Italian nobleman and
industrialist
Sir Charles Parsons (1854-1931), an English engineer
B. C. McCabe, an American businessman
Developing a Practical System
The first successful use of geothermal energy was at Larderello in
northern Italy. The Larderello geothermal field, located near the city
of Pisa about 240 kilometers northwest of Rome, contains many hot
springs and fumaroles (steam vents). In 1777, these springs were
found to be rich in boron, and in 1818, Francesco de Larderel began
extracting the useful mineral borax from them. Shortly after 1900,
Prince Piero Ginori Conti, director of the Larderello borax works,
conceived the idea of using the steam for power production. An experimental
electrical power plant was constructed at Larderello in
1904 to provide electric power to the borax plant. After this initial
experiment proved successful, a 250-kilowatt generating station
was installed in 1913 and commercial power production began.
As the Larderello field grew, additional geothermal sites throughout
the region were prospected and tapped for power. Power production
grew steadily until the 1940’s, when production reached
130 megawatts; however, the Larderello power plants were destroyed
late in World War II (1939-1945). After the war, the generating
plants were rebuilt, and they were producing more than 400
megawatts by 1980.
The Larderello power plants encountered many of the technical
problems that were later to concern other geothermal facilities. For
example, hydrogen sulfide in the steam was highly corrosive to copper,
so the Larderello power plant used aluminum for electrical connections
much more than did conventional power plants of the

time. Also, the low pressure of the steam in early wells at Larderello
presented problems. The first generators simply used steam to drive
a generator and vented the spent steam into the atmosphere. A system
of this sort, called a “noncondensing system,” is useful for small
generators but not efficient to produce large amounts of power.
Most steam engines derive power not only from the pressure of
the steam but also from the vacuum created when the steam is condensed
back to water. Geothermal systems that generate power
from condensation, as well as direct steam pressure, are called “condensing
systems.” Most large geothermal generators are of this
type. Condensation of geothermal steam presents special problems
not present in ordinary steam engines: There are other gases present
that do not condense. Instead of a vacuum, condensation of steam
contaminated with other gases would result in only a limited drop
in pressure and, consequently, very low efficiency.
Initially, the operators of Larderello tried to use the steam to heat
boilers that would, in turn, generate pure steam. Eventually, a device
was developed that removed most of the contaminating gases from
the steam. Although later wells at Larderello and other geothermal
fields produced steam at greater pressure, these engineering innovations
improved the efficiency of any geothermal power plant.
Expanding the Idea
Geothermal power / 379
In 1913, the English engineer Sir Charles Parsons proposed drilling
an extremely deep (12-kilometer) hole to tap the earth’s deep
heat. Power from such a deep hole would not come from natural
steam as at Larderello but would be generated by pumping fluid
into the hole and generating steam (as hot as 500 degrees Celsius) at
the bottom. In modern terms, Parsons proposed tapping “hot dryrock”
geothermal energy. (No such plant has been commercially operated
yet, but research is being actively pursued in several countries.)
The first use of geothermal energy in the United States was for direct
heating. In 1890, the municipal water company of Boise, Idaho,
began supplying hot water from a geothermal well. Water was
piped from the well to homes and businesses along appropriately
named Warm Springs Avenue. At its peak, the system served more

380 / Geothermal power
than four hundred customers, but as cheap natural gas became
available, the number declined.
Although Larderello was the first successful geothermal electric
power plant, the modern era of geothermal electric power began
with the opening of the Geysers Geothermal Field in California.
Early attempts began in the 1920’s, but it was not until 1955 that B.
C. McCabe, a Los Angeles businessman, leased 14.6 square kilometers
in the Geysers area and founded the Magma Power Company.
The first 12.5-megawatt generator was installed at the Geysers in
1960, and production increased steadily from then on. The Geysers
surpassed Larderello as the largest producing geothermal field in
the 1970’s, and more than 1,000 megawatts were being generated by
1980. By the end of 1980, geothermal plants had been installed in
thirteen countries, with a total capacity of almost 2,600 megawatts,
and projects with a total capacity of more than 15,000 megawatts
were being planned in more than twenty countries.
Impact
Geothermal power has many attractive features. Because the
steam is naturally heated and under pressure, generating equipment
can be simple, inexpensive, and quickly installed. Equipment
and installation costs are offset by savings in fuel. It is economically
practical to install small generators, a fact that makes geothermal
plants attractive in remote or underdeveloped areas. Most important
to a world faced with a variety of technical and environmental
problems connected with fossil fuels, geothermal power does not
deplete fossil fuel reserves, produces little pollution, and contributes
little to the greenhouse effect.
Despite its attractive features, geothermal power has some limitations.
Geologic settings suitable for easy geothermal power production
are rare; there must be a hot rock or magma body close to
the surface. Although it is technically possible to pump water from
an external source into a geothermal well to generate steam, most
geothermal sites require a plentiful supply of natural underground
water that can be tapped as a source of steam. In contrast, fossil-fuel
generating plants can be at any convenient location.

See also Breeder reactor; Compressed-air-accumulating power
plant; Fuel cell; Heat pump; Nuclear power plant; Solar thermal engine;
Thermal cracking process; Tidal power plant.
Further Reading
Geothermal power / 381
Appleyard, Rollo. Charles Parsons: His Life and Work. London: Constable,
1933.
Boyle, Godfrey. Renewable Energy: Power for a Sustainable Future. Oxford:
Oxford University Press, 1998.
Cassedy, Edward S. Prospects for Sustainable Energy: A Critical Assessment.
New York: Cambridge University Press, 2000.
Parsons, Robert Hodson. The Steam Turbine and Other Inventions of
Sir Charles Parsons, O.M. New York: Longmans Green, 1946.

382
Gyrocompass
Gyrocompass
The invention: The first practical navigational device that enabled
ships and submarines to stay on course without relying on the
earth’s unreliable magnetic poles.
The people behind the invention:
Hermann Anschütz-Kaempfe (1872-1931), a German inventor
and manufacturer
Jean-Bernard-Léon Foucault (1819-1868), a French experimental
physicist and inventor
Elmer Ambrose Sperry (1860-1930), an American engineer and
inventor
From Toys to Tools
A gyroscope consists of a rapidly spinning wheel mounted in a
frame that enables the wheel to tilt freely in any direction. The
amount of momentum allows the wheel to maintain its “attitude”
even when the whole device is turned or rotated.
These devices have been used to solve problems arising in such
areas as sailing and navigation. For example, a gyroscope aboard a
ship maintains its orientation even while the ship is rolling. Among
other things, this allows the extent of the roll to be measured accurately.
Moreover, the spin axis of a free gyroscope can be adjusted to
point toward true north. It will (with some exceptions) stay that
way despite changes in the direction of a vehicle in which it is
mounted. Gyroscopic effects were employed in the design of various
objects long before the theory behind them was formally
known. A classic example is a child’s top, which balances, seemingly
in defiance of gravity, as long as it continues to spin. Boomerangs
and flying disks derive stability and accuracy from the spin
imparted by the thrower. Likewise, the accuracy of rifles improved
when barrels were manufactured with internal spiral grooves that
caused the emerging bullet to spin.
In 1852, the French inventor Jean-Bernard-Léon Foucault built
the first gyroscope, a measuring device consisting of a rapidly spinning
wheel mounted within concentric rings that allowed the wheel

to move freely about two axes. This device, like the Foucault pendulum,
was used to demonstrate the rotation of the earth around its
axis, since the spinning wheel, which is not fixed, retains its orientation
in space while the earth turns under it. The gyroscope had a related
interesting property: As it continued to spin, the force of the
earth’s rotation caused its axis to rotate gradually until it was oriented
parallel to the earth’s axis, that is, in a north-south direction. It
is this property that enables the gyroscope to be used as a compass.
When Magnets Fail
Gyrocompass / 383
In 1904, Hermann Anschütz-Kaempfe, a German manufacturer
working in the Kiel shipyards, became interested in the navigation
problems of submarines used in exploration under the polar ice cap.
By 1905, efficient working submarines were a reality, and it was evident
to all major naval powers that submarines would play an increasingly
important role in naval strategy.
Submarine navigation posed problems, however, that could not
be solved by instruments designed for surface vessels. A submarine
needs to orient itself under water in three dimensions; it has no automatic
horizon with respect to which it can level itself. Navigation
by means of stars or landmarks is impossible when the submarine is
submerged. Furthermore, in an enclosed metal hull containing machinery
run by electricity, a magnetic compass is worthless. To a
lesser extent, increasing use of metal, massive moving parts, and
electrical equipment had also rendered the magnetic compass unreliable
in conventional surface battleships.
It made sense for Anschütz-Kaempfe to use the gyroscopic effect
to design an instrument that would enable a ship to maintain its
course while under water. Yet producing such a device would not be
easy. First, it needed to be suspended in such a way that it was free to
turn in any direction with as little mechanical resistance as possible.
At the same time, it had to be able to resist the inevitable pitching and
rolling of a vessel at sea. Finally, a continuous power supply was required
to keep the gyroscopic wheels spinning at high speed.
The original Anschütz-Kaempfe gyrocompass consisted of a pair
of spinning wheels driven by an electric motor. The device was connected
to a compass card visible to the ship’s navigator. Motor, gyro-

384 / Gyrocompass
Elmer Sperry
Although Elmer Ambrose Sperry, born in 1860, had only a
grade school education as a child in rural New York, the equipment
used on local farms piqued his interest in machinery and
he learned about technology on his own. He attended a local
teachers’ college, and graduating in 1880, he was determined to
become an inventor.
He was especially interested in the application of electricity.
He designed his own arc lighting system and opened the Sperry
Electric Light, Motor, and Car Brake Company to sell it, changing
its name to Sperry Electric Company in 1887. He made such
progress in devising electric mining equipment, electric brakes
for automobiles and streetcars, and his own electric car that
General Electric bought him out.
In 1900 Sperry opened a laboratory in Washington, D.C., and
continued research on a gyroscope that he began in 1896. After
more than a decade he patented his device, and after successful
trials aboard the USS Worden, he established the Sperry Gyroscope
Company in 1910, later supplying the American, British,
and Russian navies as well as commercial ships. In 1914 he
successfully demonstrated a gyrostabilizer for aircraft and expanded
his company to manufacture aeronautical technology.
Before he sold the company in 1926 he had registered more than
four hundred patents. Sperry died in Brooklyn in 1930.
scope, and suspension system were mounted in a frame that allowed
the apparatus to remain stable despite the pitch and roll of the ship.
In 1906, the German navy installed a prototype of the Anschütz-
Kaempfe gyrocompass on the battleship Undine and subjected it to
exhaustive tests under simulated battle conditions, sailing the ship
under forced draft and suddenly reversing the engines, changing the
position of heavy turrets and other mechanisms, and firing heavy
guns. In conditions under which a magnetic compass would have
been worthless, the gyrocompass proved a satisfactory navigational
tool, and the results were impressive enough to convince the German
navy to undertake installation of gyrocompasses in submarines and
heavy battleships, including the battleship Deutschland.
Elmer Ambrose Sperry, a New York inventor intimately associated
with pioneer electrical development, was independently work-

ing on a design for a gyroscopic compass at about the same time.
In 1907, he patented a gyrocompass consisting of a single rotor
mounted within two concentric shells, suspended by fine piano
wire from a frame mounted on gimbals. The rotor of the Sperry
compass operated in a vacuum, which enabled it to rotate more
rapidly. The Sperry gyrocompass was in use on larger American
battleships and submarines on the eve of World War I (1914-1918).
Impact
The ability to navigate submerged submarines was of critical
strategic importance in World War I. Initially, the German navy
had an advantage both in the number of submarines at its disposal
and in their design and maneuverability. The German U-boat fleet
declared all-out war on Allied shipping, and, although their efforts
to blockade England and France were ultimately unsuccessful, the
tremendous toll they inflicted helped maintain the German position
and prolong the war. To a submarine fleet operating throughout
the Atlantic and in the Caribbean, as well as in near-shore European
waters, effective long-distance navigation was critical.
Gyrocompasses were standard equipment on submarines and
battleships and, increasingly, on larger commercial vessels during
World War I, World War II (1939-1945), and the period between the
wars. The devices also found their way into aircraft, rockets, and
guided missiles. Although the compasses were made more accurate
and easier to use, the fundamental design differed little from that invented
by Anschütz-Kaempfe.
See also Atomic-powered ship; Dirigible; Hovercraft; Radar; Sonar.
Further Reading
Gyrocompass / 385
Hughes, Thomas Parke. Elmer Sperry: Inventor and Engineer. Baltimore:
Johns Hopkins University Press, 1993.
_____. Science and the Instrument-Maker: Michelson, Sperry, and the
Speed of Light. Washington: Smithsonian Institution Press, 1976.
Sorg, H. W. “From Serson to Draper: Two Centuries of Gyroscopic
Development.” Journal of the Institute of Navigation 23, no. 4 (Winter,
1976-1977).

386
Hard disk
Hard disk
The invention: A large-capacity, permanent magnetic storage device
built into most personal computers.
The people behind the invention:
Alan Shugart (1930- ), an engineer who first developed the
floppy disk
Philip D. Estridge (1938?-1985), the director of IBM’s product
development facility
Thomas J. Watson, Jr. (1914-1993), the chief executive officer of
IBM
The Personal Oddity
When the International Business Machines (IBM) Corporation
introduced its first microcomputer, called simply the IBM PC (for
“personal computer”), the occasion was less a dramatic invention
than the confirmation of a trend begun some years before. A number
of companies had introduced microcomputers before IBM; one
of the best known at that time was Apple Corporation’s Apple II, for
which software for business and scientific use was quickly developed.
Nevertheless, the microcomputer was quite expensive and
was often looked upon as an oddity, not as a useful tool.
Under the leadership of Thomas J. Watson, Jr., IBM, which had
previously focused on giant mainframe computers, decided to develop
the PC. A design team headed by Philip D. Estridge was assembled
in Boca Raton, Florida, and it quickly developed its first,
pacesetting product. It is an irony of history that IBM anticipated
selling only one hundred thousand or so of these machines, mostly
to scientists and technically inclined hobbyists. Instead, IBM’s product
sold exceedingly well, and its design parameters, as well as its
operating system, became standards.
The earliest microcomputers used a cassette recorder as a means
of mass storage; a floppy disk drive capable of storing approximately
160 kilobytes of data was initially offered only as an option.
While home hobbyists were accustomed to using a cassette recorder

for storage purposes, such a system was far too slow and awkward
for use in business and science. As a result, virtually every IBM PC
sold was equipped with at least one 5.25-inch floppy disk drive.
Memory Requirements
Hard disk / 387
All computers require memory of two sorts in order to carry out
their tasks. One type of memory is main memory, or random access
memory (RAM), which is used by the computer’s central processor
to store data it is using while operating. The type of memory used
for this function is built typically of silicon-based integrated circuits
that have the advantage of speed (to allow the processor to fetch or
store the data quickly), but the disadvantage of possibly losing or
“forgetting” data when the electric current is turned off. Further,
such memory generally is relatively expensive.
To reduce costs, another type of memory—long-term storage
memory, known also as “mass storage”—was developed. Mass
storage devices include magnetic media (tape or disk drives) and
optical media (such as the compact disc, read-only memory, or CD-
ROM). While the speed with which data may be retrieved from or
stored in such devices is rather slow compared to the central processor’s
speed, a disk drive—the most common form of mass storage
used in PCs—can store relatively large amounts of data quite inexpensively.
Early floppy disk drives (so called because the magnetically
treated material on which data are recorded is made of a very flexible
plastic) held 160 kilobytes of data using only one side of the
magnetically coated disk (about eighty pages of normal, doublespaced,
typewritten information). Later developments increased
storage capacities to 360 kilobytes by using both sides of the disk
and later, with increasing technological ability, 1.44 megabytes (millions
of bytes). In contrast, mainframe computers, which are typically
connected to large and expensive tape drive storage systems,
could store gigabytes (millions of megabytes) of information.
While such capacities seem large, the needs of business and scientific
users soon outstripped available space. Since even the mailing
list of a small business or a scientist’s mathematical model of a
chemical reaction easily could require greater storage potential than

388 / Hard disk
early PCs allowed, the need arose for a mass storage device that
could accommodate very large files of data.
The answer was the hard disk drive, also known as a “fixed disk
drive,” reflecting the fact that the disk itself is not only rigid but also
permanently installed inside the machine. In 1955, IBM had envisioned
the notion of a fixed, hard magnetic disk as a means of storing
computer data, and, under the direction of Alan Shugart in the
1960’s, the floppy disk was developed as well.
As the engineers of IBM’s facility in Boca Raton refined the idea
of the original PC to design the new IBM PC XT, it became clear that
chief among the needs of users was the availability of large-capability
storage devices. The decision was made to add a 10-megabyte
hard disk drive to the PC. On March 8, 1983, less than two years after
the introduction of its first PC, IBM introduced the PC XT. Like
the original, it was an evolutionary design, not a revolutionary one.
The inclusion of a hard disk drive, however, signaled that mass storage
devices in personal computers had arrived.
Consequences
Above all else, any computer provides a means for storing, ordering,
analyzing, and presenting information. If the personal computer
is to become the information appliance some have suggested
it will be, the ability to manipulate very large amounts of data will
be of paramount concern. Hard disk technology was greeted enthusiastically
in the marketplace, and the demand for hard drives has
seen their numbers increase as their quality increases and their
prices drop.
It is easy to understand one reason for such eager acceptance:
convenience. Floppy-bound computer users find themselves frequently
changing (or “swapping”) their disks in order to allow programs
to find the data they need. Moreover, there is a limit to how
much data a single floppy disk can hold. The advantage of a hard
drive is that it allows users to keep seemingly unlimited amounts of
data and programs stored in their machines and readily available.
Also, hard disk drives are capable of finding files and transferring
their contents to the processor much more quickly than a
floppy drive. A user may thus create exceedingly large files, keep

them on hand at all times, and manipulate data more quickly than
with a floppy. Finally, while a hard drive is a slow substitute for
main memory, it allows users to enjoy the benefits of larger memories
at significantly lower cost.
The introduction of the PC XT with its 10-megabyte hard drive
was a milestone in the development of the PC. Over the next two decades,
the size of computer hard drives increased dramatically. By
2001, few personal computers were sold with hard drives with less
than three gigabytes of storage capacity, and hard drives with more
than thirty gigabytes were becoming the standard. Indeed, for less
money than a PC XT cost in the mid-1980’s, one could buy a fully
equipped computer with a hard drive holding sixty gigabytes—a
storage capacity equivalent to six thousand 10-megabyte hard drives.
See also Bubble memory; Compact disc; Computer chips;
Floppy disk; Optical disk; Personal computer.
Further Reading
Hard disk / 389
Chposky, James, and Ted Leonsis. Blue Magic: The People, Power, and
Politics Behind the IBM Personal Computer. New York: Facts on File,
1988.
Freiberger, Paul, and Michael Swaine. Fire in the Valley: The Making of
the Personal Computer. 2d ed. New York: McGraw-Hill, 2000.
Grossman, Wendy. Remembering the Future: Interviews from Personal
Computer World. New York: Springer, 1997.
Watson, Thomas J., and Peter Petre. Father, Son and Co.: My Life at
IBM and Beyond. New York: Bantam Books, 2000.

390
Hearing aid
Hearing aid
The invention: Miniaturized electronic amplifier worn inside the
ears of hearing-impaired persons.
The organization behind the invention:
Bell Labs, the research and development arm of the American
Telephone and Telegraph Company
Trapped in Silence
Until the middle of the twentieth century, people who experienced
hearing loss had little hope of being able to hear sounds without the
use of large, awkward, heavy appliances. For many years, the only
hearing aids available were devices known as ear trumpets. The ear
trumpet tried to compensate for hearing loss by increasing the number
of sound waves funneled into the ear canal. A wide, bell-like
mouth similar to the bell of a musical trumpet narrowed to a tube that
the user placed in his or her ear. Ear trumpets helped a little, but they
could not truly increase the volume of the sounds heard.
Beginning in the nineteenth century, inventors tried to develop
electrical devices that would serve as hearing aids. The telephone
was actually a by-product of Alexander Graham Bell’s efforts to
make a hearing aid. Following the invention of the telephone, electrical
engineers designed hearing aids that employed telephone
technology, but those hearing aids were only a slight improvement
over the old ear trumpets. They required large, heavy battery packs
and used a carbon microphone similar to the receiver in a telephone.
More sensitive than purely physical devices such as the ear trumpet,
they could transmit a wider range of sounds but could not amplify
them as effectively as electronic hearing aids now do.
Transistors Make Miniaturization Possible
Two types of hearing aids exist: body-worn and head-worn.
Body-worn hearing aids permit the widest range of sounds to be
heard, but because of the devices’ larger size, many hearing-

Hearing aid / 391
impaired persons do not like to wear them. Head-worn hearing
aids, especially those worn completely in the ear, are much less conspicuous.
In addition to in-ear aids, the category of head-worn hearing
aids includes both hearing aids mounted in eyeglass frames and
those worn behind the ear.
All hearing aids, whether head-worn or body-worn, consist of
four parts: a microphone to pick up sounds, an amplifier, a receiver,
and a power source. The microphone gathers sound waves and converts
them to electrical signals; the amplifier boosts, or increases,
those signals; and the receiver then converts the signals back into
sound waves. In effect, the hearing aid is a miniature radio. After
the receiver converts the signals back to sound waves, those waves
are directed into the ear canal through an earpiece or ear mold. The
ear mold generally is made of plastic and is custom fitted from an
impression taken from the prospective user’s ear.
Effective head-worn hearing aids could not be built until the
electronic circuit was developed in the early 1950’s. The same invention—the
transistor—that led to small portable radios and tape
players allowed engineers to create miniaturized, inconspicuous
hearing aids. Depending on the degree of amplification required,
the amplifier in a hearing aid contains three or more transistors.
Transistors first replaced vacuum tubes in devices such as radios
and phonographs, and then engineers realized that they could be
used in devices for the hearing-impaired.
The research at Bell Labs that led to the invention of the transistor
rose out of military research during World War II. The vacuum tubes
used in, for example, radar installations to amplify the strength of electronic
signals were big, were fragile because they were made of
blown glass, and gave off high levels of heat when they were used.
Transistors, however, made it possible to build solid-state, integrated
circuits. These are made from crystals of metals such as germanium
or arsenic alloys and therefore are much less fragile than glass. They
are also extremely small (in fact, some integrated circuits are barely
visible to the naked eye) and give off no heat during use.
The number of transistors in a hearing aid varies depending upon
the amount of amplification required. The first transistor is the most
important for the listener in terms of the quality of sound heard. If the
frequency response is set too high—that is, if the device is too sensi-

392 / Hearing aid
tive—the listener will be bothered by distracting background noise.
Theoretically, there is no limit on the amount of amplification that a
hearing aid can be designed to provide, but there are practical limits.
The higher the amplification, the more power is required to operate
the hearing aid. This is why body-worn hearing aids can convey a
wider range of sounds than head-worn devices can. It is the power
source—not the electronic components—that is the limiting factor. A
body-worn hearing aid includes a larger battery pack than can be
used with a head-worn device. Indeed, despite advances in battery
technology, the power requirements of a head-worn hearing aid are
such that a 1.4-volt battery that could power a wristwatch for several
years will last only a few days in a hearing aid.
Consequences
The invention of the electronic hearing aid made it possible for
many hearing-impaired persons to participate in a hearing world.
Prior to the invention of the hearing aid, hearing-impaired children
often were unable to participate in routine school activities or function
effectively in mainstream society. Instead of being able to live at
home with their families and enjoy the same experiences that were
available to other children their age, often they were forced to attend
special schools operated by the state or by charities.
Hearing-impaired people were singled out as being different and
were limited in their choice of occupations. Although not every
hearing-impaired person can be helped to hear with a hearing aid—
particularly in cases of total hearing loss—the electronic hearing aid
has ended restrictions for many hearing-impaired people. Hearingimpaired
children are now included in public school classes, and
hearing-impaired adults can now pursue occupations from which
they were once excluded.
Today, many deaf and hearing-impaired persons have chosen to
live without the help of a hearing aid. They believe that they are not
disabled but simply different, and they point out that their “disability”
often allows them to appreciate and participate in life in unique
and positive ways. For them, the use of hearing aids is a choice, not a
necessity. For those who choose, hearing aids make it possible to
participate in the hearing world.

See also Artificial heart; Artificial kidney; Cell phone; Contact
lenses; Heart-lung machine; Pacemaker.
Further Reading
Hearing aid / 393
Alexander, Howard. “Hearing Aids: Smaller and Smarter.” New
York Times (November 26, 1998).
Fong, Petti. “Guess What’s the New Buzz in Hearing Aids.” Business
Week, no. 3730 (April 30, 2001).
Levitt, Harry. “Noise Reduction in Hearing Aids: AReview.” Journal
of Rehabilitation Research and Development 38, no. 1 (January/February,
2001).

394
Heart-lung machine
Heart-lung machine
The invention: The first artificial device to oxygenate and circulate
blood during surgery, the heart-lung machine began the era of
open-heart surgery.
The people behind the invention:
John H. Gibbon, Jr. (1903-1974), a cardiovascular surgeon
Mary Hopkinson Gibbon (1905- ), a research technician
Thomas J. Watson (1874-1956), chairman of the board of IBM
T. L. Stokes and J. B. Flick, researchers in Gibbon’s laboratory
Bernard J. Miller (1918- ), a cardiovascular surgeon and
research associate
Cecelia Bavolek, the first human to undergo open-heart surgery
successfully using the heart-lung machine
A Young Woman’s Death
In the first half of the twentieth century, cardiovascular medicine
had many triumphs. Effective anesthesia, antiseptic conditions, and
antibiotics made surgery safer. Blood-typing, anti-clotting agents,
and blood preservatives made blood transfusion practical. Cardiac
catheterization (feeding a tube into the heart), electrocardiography,
and fluoroscopy (visualizing living tissues with an X-ray machine)
made the nonsurgical diagnosis of cardiovascular problems possible.
As of 1950, however, there was no safe way to treat damage or defects
within the heart. To make such a correction, this vital organ’s
function had to be interrupted. The problem was to keep the body’s
tissues alive while working on the heart. While some surgeons practiced
so-called blind surgery, in which they inserted a finger into the
heart through a small incision without observing what they were attempting
to correct, others tried to reduce the body’s need for circulation
by slowly chilling the patient until the heart stopped. Still other
surgeons used “cross-circulation,” in which the patient’s circulation
was connected to a donor’s circulation. All these approaches carried
profound risks of hemorrhage, tissue damage, and death.
In February of 1931, Gibbon witnessed the death of a young

woman whose lung circulation was blocked by a blood clot. Because
her blood could not pass through her lungs, she slowly lost
consciousness from lack of oxygen. As he monitored her pulse and
breathing, Gibbon thought about ways to circumvent the obstructed
lungs and straining heart and provide the oxygen required. Because
surgery to remove such a blood clot was often fatal, the woman’s
surgeons operated only as a last resort. Though the surgery took
only six and one-half minutes, she never regained consciousness.
This experience prompted Gibbon to pursue what few people then
considered a practical line of research: a way to circulate and oxygenate
blood outside the body.
A Woman’s Life Restored
Heart-lung machine / 395
Gibbon began the project in earnest in 1934, when he returned to
the laboratory of Edward D. Churchill at Massachusetts General
Hospital for his second surgical research fellowship. He was assisted
by Mary Hopkinson Gibbon. Together, they developed, using
cats, a surgical technique for removing blood from a vein, supplying
the blood with oxygen, and returning it to an artery using tubes inserted
into the blood vessels. Their objective was to create a device
that would keep the blood moving, spread it over a very thin layer
to pick up oxygen efficiently and remove carbon dioxide, and avoid
both clotting and damaging blood cells. In 1939, they reported that
prolonged survival after heart-lung bypass was possible in experimental
animals.
World War II (1939-1945) interrupted the progress of this work; it
was resumed by Gibbon at Jefferson Medical College in 1944. Shortly
thereafter, he attracted the interest of Thomas J. Watson, chairman of
the board of the International Business Machines (IBM) Corporation,
who provided the services of IBM’s experimental physics laboratory
and model machine shop as well as the assistance of staff engineers.
IBM constructed and modified two experimental machines
over the next seven years, and IBM engineers contributed significantly
to the evolution of a machine that would be practical in humans.
Gibbon’s first attempt to use the pump-oxygenator in a human
being was in a fifteen-month-old baby. This attempt failed, not be-

396 / Heart-lung machine
cause of a malfunction or a surgical mistake but because of a misdiagnosis.
The child died following surgery because the real problem
had not been corrected by the surgery.
On May 6, 1953, the heart-lung machine was first used successfully
on Cecelia Bavolek. In the six months before surgery, Bavolek
had been hospitalized three times for symptoms of heart failure
when she tried to engage in normal activity. While her circulation
was connected to the heart-lung machine for forty-five minutes, the
surgical team headed by Gibbon was able to close an opening between
her atria and establish normal heart function. Two months
later, an examination of the defect revealed that it was fully closed;
Bavolek resumed a normal life. The age of open-heart surgery had
begun.
Consequences
The heart-lung bypass technique alone could not make openheart
surgery truly practical. When it was possible to keep tissues
alive by diverting blood around the heart and oxygenating it, other
questions already under investigation became even more critical:
how to prolong the survival of bloodless organs, how to measure
oxygen and carbon dioxide levels in the blood, and how to prolong
anesthesia during complicated surgery. Thus, following the first
successful use of the heart-lung machine, surgeons continued to refine
the methods of open-heart surgery.
The heart-lung apparatus set the stage for the advent of “replacement
parts” for many types of cardiovascular problems. Cardiac
valve replacement was first successfully accomplished in 1960 by
placing an artificial ball valve between the left atrium and ventricle.
In 1957, doctors performed the first coronary bypass surgery, grafting
sections of a leg vein into the heart’s circulation system to divert
blood around clogged coronary arteries. Likewise, the first successful
heart transplant (1967) and the controversial Jarvik-7 artificial
heart implantation (1982) required the ability to stop the heart and
keep the body’s tissues alive during time-consuming and delicate
surgical procedures. Gibbon’s heart-lung machine paved the way
for all these developments.

See also Artificial heart; Blood transfusion; CAT scanner; Coronary
artery bypass surgery; Electrocardiogram; Iron lung; Mammography;
Nuclear magnetic resonance; Pacemaker; X-ray image
intensifier.
Further Reading
Heart-lung machine / 397
DeJauregui, Ruth. One Hundred Medical Milestones That Shaped World
History. San Mateo, Calif.: Bluewood Books, 1998.
Romaine-Davis, Ada. John Gibbon and his Heart-Lung Machine. Philadelphia:
University of Pennsylvania Press, 1991.
Shumacker, Harris B. A Dream of the Heart: The Life of John H. Gibbon,
Jr., Father of the Heart-Lung Machine. Santa Barbara, Calif.: Fithian
Press, 1999.
Watson, Thomas J., and Peter Petre. Father, Son and Co.: My Life at
IBM and Beyond. New York: Bantam Books, 2000.

398
Heat pump
Heat pump
The invention: A device that warms and cools buildings efficiently
and cheaply by moving heat from one area to another.
The people behind the invention:
T. G. N. Haldane, a British engineer
Lord Kelvin (William Thomson, 1824-1907), a British
mathematician, scientist, and engineer
Sadi Carnot (1796-1832), a French physicist and
thermodynamicist
The Heat Pump
A heat pump is a device that takes in heat at one temperature and
releases it at a higher temperature. When operated to provide heat (for
example, for space heating), the heat pump is said to operate in the
heating mode; when operated to remove heat (for example, for air conditioning),
it is said to operate in the cooling mode. Some type of work
must be done to drive the pump, no matter which mode is being used.
There are two general types of heat pumps: vapor compression
pumps and absorption pumps. The basic principle of vapor compression
cycle heat pumps is derived from the work of Sadi Carnot
in the early nineteenth century. Carnot’s work was published in
1824. It was William Thomson (later to become known as Lord Kelvin),
however, who first proposed a practical heat pump system, or
“heat multiplier,” as it was known then, and he also indicated that a
refrigerating machine could be used for heating.
Thomson’s heat pump used air as its working fluid. Thomson
claimed that his heat pump was able to produce heat by using only
3 percent of the energy that would be required for direct heating.
Absorption cycle machines have an even longer history. Refrigerators
based on the use of sulfuric acid and water date back to 1777.
Systems using this fluid combination, improved and modified by
Edmond Carré, were used extensively in Paris cafés in the late
1800’s. In 1849, a patent was filed by Ferdinand Carré for the working-fluid
pair of ammonia and water in absorption cycle machines.

Refrigerator or Heater
Heat pump / 399
In the early nineteenth century, many people (including some
electrical engineers) believed that electrical energy could never be
used economically to produce large quantities of heat under ordinary
conditions. A few researchers, however, believed that it was
possible to produce heat by using electrical energy if that energy
was first converted to mechanical energy and if the Carnot principle
was then used to pump heat from a lower to a higher temperature.
In 1927, T. G. N. Haldane carried out detailed experiments showing
that the heat pump can be made to operate in either the heating
mode or the cooling mode. A heat pump in the cooling mode works
like a refrigerator; a heat pump in the heating mode supplies heat
for heating. Haldane demonstrated that a refrigerator could be
modified to work as a heating unit. He used a vapor compression
cycle refrigerator for his demonstration.
In the design of a refrigerating device, the primary objective is
the production of cold rather than heat, but the two operations are
complementary. The process of producing cold is simply that of
pumping heat from a relatively cold to a relatively hot source, but in
the refrigeration process particular attention is paid to the prevention
of the leakage of heat into the cold source, whereas no attempt
is made to prevent the escape of heat from the hot source. If a refrigerating
device were treated as a heat pump in which the primary
product is the heat rejected to the hot source, the order of importance
would be reversed, and every opportunity would be taken to
allow heat to leak into the cold source and every precaution would
be taken against allowing heat to leak out of the hot source.
The components of a heat pump that operates on the principle of
vapor compression include an electric motor, a compressor, an evaporator,
and a condenser. The compressor sucks in gas from the evaporator
and compresses it to a pressure that corresponds to a saturation
temperature that is slightly higher than that of the required heat. From
the compressor, the compressed gas passes to the condenser, where it is
cooled and condensed, thereby giving up a large quantity of heat to the
water or other substance that it is intended to heat. The condensed gas
then passes through the expansion valve, where a sudden reduction of
pressure takes place. This reduction of pressure lowers the boiling

400 / Heat pump
point of the liquid, which therefore vaporizes and takes in heat from
the medium surrounding the evaporator. After evaporation, the gas
passes on to the compressor, and the cycle is complete.
Haldane was the first person in the United Kingdom to install a
heat pump. He was also the first person to install a domestic heat
pump to provide hot water and space heating.
Heat In
Impact
Low-Pressure
Vapor
Electric Power
High-Pressure
Vapor
Compressor
Evaporator Condenser
Low-Pressure
Liquid
Expansion Valve
Components of a heat pump.
High-Pressure
Liquid
Heat Out
Since Haldane’s demonstration of the use of the heat pump, the
device has been highly successful in people’s homes, especially in
those regions where both heating and cooling are required for single-
and multifamily residences (for example, Australia, Japan, and
the United States). This is the case because the heat pump can provide
both heating and cooling; therefore, the cost of a heat pump
system can be spread over both heating and cooling seasons. Total
annual sales of heat pumps worldwide have risen to the millions,
with most sales being made in Japan and the United States.
The use of heat pumps can save energy. In addition, because they
are electric, they can save significant quantities of oil, especially in
the residential retrofit and replacement markets and when used as
add-on devices for existing heating systems. Some heat pumps are
now available that may compete cost-effectively with other heating
systems in meeting the heating demands of cooler regions.

Technological developments by heat pump manufacturers are
continually improving the performance and cost-effectiveness of
heat pumps. The electric heat pump will continue to dominate the
residential market, although engine-driven systems are likely to
have a greater impact on the multifamily market.
See also Breeder reactor; Compressed-air-accumulating power
plant; Fuel cell; Geothermal power; Nuclear power plant; Solar
thermal engine; Tidal power plant.
Further Reading
Heat pump / 401
Kavanaugh, Stephen P., and Kevin D. Rafferty. Ground-Source Heat
Pumps: Design of Geothermal Systems for Commercial and Institutional
Buildings. Atlanta: American Society of Heating, Refrigerating
and Air-Conditioning Engineers, 1997.
Nisson, Ned. “Efficient and Affordable.” Popular Science 247, no. 2
(August, 1995).
Using the Earth to Heat and Cool Homes. Washington, D.C.: U.S. Department
of Energy, 1983.

402
Holography
Holography
The invention: A lensless system of three-dimensional photography
that was one of the most important developments in twentieth
century optical science.
The people behind the invention:
Dennis Gabor (1900-1979), a Hungarian-born inventor and
physicist who was awarded the 1971 Nobel Prize in Physics
Emmett Leith (1927- ), a radar researcher who, with Juris
Upatnieks, produced the first laser holograms
Juris Upatnieks (1936- ), a radar researcher who, with
Emmett Leith, produced the first laser holograms
Easter Inspiration
The development of photography in the early 1900’s made possible
the recording of events and information in ways unknown before
the twentieth century: the photographing of star clusters, the
recording of the emission spectra of heated elements, the storing of
data in the form of small recorded images (for example, microfilm),
and the photographing of microscopic specimens, among other
things. Because of its vast importance to the scientist, the science of
photography has developed steadily.
An understanding of the photographic and holographic processes
requires some knowledge of the wave behavior of light. Light is an
electromagnetic wave that, like a water wave, has an amplitude and a
phase. The amplitude corresponds to the wave height, while the
phase indicates which part of the wave is passing a given point at a
given time. A cork floating in a pond bobs up and down as waves
pass under it. The position of the cork at any time depends on both
amplitude and phase: The phase determines on which part of the
wave the cork is floating at any given time, and the amplitude determines
how high or low the cork can be moved. Waves from more
than one source arriving at the cork combine in ways that depend on
their relative phases. If the waves meet in the same phase, they add
and produce a large amplitude; if they arrive out of phase, they sub-

tract and produce a small amplitude. The total amplitude, or intensity,
depends on the phases of the combining waves.
Dennis Gabor, the inventor of holography, was intrigued by the
way in which the photographic image of an object was stored by a
photographic plate but was unable to devote any consistent research
effort to the question until the 1940’s. At that time, Gabor was involved
in the development of the electron microscope. On Easter
morning in 1947, as Gabor was pondering the problem of how to
improve the electron microscope, the solution came to him. He
would attempt to take a poor electron picture and then correct it optically.
The process would require coherent electron beams—that is,
electron waves with a definite phase.
This two-stage method was inspired by the work of Lawrence
Bragg. Bragg had formed the image of a crystal lattice by diffracting
the photographic X-ray diffraction pattern of the original lattice.
This double diffraction process is the basis of the holographic process.
Bragg’s method was limited because of his inability to record
the phase information of the X-ray photograph. Therefore, he could
study only those crystals for which the phase relationship of the reflected
waves could be predicted.
Waiting for the Laser
Holography / 403
Gabor devised a way of capturing the phase information after he
realized that adding coherent background to the wave reflected from
an object would make it possible to produce an interference pattern
on the photographic plate. When the phases of the two waves are
identical, a maximum intensity will be recorded; when they are out of
phase, a minimum intensity is recorded. Therefore, what is recorded
in a hologram is not an image of the object but rather the interference
pattern of the two coherent waves. This pattern looks like a collection
of swirls and blank spots. The hologram (or photograph) is then illuminated
by the reference beam, and part of the transmitted light is a
replica of the original object wave. When viewing this object wave,
one sees an exact replica of the original object.
The major impediment at the time in making holograms using
any form of radiation was a lack of coherent sources. For example,
the coherence of the mercury lamp used by Gabor and his assistant

404 / Holography
Dennis Gabor
The eldest son of a mine director, Dennis Gabor was born in
1900 in Budapest, Hungary. At fifteen, suddenly developing
an intense interest in optics and photography, Gabor and his
brother sent up their own home laboratory and experimented
in those fields as well as with X rays and radioactivity. The love
of physics never left him.
Gabor graduated from the Berlin Technische Hochschule in
1924 and earned a doctorate of engineering in 1927 after developing
a high-speed cathode ray oscillograph and a new kind of
magnetic lens for controlling electrons. After graduate school
he joined Siemens and Halske Limited and invented a highpressure
mercury lamp, which was later used widely in street
lamps. In 1933, Gabor left Germany because of the rise of Nazism
and moved to England. He worked in industrial research
until 1948, improving gas-discharge tubes and stereoscopic cinematography,
but he also published scientific papers on his
own, including the first of many on communications theory. At
the beginning of 1949, Gabor became a faculty member of the
Imperial College of Science and Technology in London, first as a
reader in electronics and later as a professor of applied physics.
During his academic years came more inventions, including
the hologram, an electron-velocity spectroscope, an analog computer,
a flat color television tube, and a new type of thermionic
converter. He also build a cloud chamber for detecting subatomic
particles and used it to study electron interactions. As
interested in theory as he was in applied physics, Gabor
published papers on theoretical aspects of communications,
plasma, magnetrons, and fusion. In his later years he worried
deeply about the modern tendency for technology to advance
out of step with social institutions and wrote popular books
outlining his belief that social reform should be given priority.
Gabor became a member of Britain’s Royal Society in 1956
and was awarded its Rumsford Medal in 1968. In 1971 he received
the Nobel Prize in Physics for inventing holography. He
died in London in 1979.

Ivor Williams was so short that they were able to make holograms of
only about a centimeter in diameter. The early results were rather
poor in terms of image quality and also had a double image. For this
reason, there was little interest in holography, and the subject lay almost
untouched for more than ten years.
Interest in the field was rekindled after the laser (light amplification
by stimulated emission of radiation) was developed in 1962.
Emmett Leith and Juris Upatnieks, who were conducting radar research
at the University of Michigan, published the first laser holographs
in 1963. The laser was an intense light source with a very
long coherence length. Its monochromatic nature improved the resolution
of the images greatly. Also, there was no longer any restriction
on the size of the object to be photographed.
The availability of the laser allowed Leith and Upatnieks to propose
another improvement in holographic technique. Before 1964,
holograms were made of only thin transparent objects. A small region
of the hologram bore a one-to-one correspondence to a region
of the object. Only a small portion of the image could be viewed at
one time without the aid of additional optical components. Illuminating
the transparency diffusely allowed the whole image to be
seen at one time. This development also made it possible to record
holograms of diffusely reflected three-dimensional objects. Gabor
had seen from the beginning that this should make it possible to create
three-dimensional images.
After the early 1960’s, the field of holography developed very
quickly. Because holography is different from conventional photography,
the two techniques often complement each other. Gabor saw
his idea blossom into a very important technique in optical science.
Impact
Holography / 405
The development of the laser and the publication of the first laser
holograms in 1963 caused a blossoming of the new technique in
many fields. Soon, techniques were developed that allowed holograms
to be viewed with white light. It also became possible for holograms
to reconstruct multicolored images. Holographic methods
have been used to map terrain with radar waves and to conduct surveillance
in the fields of forestry, agriculture, and meteorology.

406 / Holography
By the 1990’s, holography had become a multimillion-dollar industry,
finding applications in advertising, as an art form, and in security
devices on credit cards, as well as in scientific fields. An alternate
form of holography, also suggested by Gabor, uses sound
waves. Acoustical imaging is useful whenever the medium around
the object to be viewed is opaque to light rays—for example, in
medical diagnosis. Holography has affected many areas of science,
technology, and culture.
See also Color film; Electron microscope; Infrared photography;
Laser; Mammography; Mass spectrograph; X-ray crystallography.
Further Reading
Greguss, Pál, Tung H. Jeong, and Dennis Gabor. Holography: Commemorating
the Ninetieth Anniversary of the Birth of Dennis Gabor.
Bellingham, Wash.: SPIE Optical Engineering Press, 1991.
Kasper, Joseph Emil, and Steven A. Feller. The Complete Book of Holograms:
How They Work and How to Make Them. Mineola, N.Y.: Dover,
2001.
McNair, Don. How to Make Holograms. Blue Ridge Summit, Pa.: Tab
Books, 1983.
Saxby, Graham. Holograms: How to Make and Display Them. New
York: Focal Press, 1980.

Hovercraft
Hovercraft
The invention: A vehicle requiring no surface contact for traction
that moves freely over a variety of surfaces—particularly
water—while supported on a self-generated cushion of air.
The people behind the invention:
Christopher Sydney Cockerell (1910- ), a British engineer
who built the first hovercraft
Ronald A. Shaw (1910- ), an early pioneer in aerodynamics
who experimented with hovercraft
Sir John Isaac Thornycroft (1843-1928), a Royal Navy architect
who was the first to experiment with air-cushion theory
Air-Cushion Travel
407
The air-cushion vehicle was first conceived by Sir John Isaac
Thornycroft of Great Britain in the 1870’s. He theorized that if a
ship had a plenum chamber (a box open at the bottom) for a hull
and it were pumped full of air, the ship would rise out of the water
and move faster, because there would be less drag. The main problem
was keeping the air from escaping from under the craft.
In the early 1950’s, Christopher Sydney Cockerell was experimenting
with ways to reduce both the wave-making and frictional
resistance that craft had to water. In 1953, he constructed a punt
with a fan that supplied air to the bottom of the craft, which could
thus glide over the surface with very little friction. The air was contained
under the craft by specially constructed side walls. In 1955,
the first true “hovercraft,” as Cockerell called it, was constructed of
balsa wood. It weighed only 127 grams and traveled over water at a
speed of 13 kilometers per hour.
On November 16, 1956, Cockerell successfully demonstrated
his model hovercraft at the patent agent’s office in London. It was
immediately placed on the “secret” list, and Saunders-Roe Ltd.
was given the first contract to build hovercraft in 1957. The first experimental
piloted hovercraft, the SR.N1, which had a weight of
3,400 kilograms and could carry three people at the speed of 25

408 / Hovercraft
knots, was completed on May 28, 1959, and publicly demonstrated
on June 11, 1959.
Ground Effect Phenomenon
In a hovercraft, a jet airstream is directed downward through a
hole in a metal disk, which forces the disk to rise. The jet of air has a
reverse effect of its own that forces the disk away from the surface.
Some of the air hitting the ground bounces back against the disk to
add further lift. This is called the “ground effect.” The ground effect
is such that the greater the under-surface area of the hovercraft, the
greater the reverse thrust of the air that bounces back. This makes
the hovercraft a mechanically efficient machine because it provides
three functions.
First, the ground effect reduces friction between the craft and the
earth’s surface. Second, it acts as a spring suspension to reduce
some of the vertical acceleration effects that arise from travel over
an uneven surface. Third, it provides a safe and comfortable ride at
high speed, whatever the operating environment. The air cushion
can distribute the weight of the hovercraft over almost its entire area
so that the cushion pressure is low.
The basic elements of the air-cushion vehicle are a hull, a propulsion
system, and a lift system. The hull, which accommodates the
crew, passengers, and freight, contains both the propulsion and lift
systems. The propulsion and lift systems can be driven by the same
power plant or by separate power plants. Early designs used only
one unit, but this proved to be a problem when adequate power was
not achieved for movement and lift. Better results are achieved
when two units are used, since far more power is used to lift the vehicle
than to propel it.
For lift, high-speed centrifugal fans are used to drive the air
through jets that are located under the craft. A redesigned aircraft
propeller is used for propulsion. Rudderlike fins and an air fan that
can be swiveled to provide direction are placed at the rear of the
craft.
Several different air systems can be used, depending on whether
a skirt system is used in the lift process. The plenum chamber system,
the peripheral jet system, and several types of recirculating air

Hovercraft / 409
systems have all been successfully tried without skirting. A variety
of rigid and flexible skirts have also proved to be satisfactory, depending
on the use of the vehicle.
Skirts are used to hold the air for lift. Skirts were once hung like cur-
Sir John Isaac Thornycroft
To be truly ahead of one’s time as an inventor, one must simply
know everything there is to know about a specialty and
then imagine something useful that contemporary technology
is not quite ready for.
John Isaac Thornycroft was such an inventor. Born in 1843 in
what were then the Papal States (Rome, Italy), he trained as an
engineer and became a naval architect. He opened a boatbuilding
and engineering company at Chiswick in London in
1866 and began looking for ways to improve the performance of
small seacraft. In 1877 he delivered the HMS Lightning, England’s
first torpedo boat, to the Royal Navy. He continued to
make torpedo boats for coastal waters, nicknamed “scooters,”
and made himself a leading expert on boat design. He introduced
stabilizers and modified hull and propeller shapes in order
to reduce drag from the hull’s contact with water and
thereby increase a boat’s speed.
One of his best ideas was to have the boat ride on a cushion
of air, so that air acted as a lubricant between the hull and water.
He even filed patents for the concept and built models, but the
power-source technology of the day was simply too inefficient.
Engines were too heavy for the amount of power they put out.
None could lift a full-size boat off the water and keep it on an air
cushion. So the hovercraft had to wait until the 1950’s and incorporation
of sophisticated internal combustion engines into
the design.
Meanwhile, Thornycroft and the company named after him
continued to make innovative transports and engines: a steampowered
van in 1896, a gas engine in 1902, and heavy trucks in
1912 that the British government used during World War I. By
the time Thornycroft died in 1928, on the Isle of Wight, he had
been knighted by a grateful government, which would benefit
from his company’s products and his advanced ideas for the
rest of the twentieth century.

410 / Hovercraft
tains around hovercraft. Instead of simple curtains to contain the air,
there are now complicated designs that contain the cushion, duct the
air, and even provide a secondary suspension. The materials used in
the skirting have also changed from a rubberized fabric to pure rubber
and nylon and, finally, to neoprene, a lamination of nylon and plastic.
The three basic types of hovercraft are the amphibious, nonamphibious,
and semiamphibious models. The amphibious type can
travel over water and land, whereas the nonamphibious type is restricted
to water travel. The semiamphibious model is also restricted
to water travel but may terminate travel by nosing up on a prepared
ramp or beach. All hovercraft contain built-in buoyancy tanks in the
side skirting as a safety measure in the event that a hovercraft must
settle on the water. Most hovercraft are equipped with gas turbines
and use either propellers or water-jet propulsion.
Impact
Hovercraft are used primarily for short passenger ferry services.
Great Britain was the only nation to produce a large number of hovercraft.
The British built larger and faster craft and pioneered their
successful use as ferries across the English Channel, where they
could reach speeds of 111 kilometers per hour (160 knots) and carry
more than four hundred passengers and almost one hundred vehicles.
France and the former Soviet Union have also effectively demonstrated
hovercraft river travel, and the Soviets have experimented
with military applications as well.
The military adaptations of hovercraft have been more diversified.
Beach landings have been performed effectively, and the United
States used hovercraft for river patrols during the Vietnam War.
Other uses also exist for hovercraft. They can be used as harbor pilot
vessels and for patrolling shores in a variety of police-and customs-related
duties. Hovercraft can also serve as flood-rescue craft
and fire-fighting vehicles. Even a hoverfreighter is being considered.
The air-cushion theory in transport systems is rapidly developing.
It has spread to trains and smaller people movers in many
countries. Their smooth, rapid, clean, and efficient operation makes
hovercraft attractive to transportation designers around the world.

See also Airplane; Atomic-powered ship; Bullet train; Gyrocompass.
Further Reading
Hovercraft / 411
Amyot, Joseph R. Hovercraft Technology, Economics, and Applications.
Amsterdam: Elsevier, 1989.
Croome, Angela. Hover Craft. 4th ed. London: Hodder and Stoughton,
1984.
Gromer, Cliff. “Flying Low.” Popular Mechanics 176, no. 9 (September,
1999).
McLeavy, Roy. Hovercraft and Hydrofoils. London: Jane’s Publishing,
1980.
Pengelley, Rupert. “Hovercraft Cushion the Blow of Amphibious
Operations.” Jane’s Navy International 104, no. 008 (October 1,
1999).
Robertson, Don. A Restless Spirit. New Port, Isle of Wight: Cross
Publishing, 1994.

412
Hydrogen bomb
Hydrogen bomb
The invention: Popularly known as the “H-Bomb,” the hydrogen
bomb differs from the original atomic bomb in using fusion,
rather than fission, to create a thermonuclear explosion almost a
thousand times more powerful.
The people behind the invention:
Edward Teller (1908- ), a Hungarian-born theoretical
physicist
Stanislaw Ulam (1909-1984), a Polish-born mathematician
Crash Development
A few months before the 1942 creation of the Manhattan Project,
the United States-led effort to build the atomic (fission) bomb, physicist
Enrico Fermi suggested to Edward Teller that such a bomb
could release more energy by the process of heating a mass of the
hydrogen isotope deuterium and igniting the fusion of hydrogen
into helium. Fusion is the process whereby two atoms come together
to form a larger atom, and this process usually occurs only in stars,
such as the Sun. Physicists Hans Bethe, George Gamow, and Teller
had been studying fusion since 1934 and knew of the tremendous
energy than could be released by this process—even more energy
than the fission (atom-splitting) process that would create the atomic
bomb. Initially, Teller dismissed Fermi’s idea, but later in 1942, in
collaboration with Emil Konopinski, he concluded that a hydrogen
bomb, or superbomb, could be made.
For practical considerations, it was decided that the design of the
superbomb would have to wait until after the war. In 1946, a secret
conference on the superbomb was held in Los Alamos, New Mexico,
that was attended by, among other Manhattan Project veterans,
Stanislaw Ulam and Klaus Emil Julius Fuchs. Supporting the investigation
of Teller’s concept, the conferees requested a more complete
mathematical analysis of his own admittedly crude calculations
on the dynamics of the fusion reaction. In 1947, Teller believed
that these calculations might take years. Two years later, however,

the Soviet explosion of an atomic bomb convinced Teller that America’s
Cold War adversary was hard at work on its own superbomb.
Even when new calculations cast further doubt on his designs,
Teller began a vigorous campaign for crash development of the hydrogen
bomb, or H-bomb.
The Superbomb
Hydrogen bomb / 413
Scientists knew that fusion reactions could be induced by the explosion
of an atomic bomb. The basic problem was simple and formidable:
How could fusion fuel be heated and compressed long
enough to achieve significant thermonuclear burning before the
atomic fission explosion blew the assembly apart? A major part of
the solution came from Ulam in 1951. He proposed using the energy
from an exploding atomic bomb to induce significant thermonuclear
reactions in adjacent fusion fuel components.
This arrangement, in which the A-bomb (the primary) is physically
separated from the H-bomb’s (the secondary’s) fusion fuel, became
known as the “Teller-Ulam configuration.” All H-bombs are
cylindrical, with an atomic device at one end and the other components
filling the remaining space. Energy from the exploding primary
could be transported by X rays and would therefore affect the
fusion fuel at near light speed—before the arrival of the explosion.
Frederick de Hoffman’s work verified and enriched the new concept.
In the revised method, moderated X rays from the primary irradiate
a reactive plastic medium surrounding concentric and generally
cylindrical layers of fusion and fission fuel in the secondary.
Instantly, the plastic becomes a hot plasma that compresses and
heats the inner layer of fusion fuel, which in turn compresses a central
core of fissile plutonium to supercriticality. Thus compressed,
and bombarded by fusion-produced, high-energy neutrons, the fission
element expands rapidly in a chain reaction from the inside
out, further compressing and heating the surrounding fusion fuel,
releasing more energy and more neutrons that induce fission in a
fuel casing-tamper made of normally stable uranium 238.
With its equipment to refrigerate the hydrogen isotopes, the device
created to test Teller’s new concept weighed more than sixty
tons. During Operation Ivy, it was tested at Elugelab in the Marshall

414 / Hydrogen bomb
Edward Teller
To call Edward Teller “controversial” is equivalent to saying
that the hydrogen bomb is “destructive”—an enormous understatement.
His forceful support for nuclear arms prompted
some to label him a war criminal while others consider him to
be one of the most thoughtful statesmen among scientists.
Teller was born into a Jewish family in Budapest, Hungary,
in 1908. He left his homeland to flee the anti-Semitic fascist government
of the late 1920’s and attended the University of Leipzig
in Germany. In 1930 he completed his doctorate and hoped
to settle into an academic career there, but he fled Germany
when Adolf Hitler came to power. Teller migrated to the United
States in 1935 and taught at George Washington University,
where with George Gamow he studied aspects of quantum mechanics
and nuclear physics. He became a U.S. citizen in 1941.
Teller was among the first physicists to realize the possibility
of an atomic (fission) bomb, and he became a central figure in
the Manhattan Project that built it during World War II. However,
he was already exploring the idea of a “superbomb” that
explodes because of a fusion reaction. He helped persuade
President Harry Truman to finance a project to build it and continued
to influence the politics of nuclear weapons and power
afterward. Teller developed the theoretical basis for the hydrogen
bomb and its rough design—and so is know as its father.
However, controversy later erupted over credit. Mathematician
Stanislaw Ulam claimed he contributed key insights and calculations,
a claim Teller vehemently denied. Teller, however, did
credit a young physicist, Richard L. Garwin, with creating the
successful working design for the first bomb.
Fiercely anticommunist, Teller argued for a strong nuclear
arsenal to make the Soviet Union afraid of attacking the United
States and supported space-based missile defense systems. He
served as director of the Lawrence Livermore National Laboratory,
professor at the University of California at Berkeley, and
senior fellow at the nearby Hoover Institution. In his nineties he
outraged environmentalists by suggesting that the atmosphere
could be manipulated with technology to offset the effects of
global warming.

Islands on November 1, 1952. Exceeding the expectations of all concerned
and vaporizing the island, the explosion equaled 10.4 million
tons of trinitrotoluene (TNT), which meant that it was about
seven hundred times more powerful than the atomic bomb dropped
on Hiroshima, Japan, in 1945. A version of this device weighing
about 20 tons was prepared for delivery by specially modified Air
Force B-36 bombers in the event of an emergency during wartime.
In development at Los Alamos before the 1952 test was a device
weighing only about 4 tons, a “dry bomb” that did not require refrigeration
equipment or liquid fusion fuel; when sufficiently compressed
and heated in its molded-powder form, the new fusion fuel
component, lithium-6 deutride, instantly produced tritium, an isotope
of hydrogen. This concept was tested during Operation Castle
at Bikini atoll in 1954 and produced a yield of 15 million tons of TNT,
the largest-ever nuclear explosion created by the United States.
Consequences
Hydrogen bomb / 415
Teller was not alone in believing that the world could produce
thermonuclear devices capable of causing great destruction. Months
before Fermi suggested to Teller the possibility of explosive thermonuclear
reactions on Earth, Japanese physicist Tokutaro Hagiwara
had proposed that a uranium 235 bomb could ignite significant fusion
reactions in hydrogen. The Soviet Union successfully tested an
H-bomb dropped from an airplane in 1955, one year before the
United States did so.
Teller became the scientific adviser on nuclear affairs of many
presidents, from Dwight D. Eisenhower to Ronald Reagan. The
widespread blast and fallout effects of H-bombs assured the mutual
destruction of the users of such weapons. During the Cold War
(from about 1947 to 1981), both the United States and the Soviet
Union possessed H-bombs. “Testing” these bombs made each side
aware of how powerful the other side was. Everyone wanted to
avoid nuclear war. It was thought that no one would try to start a
war that would end in the world’s destruction. This theory was
called deterrence: The United States wanted to let the Soviet Union
know that it had just as many bombs, or more, than it did, so that the
leaders of the Sovet Union would be deterred from starting a war.

416 / Hydrogen bomb
Teller knew that the availability of H-bombs on both sides was
not enough to guarantee that such weapons would never be used. It
was also necessary to make the Soviet Union aware of the existence
of the bombs through testing. He consistently advised against U.S.
participation with the Soviet Union in a moratorium (period of
waiting) on nuclear weapons testing. Largely based on Teller’s urging
that underground testing be continued, the United States rejected
a total moratorium in favor of the 1963 Atmospheric Test Ban
Treaty.
During the 1980’s, Teller, among others, convinced President
Reagan to embrace the Strategic Defense Initiative (SDI). Teller argued
that SDI components, such as the space-based “Excalibur,” a
nuclear bomb-powered X-ray laser weapon proposed by the Lawrence-Livermore
National Laboratory, would make thermonuclear
war not unimaginable, but theoretically impossible.
See also Airplane; Atomic bomb; Cruise missile; Rocket; Stealth
aircraft; V-2 rocket.
Further Reading
Blumberg, Stanley A., and Louis G. Panos. Edward Teller, Giant of the
Golden Age of Physics: A Biography. New York: Scribner’s, 1990.
Clash, James M. “Teller Tells It.” Forbes (May 17, 1999).
Teller, Edward, Wendy Teller, and Wilson Talley. Conversations on the
Dark Secrets of Physics. New York: Plenum Press, 1991.
York, Herbert E. The Advisors: Oppenheimer, Teller, and the Superbomb.
Stanford, Calif.: Stanford University Press, 1989.

IBM Model 1401 computer
IBM Model 1401 computer
The invention: A relatively small, simple, and inexpensive computer
that is often credited with having launched the personal
computer age.
The people behind the invention:
Howard H. Aiken (1900-1973), an American mathematician
Charles Babbage (1792-1871), an English mathematician and
inventor
Herman Hollerith (1860-1929), an American inventor
Computers: From the Beginning
417
Computers evolved into their modern form over a period of
thousands of years as a result of humanity’s efforts to simplify the
process of counting. Two counting devices that are considered to be
very simple, early computers are the abacus and the slide rule.
These calculating devices are representative of digital and analog
computers, respectively, because an abacus counts numbers of things,
while the slide rule calculates length measurements.
The first modern computer, which was planned by Charles Babbage
in 1833, was never built. It was intended to perform complex
calculations with a data processing/memory unit that was controlled
by punched cards. In 1944, Harvard University’s Howard H.
Aiken and the International Business Machines (IBM) Corporation
built such a computer—the huge, punched-tape-controlled Automatic
Sequence Controlled Calculator, or Mark I ASCC, which
could perform complex mathematical operations in seconds. During
the next fifteen years, computer advances produced digital computers
that used binary arithmetic for calculation, incorporated
simplified components that decreased the sizes of computers, had
much faster calculating speeds, and were transistorized.
Although practical computers had become much faster than
they had been only a few years earlier, they were still huge and extremely
expensive. In 1959, however, IBM introduced the Model
1401 computer. Smaller, simpler, and much cheaper than the multi-

418 / IBM Model 1401 computer
million-dollar computers that were available, the IBM Model 1401
computer was also relatively easy to program and use. Its low cost,
simplicity of operation, and very wide use have led many experts
to view the IBM Model 1401 computer as beginning the age of the
personal computer.
Computer Operation and IBM’s Model 1401
Modern computers are essentially very fast calculating machines
that are capable of sorting, comparing, analyzing, and outputting information,
as well as storing it for future use. Many sources credit
Aiken’s Mark I ASCC as being the first modern computer to be built.
This huge, five-ton machine used thousands of relays to perform complex
mathematical calculations in seconds. Soon after its introduction,
other companies produced computers that were faster and more versatile
than the Mark I. The computer development race was on.
All these early computers utilized the decimal system for calculations
until it was found that binary arithmetic, whose numbers are
combinations of the binary digits 1 and 0, was much more suitable
for the purpose. The advantage of the binary system is that the electronic
switches that make up a computer (tubes, transistors, or
chips) can be either on or off; in the binary system, the on state can
be represented by the digit 1, the off state by the digit 0. Strung together
correctly, binary numbers, or digits, can be inputted rapidly
and used for high-speed computations. In fact, the computer term
bit is a contraction of the phrase “binary digit.”
A computer consists of input and output devices, a storage device
(memory), arithmetic and logic units, and a control unit. In
most cases, a central processing unit (CPU) combines the logic,
arithmetic, memory, and control aspects. Instructions are loaded
into the memory via an input device, processed, and stored. Then,
the CPU issues commands to the other parts of the system to carry
out computations or other functions and output the data as needed.
Most output is printed as hard copy or displayed on cathode-ray
tube monitors, or screens.
The early modern computers—such as the Mark I ASCC—were
huge because their information circuits were large relays or tubes.
Computers became smaller and smaller as the tubes were replaced—

first with transistors, then with simple integrated circuits, and then
with silicon chips. Each technological changeover also produced
more powerful, more cost-effective computers.
In the 1950’s, with reliable transistors available, IBM began the
development of two types of computers that were completed by
about 1959. The larger version was the Stretch computer, which was
advertised as the most powerful computer of its day. Customized
for each individual purchaser (for example, the Atomic Energy
Commission), a Stretch computer cost $10 million or more. Some innovations
in Stretch computers included semiconductor circuits,
new switching systems that quickly converted various kinds of data
into one language that was understood by the CPU, rapid data readers,
and devices that seemed to anticipate future operations.
Consequences
IBM Model 1401 computer / 419
The IBM Model 1401 was the first computer sold in very large
numbers. It led IBM and other companies to seek to develop less expensive,
more versatile, smaller computers that would be sold to
small businesses and to individuals. Six years after the development
of the Model 1401, other IBM models—and those made by
other companies—became available that were more compact and
had larger memories. The search for compactness and versatility
continued. A major development was the invention of integrated
circuits by Jack S. Kilby of Texas Instruments; these integrated circuits
became available by the mid-1960’s. They were followed by
even smaller “microprocessors” (computer chips) that became available
in the 1970’s. Computers continued to become smaller and more
powerful.
Input and storage devices also decreased rapidly in size. At first,
the punched cards invented by Herman Hollerith, founder of the
Tabulation Machine Company (which later became IBM), were read
by bulky readers. In time, less bulky magnetic tapes and more compact
readers were developed, after which magnetic disks and compact
disc drives were introduced.
Many other advances have been made. Modern computers can
talk, create art and graphics, compose music, play games, and operate
robots. Further advancement is expected as societal needs

420 / IBM Model 1401 computer
change. Many experts believe that it was the sale of large numbers
of IBM Model 1401 computers that began the trend.
See also Apple II computer; BINAC computer; Colossus computer;
ENIAC computer; Personal computer; Supercomputer;
UNIVAC computer.
Further Reading
Carroll, Paul. Big Blues: The Unmaking of IBM. New York: Crown,
1993.
Chposky, James, and Ted Leonsis. Blue Magic: The People, Power, and
Politics Behind the IBM Personal Computer. New York: Facts on File,
1988.
Manes, Stephen, and Paul Andrews. Gates: How Microsoft’s Mogul
Reinvented an Industry. New York: Doubleday, 1993.

In vitro plant culture
In vitro plant culture
The invention: Method for propagating plants in artificial media
that has revolutionized agriculture.
The people behind the invention:
Georges Michel Morel (1916-1973), a French physiologist
Philip Cleaver White (1913- ), an American chemist
Plant Tissue Grows “In Glass”
In the mid-1800’s, biologists began pondering whether a cell isolated
from a multicellular organism could live separately if it were
provided with the proper environment. In 1902, with this question in
mind, the German plant physiologist Gottlieb Haberlandt attempted
to culture (grow) isolated plant cells under sterile conditions on an artificial
growth medium. Although his cultured cells never underwent
cell division under these “in vitro” (in glass) conditions, Haberlandt
is credited with originating the concept of cell culture.
Subsequently, scientists attempted to culture plant tissues and
organs rather than individual cells and tried to determine the medium
components necessary for the growth of plant tissue in vitro.
In 1934, Philip White grew the first organ culture, using tomato
roots. The discovery of plant hormones, which are compounds that
regulate growth and development, was crucial to the successful culture
of plant tissues; in 1939, Roger Gautheret, P. Nobécourt, and
White independently reported the successful culture of plant callus
tissue. “Callus” is an irregular mass of dividing cells that often results
from the wounding of plant tissue. Plant scientists were fascinated
by the perpetual growth of such tissue in culture and spent
years establishing optimal growth conditions and exploring the nutritional
and hormonal requirements of plant tissue.
Plants by the Millions
421
A lull in botanical research occurred during World War II, but
immediately afterward there was a resurgence of interest in applying
tissue culture techniques to plant research. Georges Morel, a

422 / In vitro plant culture
plant physiologist at the National Institute for Agronomic Research
in France, was one of many scientists during this time who
had become interested in the formation of tumors in plants as well
as in studying various pathogens such as fungi and viruses that
cause plant disease.
To further these studies, Morel adapted existing techniques in order
to grow tissue from a wider variety of plant types in culture, and
he continued to try to identify factors that affected the normal
growth and development of plants. Morel was successful in culturing
tissue from ferns and was the first to culture monocot plants.
Monocots have certain features that distinguish them from the other
classes of seed-bearing plants, especially with respect to seed structure.
More important, the monocots include the economically important
species of grasses (the major plants of range and pasture)
and cereals.
For these cultures, Morel utilized a small piece of the growing tip
of a plant shoot (the shoot apex) as the starting tissue material. This
tissue was placed in a glass tube, supplied with a medium containing
specific nutrients, vitamins, and plant hormones, and allowed
to grow in the light. Under these conditions, the apex tissue grew
roots and buds and eventually developed into a complete plant.
Morel was able to generate whole plants from pieces of the shoot
apex that were only 100 to 250 micrometers in length.
Morel also investigated the growth of parasites such as fungi and
viruses in dual culture with host-plant tissue. Using results from
these studies and culture techniques that he had mastered, Morel
and his colleague Claude Martin regenerated virus-free plants from
tissue that had been taken from virally infected plants. Tissues from
certain tropical species, dahlias, and potato plants were used for the
original experiments, but after Morel adapted the methods for the
generation of virus-free orchids, plants that had previously been
difficult to propagate by any means, the true significance of his
work was recognized.
Morel was the first to recognize the potential of the in vitro culture
methods for the mass propagation of plants. He estimated that several
million plants could be obtained in one year from a single small
piece of shoot-apex tissue. Plants generated in this manner were
clonal (genetically identical organisms prepared from a single plant).

With other methods of plant propagation, there is often a great variation
in the traits of the plants produced, but as a result of Morel’s
ideas, breeders could select for some desirable trait in a particular
plant and then produce multiple clonal plants, all of which expressed
the desired trait. The methodology also allowed for the production of
virus-free plant material, which minimized both the spread of potential
pathogens during shipping and losses caused by disease.
Consequences
In vitro plant culture / 423
In vitro plant culture has been especially useful for species such as palm trees that cannot be
propagated by other methods, such as by sowing seeds or grafting. (PhotoDisc)
Variations on Morel’s methods are used to propagate plants used
for human food consumption; plants that are sources of fiber, oil,
and livestock feed; forest trees; and plants used in landscaping and
in the floral industry. In vitro stocks are preserved under deepfreeze
conditions, and disease-free plants can be proliferated quickly
at any time of the year after shipping or storage.
The in vitro multiplication of plants has been especially useful
for species such as coconut and certain palms that cannot be propagated
by other methods, such as by sowing seeds or grafting, and
has also become important in the preservation and propagation of

424 / In vitro plant culture
rare plant species that might otherwise have become extinct. Many
of these plants are sources of pharmaceuticals, oils, fragrances, and
other valuable products.
The capability of regenerating plants from tissue culture has also
been crucial in basic scientific research. Plant cells grown in culture
can be studied more easily than can intact plants, and scientists have
gained an in-depth understanding of plant physiology and biochemistry
by using this method. This information and the methods
of Morel and others have made possible the genetic engineering and
propagation of crop plants that are resistant to disease or disastrous
environmental conditions such as drought and freezing. In vitro
techniques have truly revolutionized agriculture.
See also Artificial insemination; Cloning; Genetically engineered
insulin; Rice and wheat strains.
Further Reading
Arbury, Jim, Richard Bird, Mike Honour, Clive Innes, and Mike Salmon.
The Complete Book of Plant Propagation. Newtown, Conn.:
Taunton Press, 1997.
Clarke, Graham. The Complete Book of Plant Propagation. London:
Seven Dials, 2001.
Hartmann, Hudson T. Plant Propagation: Principles and Practices. 6th
ed. London: Prentice-Hall, 1997.
Heuser, Charles. The Complete Book of Plant Propagation. Newtown,
Conn.: Taunton Press, 1997.

Infrared photography
Infrared photography
The invention: The first application of color to infrared photography,
which performs tasks not possible for ordinary photography.
The person behind the invention:
Sir William Herschel (1738-1822), a pioneering English
astronomer
Invisible Light
425
Photography developed rapidly in the nineteenth century when it
became possible to record the colors and shades of visible light on
sensitive materials. Visible light is a form of radiation that consists of
electromagnetic waves, which also make up other forms of radiation
such as X rays and radio waves. Visible light occupies the range of
wavelengths from about 400 nanometers (1 nanometer is 1 billionth
of a meter) to about 700 nanometers in the electromagnetic spectrum.
Infrared radiation occupies the range from about 700 nanometers
to about 1,350 nanometers in the electromagnetic spectrum. Infrared
rays cannot be seen by the human eye, but they behave in the
same way that rays of visible light behave; they can be reflected, diffracted
(broken), and refracted (bent).
Sir William Herschel, a British astronomer, discovered infrared
rays in 1800 by calculating the temperature of the heat that they produced.
The term “infrared,” which was probably first used in 1800,
was used to indicate rays that had wavelengths that were longer than
those on the red end (the high end) of the spectrum of visible light but
shorter than those of the microwaves, which appear higher on the
electromagnetic spectrum. Infrared film is therefore sensitive to the
infrared radiation that the human eye cannot see or record. Dyes that
were sensitive to infrared radiation were discovered early in the
twentieth century, but they were not widely used until the 1930’s. Because
these dyes produced only black-and-white images, their usefulness
to artists and researchers was limited. After 1930, however, a
tidal wave of infrared photographic applications appeared.

426 / Infrared photography
The Development of Color-Sensitive Infrared Film
In the early 1940’s, military intelligence used infrared viewers for
night operations and for gathering information about the enemy. One
device that was commonly used for such purposes was called a
“snooper scope.” Aerial photography with black-and-white infrared
film was used to locate enemy hiding places and equipment. The images
that were produced, however, often lacked clear definition.
The development in 1942 of the first color-sensitive infrared film,
Ektachrome Aero Film, became possible when researchers at the
Eastman Kodak Company’s laboratories solved some complex chemical
and physical problems that had hampered the development of
color infrared film up to that point. Regular color film is sensitive to
all visible colors of the spectrum; infrared color film is sensitive to
violet, blue, and red light as well as to infrared radiation. Typical
color film has three layers of emulsion, which are sensitized to blue,
green, and red. Infrared color film, however, has its three emulsion
layers sensitized to green, red, and infrared. Infrared wavelengths
are recorded as reds of varying densities, depending on the intensity
of the infrared radiation. The more infrared radiation there is,
the darker the color of the red that is recorded.
In infrared photography, a filter is placed over the camera lens to
block the unwanted rays of visible light. The filter blocks visible and
ultraviolet rays but allows infrared radiation to pass. All three layers
of infrared film are sensitive to blue, so a yellow filter is used. All
blue radiation is absorbed by this filter.
In regular photography, color film consists of three basic layers:
the top layer is sensitive to blue light, the middle layer is sensitive to
green, and the third layer is sensitive to red. Exposing the film to
light causes a latent image to be formed in the silver halide crystals
that make up each of the three layers. In infrared photography, color
film consists of a top layer that is sensitive to infrared radiation, a
middle layer sensitive to green, and a bottom layer sensitive to red.
“Reversal processing” produces blue in the infrared-sensitive layer,
yellow in the green-sensitive layer, and magenta in the red-sensitive
layer. The blue, yellow, and magenta layers of the film produce the
“false colors” that accentuate the various levels of infrared radiation
shown as red in a color transparency, slide, or print.

Sir William Herschel
Infrared photography / 427
During his long career Sir William Herschel passed from human
music to the music of the spheres, and in doing so revealed
the invisible unlike any astronomer before him.
He was born Friedrich Wilhelm Herschel in Hannover, Germany,
in 1738. Like his brothers, he trained to be a musician in a
local regimental band. In 1757 he had to flee to England
because his regiment was on the losing side of a
war. Settling in the town of Bath, he supported himself
with music, eventually becoming the organist for
the city’s celebrated Octagon Chapel. He studied the
music theory in Robert Smith’s book on harmonics
and, discovering another book by Smith about optics
and astronomy, read that too. He was immediately
hooked. By 1773 he was assembling his own telescopes,
and within ten years he had built the most powerful instruments
in the land. He interested King George III in astronomy
and was rewarded with a royal pension that gave him the
leisure to survey the heavens.
Herschel looked deeper into space than anyone before him.
He discovered thousands of double stars and nebulae that had
been invisible to astronomers with less powerful telescopes
than his. He was the first person in recorded history to discover
a planet—Uranus. While trying to learn the construction of the
sun, he conducted hundreds of experiments with light. He
found, unexpectedly, that he could feel heat from the sun even
when visible light was filtered out, and concluded that some solar
radiation—in this case infrared—was invisible to human
eyes.
Late in his career Herschel addressed the grandest of all invisible
aspects of the nature: the structure of the universe. His
investigations led him to conclude that the nebulae he had so
often observed were in themselves vast clouds of stars, very far
away—they were galaxies. It was a key conceptual step in the
development of modern cosmology.
By the time Herschel died in 1822, he had trained his sister
Caroline and his son John to carry on his work. Both became celebrated
astronomers in their own right.
(Library of Congess)

428 / Infrared photography
The color of the dye that is formed in a particular layer bears no
relationship to the color of light to which the layer is sensitive. If the
relationship is not complementary, the resulting colors will be false.
This means that objects whose colors appear to be similar to the
human eye will not necessarily be recorded as similar colors on infrared
film. A red rose with healthy green leaves will appear on infrared
color film as being yellow with red leaves, because the chlorophyll
contained in the plant leaf reflects infrared radiation and
causes the green leaves to be recorded as red. Infrared radiation
from about 700 nanometers to about 900 nanometers on the electromagnetic
spectrum can be recorded by infrared color film. Above
900 nanometers, infrared radiation exists as heat patterns that must
be recorded by nonphotographic means.
Impact
Infrared photography has proved to be valuable in many of the
sciences and the arts. It has been used to create artistic images that
are often unexpected visual explosions of everyday views. Because
infrared radiation penetrates haze easily, infrared films are often
used in mapping areas or determining vegetation types. Many
cloud-covered tropical areas would be impossible to map without
infrared photography. False-color infrared film can differentiate between
healthy and unhealthy plants, so it is widely used to study insect
and disease problems in plants. Medical research uses infrared
photography to trace blood flow, detect and monitor tumor growth,
and to study many other physiological functions that are invisible
to the human eye.
Some forms of cancer can be detected by infrared analysis before
any other tests are able to perceive them. Infrared film is used in
criminology to photograph illegal activities in the dark and to study
evidence at crime scenes. Powder burns around a bullet hole, which
are often invisible to the eye, show clearly on infrared film. In addition,
forgeries in documents and works of art can often be seen
clearly when photographed on infrared film. Archaeologists have
used infrared film to locate ancient sites that are invisible in daylight.
Wildlife biologists also document the behavior of animals at
night with infrared equipment.

See also Autochrome plate; Color film; Fax machine; Instant
photography.
Further Reading
Infrared photography / 429
Collins, Douglas. The Story of Kodak. New York: Harry N. Abrams,
1990.
Cummins, Richard. “Infrared Revisited.” Petersen’s Photographic
Magazine 23 (February, 1995).
Paduano, Joseph. The Art of Infrared Photography. 4th ed. Buffalo,
N.Y: Amherst Media, 1998.
Richards, Dan. “The Strange Otherworld of Infrared.” Popular Photography
62, no. 6 (June, 1998).
White, Laurie. Infrared Photography Handbook. Amherst, N.Y.: Amherst
Media, 1995.

430
Instant photography
Instant photography
The invention: Popularly known by its Polaroid tradename, a camera
capable of producing finished photographs immediately after
its film was exposed.
The people behind the invention:
Edwin Herbert Land (1909-1991), an American physicist and
chemist
Howard G. Rogers (1915- ), a senior researcher at Polaroid
and Land’s collaborator
William J. McCune (1915- ), an engineer and head of the
Polaroid team
Ansel Adams (1902-1984), an American photographer and
Land’s technical consultant
The Daughter of Invention
Because he was a chemist and physicist interested primarily in
research relating to light and vision, and to the materials that affect
them, it was inevitable that Edwin Herbert Land should be drawn
into the field of photography. Land founded the Polaroid Corporation
in 1929. During the summer of 1943, while Land and his wife
were vacationing in Santa Fe, New Mexico, with their three-yearold
daughter, Land stopped to take a picture of the child. After the
picture was taken, his daughter asked to see it. When she was told
she could not see the picture immediately, she asked how long it
would be. Within an hour after his daughter’s question, Land had
conceived a preliminary plan for designing the camera, the film,
and the physical chemistry of what would become the instant camera.
Such a device would, he hoped, produce a picture immediately
after exposure.
Within six months, Land had solved most of the essential problems
of the instant photography system. He and a small group of associates
at Polaroid secretly worked on the project. Howard G. Rogers
was Land’s collaborator in the laboratory. Land conferred the
responsibility for the engineering and mechanical phase of the project
on William J. McCune, who led the team that eventually de-

signed the original camera and the machinery that produced both
the camera and Land’s new film.
The first Polaroid Land camera—the Model 95—produced photographs
measuring 8.25 by 10.8 centimeters; there were eight pictures
to a roll. Rather than being black-and-white, the original Polaroid
prints were sepia-toned (producing a warm, reddish-brown color).
The reasons for the sepia coloration were chemical rather than aesthetic;
as soon as Land’s researchers could devise a workable formula
for sharp black-and-white prints (about ten months after the camera
was introduced commercially), they replaced the sepia film.
A Sophisticated Chemical Reaction
Instant photography / 431
Although the mechanical process involved in the first demonstration
camera was relatively simple, this process was merely
the means by which a highly sophisticated chemical reaction—
the diffusion transfer process—was produced.
In the basic diffusion transfer process, when an exposed negative
image is developed, the undeveloped portion corresponds
to the opposite aspect of the image, the positive. Almost all selfprocessing
instant photography materials operate according to
three phases—negative development, diffusion transfer, and
positive development. These occur simultaneously, so that positive
image formation begins instantly. With black-and-white materials,
the positive was originally completed in about sixty seconds; with
color materials (introduced later), the process took somewhat longer.
The basic phenomenon of silver in solution diffusing from one
emulsion to another was first observed in the 1850’s, but no practical
use of this action was made until 1939. The photographic use of
diffusion transfer for producing normal-continuous-tone images
was investigated actively from the early 1940’s by Land and his associates.
The instant camera using this method was demonstrated
in 1947 and marketed in 1948.
The fundamentals of photographic diffusion transfer are simplest
in a black-and-white peel-apart film. The negative sheet is exposed
in the camera in the normal way. It is then pulled out of the
camera, or film pack holder, by a paper tab. Next, it passes through a
set of rollers, which press it face-to-face with a sheet of receiving ma-

432 / Instant photography
Edwin H. Land
Born in Bridgeport, Connecticut in 1909, Edwin Herbert
Land developed an obsession with color vision. As a boy, he
slept with a copy of an optics textbook under his pillow. When
he went to Harvard to study physics, he found the instruction
too elementary and spent much of the time educating himself at
the New York Public Library. While there, he thought of the first
of his many sight-related inventions.
He realized that by lining up tiny crystals and embedding
them in clear plastic he could make a large, inexpensive light polarizer.
He patented the idea for this “Polaroid” lens in 1929 (the
first of more than five hundred patents) and in 1932 set up a commercial
laboratory with his Harvard physics professor, George
Wheelwright III. Five years later he opened the Polaroid Corporation
in Boston to exploit the commercial potential of the lenses.
They were to be used most famously as sunglasses, camera filters,
eyeglasses for producing three-dimensional effects in movies,
and glare-reduction screens for visual display terminals.
In 1937, with Joseph Mallory, Land invented the vectograph—
a device that superimposed two photographs in order to create
a three-dimensional image. The invention dramatically improved
the aerial photography during World War II and the Cold War.
In fact, Land had a hand in designing both the camera carried
aboard Lockheed’s U2 spyplane and the plane itself.
While not busy running the Polaroid Corporation and overseeing
development of its cameras, Land pursued his passion for
experimenting with color and developed a widely respected theory
of color vision. When he retired in 1982, he launched the
Rowland Institute for Science in Boston, once described as a cross
between a private laboratory and a private art gallery. (Land had
a deep interest in modern art.) He and other scientists there conducted
research on artificial intelligence, genetics, microscopy,
holography, protein dynamics, and color vision. Land died in
1991 in Cambridge, Massachusetts, but the institute carries forward
his legacy of scientific curiosity and practical application.
terial included in the film pack. Simultaneously, the rollers rupture
a pod of reagent chemicals that are spread evenly by the rollers
between the two layers. The reagent contains a strong alkali and a
silver halide solvent, both of which diffuse into the negative emul-

sion. There the alkali activates the developing agent, which immediately
reduces the exposed halides to a negative image. At the
same time, the solvent dissolves the unexposed halides. The silver
in the dissolved halides forms the positive image.
Impact
The Polaroid Land camera had a tremendous impact on the photographic
industry as well as on the amateur and professional photographer.
Ansel Adams, who was known for his monumental,
ultrasharp black-and-white panoramas of the American West, suggested
to Land ways in which the tonal value of Polaroid film could
be enhanced, as well as new applications for Polaroid photographic
technology.
Soon after it was introduced, Polaroid photography became part
of the American way of life and changed the face of amateur photography
forever. By the 1950’s, Americans had become accustomed
to the world of recorded visual information through films, magazines,
and newspapers; they also had become enthusiastic picturetakers
as a result of the growing trend for simpler and more convenient
cameras. By allowing these photographers not only to record
their perceptions but also to see the results almost immediately, Polaroid
brought people closer to the creative process.
See also Autochrome plate; Brownie camera; Color film; Fax machine;
Xerography.
Further Reading
Instant photography / 433
Adams, Ansel. Polaroid Land Photography Manual. New York: Morgan
& Morgan, 1963.
Innovation/Imagination: Fifty Years of Polaroid Photography. New York:
H. N. Abrams in association with the Friends of Photography,
1999.
McElheny, Victor K. Insisting on the Impossible: The Life of Edwin Land.
Cambridge, Mass.: Perseus Books, 1998.
Olshaker, Mark. The Instant Image. New York: Stein & Day, 1978.
Wensberg, Peter C. Land’s Polaroid. Boston: Houghton Mifflin, 1987.

434
Interchangeable parts
Interchangeable parts
The invention: A key idea in the late Industrial Revolution, the
interchangeability of parts made possible mass production of
identical products.
The people behind the invention:
Henry M. Leland (1843-1932), president of Cadillac Motor Car
Company in 1908, known as a master of precision
Frederick Bennett, the British agent for Cadillac Motor Car
Company who convinced the Royal Automobile Club to run
the standardization test at Brooklands, England
Henry Ford (1863-1947), founder of Ford Motor Company who
introduced the moving assembly line into the automobile
industry in 1913
An American Idea
Mass production is a twentieth century methodology that for the
most part is a result of nineteenth century ideas. It is a phenomenon
that, although its origins were mostly American, has consequently
changed the entire world. The use of interchangeable parts, the feasibility
of which was demonstrated by the Cadillac Motor Car Company
in 1908, was instrumental in making mass production possible.
The British phase of the Industrial Revolution saw the application
of division of labor, the first principle of industrialization, to capitalistdirected
manufacturing processes. Centralized power sources were
connected through shafts, pulleys, and belts to machines housed in
factories. Even after these dramatic changes, the British preferred to
produce unique, handcrafted products formed one step at a time using
general-purpose machine tools. Seldom did they make separate components
to be assembled into standardized products.
Stories about American products that were assembled from fully
interchangeable parts began to reach Great Britain. In 1851, the British
public saw a few of these products on display at an exhibition in
London’s Crystal Palace. In 1854, they were informed by one of their
own investigative commissions that American manufacturers were

uilding military weapons and a number of consumer products
with separately made parts that could be easily assembled, with little
filing and fitting, by semiskilled workers.
English industrialists had probably heard as much as they ever
wanted to about this so-called “American system of manufacturing”
by the first decade of the twentieth century, when word came
that American companies were building automobiles with parts
manufactured so precisely that they were interchangeable.
The Cadillac
Interchangeable parts / 435
During the fall of 1907, Frederick Bennett, an Englishman who
served as the British agent for the Cadillac Motor Car Company, paid
a visit to the company’s Detroit, Michigan, factory and was amazed
at what he saw. He later described the assembling of the relatively inexpensive
Cadillac vehicles as a demonstration of the beauty and
practicality of precision. He was convinced that if his countrymen
could see what he had seen they would also be impressed.
Most automobile builders at the time claimed that their vehicles
were built with handcrafted quality, yet at the same time they advertised
that they could supply repair parts that would fit perfectly.
In actuality, machining and filing were almost always required
when parts were replaced, and only shops with proper equipment
could do the job.
Upon his return to London, Bennett convinced the Royal Automobile
Club to sponsor a test of the precision of automobile parts. A
standardization test was set to begin on February 29, 1908, and all of
the companies then selling automobiles were invited to participate.
Only the company that Bennett represented, Cadillac, was willing
to enter the contest.
Three one-cylinder Cadillacs, each painted a different color, were
taken from stock at the company’s warehouse in London to a garage
near the Brooklands race track. The cars were first driven around
the track ten times to prove that they were operable. British mechanics
then dismantled the vehicles, placing their parts in piles in the
center of the garage, making sure that there was no way of identifying
from which car each internal piece came. Then, as a further test,
eighty-nine randomly selected parts were removed from the piles

436 / Interchangeable parts
and replaced with new ones straight from Cadillac’s storeroom in
London. The mechanics then proceeded to reassemble the automobiles,
using only screwdrivers and wrenches.
After the reconstruction, which took two weeks, the cars were
driven from the garage. They were a motley looking trio, with fenders,
doors, hoods, and wheels of mixed colors. All three were then
driven five hundred miles around the Brooklands track. The British
were amazed. Cadillac was awarded the club’s prestigious Dewar
Trophy, considered in the young automobile industry to be almost
the equivalent of a Nobel Prize. A number of European and American
automobile manufacturers began to consider the promise of interchangeable
parts and the assembly line system.
Henry M. Leland
Cadillac’s precision-built automobiles were the result of a lifetime
of experience of Henry M. Leland, an American engineer.
Known in Detroit at the turn of the century as a master of precision,
Leland became the primary connection between a series of nineteenth
century attempts to make interchangeable parts and the
large-scale use of precision parts in mass production manufacturing
during the twentieth century.
The first American use of truly interchangeable parts had occurred
in the military, nearly three-quarters of a century before the
test at Brooklands. Thomas Jefferson had written from France about
a demonstration of uniform parts for musket locks in 1785. A few
years later, Eli Whitney attempted to make muskets for the American
military by producing separate parts for assembly using specialized
machines. He was never able to produce the precision necessary
for truly interchangeable parts, but he promoted the idea
intensely. It was in 1822 at the Harpers Ferry Armory in Virginia,
and then a few years later at the Springfield Armory in Massachusetts,
that the necessary accuracy in machining was finally achieved
on a relatively large scale.
Leland began his career at the Springfield Armory in 1863, at the
age of nineteen. He worked as a tool builder during the Civil War
years and soon became an advocate of precision manufacturing. In
1890, Leland moved to Detroit, where he began a firm, Leland &

Henry Martyn Leland
Interchangeable parts / 437
Henry Martyn Leland (1843-1932) is the unsung giant of
early automobile manufacturers, launching two of the bestknown
American car companies, Cadillac and Lincoln, and influenced
the success of General Motors, as well as introducing
the use of interchangeable parts. Had he allowed a model to be
named after him, as did Henry Ford and Ransom Olds, he
might have become a household name too, but he refused any
such suggestion.
Leland worked in factories during his youth. During the
Civil War he honed his skills as a machinist at the U.S. Armory
in Springfield, Massachusetts, helping build rifles with interchangeable
parts. After the war, he learned how to machine
parts to within one-thousandth of an inch, fabricated the first
mechanical barber’s clippers, and refined the workings of air
brakes for locomotives.
This was all warm-up. In 1890 he moved to Detroit and
opened his own business, Leland and Faulconer Manufacturing
Company, specializing in automobile engines. The 10.25-horsepower
engine he built for Olds in 1901 was rejected, but the single-cylinder
(“one-lunger”) design that powered the first Cadillacs
set him on the high road in the automotive industry. More
innovations followed. He developed the electric starter, electric
lights, and dimmable headlights. During World War I he built
airplane engines for the U.S. government, and afterward converted
the design for use in his new creation, the Lincoln.
Throughout, he demanded precision from himself and those
working for him. Once, for example, he complained to Alfred P.
Sloan that a lot of ball bearings that Sloan had sold him varied
from the required engineering tolerances and showed Sloan a
few misshapen bearings to prove the claim. “Even though you
make thousands,” Leland admonished Sloan, “the first and last
should be precisely the same.” Sloan took the lesson very seriously.
When he later led General Motors to the top of the industry,
he credited Leland with teaching him what mass production
was all about.
Faulconer, that would become internationally known for precision
machining. His company did well supplying parts to the bicycle industry
and internal combustion engines and transmissions to early

438 / Interchangeable parts
automobile makers. In 1899, Leland & Faulconer became the primary
supplier of engines to the first of the major automobile producers,
the Olds Motor Works.
In 1902, the directors of another Detroit firm, the Henry Ford
Company, found themselves in a desperate situation. Henry Ford,
the company founder and chief engineer, had resigned after a disagreement
with the firm’s key owner, William Murphy. Leland was
asked to take over the reorganization of the company. Because it
could no longer use Ford’s name, the business was renamed in
memory of the French explorer who had founded Detroit two hundred
years earlier, Antoine de la Mothe Cadillac.
Leland was appointed president of the Cadillac Motor Car Company.
The company, under his influence, soon became known for its
precision manufacturing. He disciplined its suppliers, rejecting anything
that did not meet his specifications, and insisted on precision
machining for all parts. By 1906, Cadillac was outselling all of its
competitors, including Oldsmobile and Ford’s new venture, the
Ford Motor Company. After the Brooklands demonstration in 1908,
Cadillac became recognized worldwide for quality and interchangeability
at a reasonable price.
Impact
The Brooklands demonstration went a long way in proving that
mass-produced goods could be durable and of relatively high quality.
It showed that standardized products, although often less costly
to make, were not necessarily cheap substitutes for handcrafted and
painstakingly fitted products. It also demonstrated that, through
the use of interchangeable parts, the job of repairing such complex
machines as automobiles could be made comparatively simple,
moving maintenance and repair work from the well-equipped machine
shop to the neighborhood garage or even to the home.
Because of the international publicity Cadillac received, Leland’s
methods began to be emulated by others in the automobile industry.
His precision manufacturing, as his daughter-in-law would later
write in his biography, “laid the foundation for the future American
[automobile] industry.” The successes of automobile manufacturers
quickly led to the introduction of mass production methods, and

strategies designed to promote their necessary corollary mass consumption,
in many other American businesses.
In 1909, Cadillac was acquired by William Crapo Durant as the
flagship company of his new holding company, which he labeled
General Motors. Leland continued to improve his production methods,
while also influencing his colleagues in the other General Motors
companies to implement many of his techniques. By the mid-
1920’s, General Motors had become the world’s largest manufacturer
of automobiles. Much of its success resulted from extensions
of Leland’s ideas. The company began offering a number of brand
name vehicles in a variety of price ranges for marketing purposes,
while still keeping the costs of production down by including in
each design a large number of commonly used, highly standardized
components.
Henry Leland resigned from Cadillac during World War I after
trying to convince Durant that General Motors should play an important
part in the war effort by contracting to build Liberty aircraft
engines for the military. He formed his own firm, named after his favorite
president, Abraham Lincoln, and went on to build about four
thousand aircraft engines in 1917 and 1918. In 1919, ready to make
automobiles again, Leland converted the Lincoln Motor Company
into a car manufacturer. Again he influenced the industry by setting
high standards for precision, but in 1921 an economic recession
forced his new venture into receivership. Ironically, Lincoln was
purchased at auction by Henry Ford. Leland retired, his name overshadowed
by those of individuals to whom he had taught the importance
of precision and interchangeable parts. Ford, as one example,
went on to become one of America’s industrial legends by
applying the standardized parts concept.
Ford and the Assembly Line
Interchangeable parts / 439
In 1913, Henry Ford, relying on the ease of fit made possible
through the use of machined and stamped interchangeable parts,
introduced the moving assembly line to the automobile industry.
He had begun production of the Model T in 1908 using stationary
assembly methods, bringing parts to assemblers. After having learned
how to increase component production significantly, through experi-

440 / Interchangeable parts
ments with interchangeable parts and moving assembly methods in
the magneto department, he began to apply this same concept to final
assembly. In the spring of 1913, Ford workers began dragging car
frames past stockpiles of parts for assembly. Soon a power source
was attached to the cars through a chain drive, and the vehicles
were pulled past the stockpiles at a constant rate.
From this time on, the pace of tasks performed by assemblers
would be controlled by the rhythm of the moving line. As demand
for the Model T increased, the number of employees along the line
was increased and the jobs were broken into smaller and simpler
tasks. With stationary assembly methods, the time required to assemble
a Model T had averaged twelve and one-half person-hours.
Dragging the chassis to the parts cut the time to six hours per vehicle,
and the power-driven, constant-rate line produced a Model T
with only ninety-three minutes of labor time. Because of these
amazing increases in productivity, Ford was able to lower the selling
price of the basic model from $900 in 1910 to $260 in 1925. He
had revolutionized automobile manufacturing: The average family
could now afford an automobile.
Soon the average family would also be able to afford many of the
other new products they had seen in magazines and newspapers.
At the turn of the century, there were many new household appliances,
farm machines, ready-made fashions, and prepackaged food
products on the market, but only the wealthier class could afford
most of these items. Major consumer goods retailers such as Sears,
Roebuck and Company, Montgomery Ward, and the Great Atlantic
and Pacific Tea Company were anxious to find lower-priced versions
of these products to sell to a growing middle-class constituency.
The methods of mass production that Henry Ford had popularized
seemed to carry promise for these products as well. During
the 1920’s, by working with such key manufacturers as Whirlpool,
Hoover, General Electric, and Westinghouse, these large distributors
helped introduce mass production methods into a large number
of consumer product industries. They changed class markets
into mass markets.
The movement toward precision also led to the birth of a separate
industry based on the manufacture of machine tools. A general
purpose lathe, milling machine, or grinder could be used for a num-

er of operations, but mass production industries called for narrowpurpose
machines designed for high-speed use in performing one
specialized step in the production process. Many more machines
were now required, one at each step in the production process. Each
machine had to be simpler to operate, with more automatic features,
because of an increased dependence on unskilled workers. The machine
tool industry became the foundation of modern production.
The miracle of mass production that followed, in products as
diverse as airplanes, communication systems, and hamburgers,
would not have been possible without the precision insisted upon
by Henry Leland in the first decade of the twentieth century. It
would not have come about without the lessons learned by Henry
Ford in the use of specialized machines and assembly methods, and
it would not have occurred without the growth of the machine tool
industry. Cadillac’s demonstration at Brooklands in 1908 proved
the practicality of precision manufacturing and interchangeable
parts to the world. It inspired American manufacturers to continue
to develop these ideas; it convinced Europeans that such production
was possible; and, for better or for worse, it played a major part
in changing the world.
See also CAD/CAM; Assembly line; Internal combustion engine.
Further Reading
Interchangeable parts / 441
Hill, Frank Ernest. The Automobile: How It Came, Grew, and Has
Changed Our Lives. New York: Dodd, Mead, 1967.
Hounshell, David A. From the American System to Mass Production,
1800-1932. Baltimore: Johns Hopkins University Press, 1984.
Leland, Ottilie M., and Minnie Dubbs Millbrook. Master of Precision:
Henry M. Leland. 1966. Reprint. Detroit: Wayne State University
Press, 1996.
Marcus, Alan I., and Howard P. Segal. Technology in America: A Brief
History. Fort Worth, Texas: Harcourt Brace College, 1999.
Nevins, Allan, and Frank Ernest Hill. The Times, the Man, the Company.
Vol. 1 in Ford. New York: Charles Scribner’s Sons, 1954.

442
Internal combustion engine
Internal combustion engine
The invention: The most common type of engine in automobiles
and many other vehicles, the internal combusion engine is characterized
by the fact that it burns its liquid fuelly internally—in
contrast to engines, such as the steam engine, that burn fuel in external
furnaces.
The people behind the invention:
Sir Harry Ralph Ricardo (1885-1974), an English engineer
Oliver Thornycroft (1885-1956), an engineer and works manager
Sir David Randall Pye (1886-1960), an engineer and
administrator
Sir Robert Waley Cohen (1877-1952), a scientist and industrialist
The Internal Combustion Engine: 1900-1916
By the beginning of the twentieth century, internal combustion
engines were almost everywhere. City streets in Berlin, London,
and New York were filled with automobile and truck traffic; gasoline-
and diesel-powered boat engines were replacing sails; stationary
steam engines for electrical generation were being edged out by
internal combustion engines. Even aircraft use was at hand: To
progress from the Wright brothers’ first manned flight in 1903 to the
fighting planes of World War I took only a little more than a decade.
The internal combustion engines of the time, however, were
primitive in design. They were heavy (10 to 15 pounds per output
horsepower, as opposed to 1 to 2 pounds today), slow (typically
1,000 or fewer revolutions per minute or less, as opposed to 2,000 to
5,000 today), and extremely inefficient in extracting the energy content
of their fuel. These were not major drawbacks for stationary applications,
or even for road traffic that rarely went faster than 30 or
40 miles per hour, but the advent of military aircraft and tanks demanded
that engines be made more efficient.

Engine and Fuel Design
Internal combustion engine / 443
Harry Ricardo, son of an architect and grandson (on his mother’s
side) of an engineer, was a central figure in the necessary redesign of
internal combustion engines. As a schoolboy, he built a coal-fired
steam engine for his bicycle, and at Cambridge University he produced
a single-cylinder gasoline motorcycle, incorporating many of
his own ideas, which won a fuel-economy competition when it traveled
almost 40 miles on a quart of gasoline. He also began development
of a two-cycle engine called the “Dolphin,” which later was
produced for use in fishing boats and automobiles. In fact, in 1911,
Ricardo took his new bride on their honeymoon trip in a Dolphinpowered
car.
The impetus that led to major engine research came in 1916
when Ricardo was an engineer in his family’s firm. The British
government asked for newly designed tank engines, which had to
operate in the dirt and mud of battle, at a tilt of up to 35 degrees,
and could not give off telltale clouds of blue oil smoke. Ricardo
solved the problem with a special piston design and with air circulation
around the carburetor and within the engine to keep the oil
cool.
Design work on the tank engines turned Ricardo into a fullfledged
research engineer. In 1917, he founded his own company,
and a remarkable series of discoveries quickly followed. He investigated
the problem of detonation of the fuel-air mixture in the internal
combustion cylinder. The mixture is supposed to be ignited
by the spark plug at the top of the compression stroke, with a controlled
flame front spreading at a rate about equal to the speed of
the piston head as it moves downward in the power stroke. Some
fuels, however, detonated (ignited spontaneously throughout the
entire fuel-air mixture) as a result of the compression itself, causing
loss of fuel efficiency and damage to the engine.
With the cooperation of Robert Waley Cohen of Shell Petroleum,
Ricardo evaluated chemical mixtures of fuels and found that paraffins
(such as n-heptane, the current low-octane standard) detonated
readily, but aromatics such as toluene were nearly immune to detonation.
He established a “toluene number” rating to describe the
tendency of various fuels to detonate; this number was replaced in

444 / Internal combustion engine
Standard Four-Stroke Internal Combustion Engine
Intake port Port
Spark plug Plug Exhaust Exhaust Port port
Intake Compression
Ignition Expansion
and Exhaust
Intake Compression Power Exhaust
The four cycles of a standard internal combustion engine (left to right): (1) intake, when air
enters the cylinder and mixes with gasoline vapor; (2) compression, when the cylinder is
sealed and the piston moves up to compress the air-fuel mixture; (3) power, when the spark
plug ignites the mixture, creating more pressure that propels the piston downward; and (4)
exhaust, when the burned gases exit the cylinder through the exhaust port.
the 1920’s by the “octane number” devised by Thomas Midgley at
the Delco laboratories in Dayton, Ohio.
The fuel work was carried out in an experimental engine designed
by Ricardo that allowed direct observation of the flame front
as it spread and permitted changes in compression ratio while the
engine was running. Three principles emerged from the investigation:
the fuel-air mixture should be admitted with as much turbulence
as possible, for thorough mixing and efficient combustion; the
spark plug should be centrally located to prevent distant pockets of
the mixture from detonating before the flame front reaches them;
and the mixture should be kept as cool as possible to prevent detonation.
These principles were then applied in the first truly efficient sidevalve
(“L-head”) engine—that is, an engine with the valves in a
chamber at the side of the cylinder, in the engine block, rather than
overhead, in the engine head. Ricardo patented this design, and after
winning a patent dispute in court in 1932, he received royalties
or consulting fees for it from engine manufacturers all over the
world.

Impact
The side-valve engine was the workhorse design for automobile
and marine engines until after World War II. With its valves actuated
directly by a camshaft in the crankcase, it is simple, rugged,
and easy to manufacture. Overhead valves with overhead camshafts
are the standard in automobile engines today, but the sidevalve
engine is still found in marine applications and in small engines
for lawn mowers, home generator systems, and the like. In its
widespread use and its decades of employment, the side-valve engine
represents a scientific and technological breakthrough in the
twentieth century.
Ricardo and his colleagues, Oliver Thornycroft and D. R. Pye,
went on to create other engine designs—notably, the sleeve-valve
aircraft engine that was the basic pattern for most of the great British
planes of World War II and early versions of the aircraft jet engine.
For his technical advances and service to the government, Ricardo
was elected a Fellow of the Royal Society in 1929, and he was
knighted in 1948.
See also Alkaline storage battery; Assembly line; Diesel locomotive;
Dirigible; Gas-electric car; Interchangeable parts; Thermal cracking
process.
Further Reading
Internal combustion engine / 445
A History of the Automotive Internal Combustion Engine. Warrendale,
Pa.: Society of Automotive Engineers, 1976.
Mowery, David C., and Nathan Rosenberg. Paths of Innovation: Technological
Change in Twentieth Century America. New York: Cambridge
University Press, 1999.
Ricardo, Harry R. Memories and Machines: The Pattern of My Life. London:
Constable, 1968.

446
The Internet
The Internet
The invention: A worldwide network of interlocking computer
systems, developed out of a U.S. government project to improve
military preparedness.
The people behind the invention:
Paul Baran, a researcher for the RAND corporation
Vinton G. Cerf (1943- ), an American computer scientist
regarded as the “father of the Internet”
Cold War Computer Systems
In 1957, the world was stunned by the launching of the satellite
Sputnik I by the Soviet Union. The international image of the United
States as the world’s technology superpower and its perceived edge
in the Cold War were instantly brought into question. As part of the
U.S. response, the Defense Department quickly created the Advanced
Research Projects Agency (ARPA) to conduct research into
“command, control, and communications” systems. Military planners
in the Pentagon ordered ARPA to develop a communications
network that would remain usable in the wake of a nuclear attack.
The solution, proposed by Paul Baran, a scientist at the RAND Corporation,
was the creation of a network of linked computers that
could route communications around damage to any part of the system.
Because the centralized control of data flow by major “hub”
computers would make such a system vulnerable, the system could
not have any central command, and all surviving points had to be
able to reestablish contact following an attack on any single point.
This redundancy of connectivity (later known as “packet switching”)
would not monopolize a single circuit for communications, as
telephones do, but would automatically break up computer messages
into smaller packets, each of which could reach a destination
by rerouting along different paths.
ARPA then began attempting to link university computers over
telephone lines. The historic connecting of four sites conducting
ARPA research was accomplished in 1969 at a computer laboratory

at the University of California at Los Angeles (UCLA), which was
connected to computers at the University of California at Santa
Barbara, the Stanford Research Institute, and the University of Utah.
UCLA graduate student Vinton Cerf played a major role in establishing
the connection, which was first known as “ARPAnet.” By
1971, more than twenty sites had been connected to the network, including
supercomputers at the Massachusetts Institute of Technology
and Harvard University; by 1981, there were more than two
hundred computers on the system.
The Development of the Internet
The Internet / 447
Because factors such as equipment failure, overtaxed telecommunications
lines, and power outages can quickly reduce or abort
(“crash”) computer network performance, the ARPAnet managers
and others quickly sought to build still larger “internetting” projects.
In the late 1980’s, the National Science Foundation built its
own network of five supercomputer centers to give academic researchers
access to high-power computers that had previously been
available only to military contractors. The “NSFnet” connected university
networks by linking them to the closest regional center; its
development put ARPAnet out of commission in 1990. The economic
savings that could be gained from the use of electronic mail
(“e-mail”), which reduced postage and telephone costs, were motivation
enough for many businesses and institutions to invest in
hardware and network connections.
The evolution of ARPAnet and NSFnet eventually led to the creation
of the “Internet,” an international web of interconnected government,
education, and business computer networks that has been
called “the largest machine ever constructed.” Using appropriate
software, a computer terminal or personal computer can send and
receive data via an “Internet Protocol” packet (an electronic envelope
with an address). Communications programs on the intervening
networks “read” the addresses on packets moving through the
Internet and forward the packets toward their destinations. From
approximately one thousand networks in the mid-1980’s, the Internet
grew to an estimated thirty thousand connected networks by
1994, with an estimated 25 million users accessing it regularly. The

448 / The Internet
Vinton Cerf
Although Vinton Cerf is widely hailed as the “father of the
Internet,” he himself disavows that honor. He has repeatedly
emphasized that the Internet was built on the work of countless
others, and that he and his partner merely happened to make a
crucial contribution at a turning point in Internet development.
The path leading Cerf to the Internet began early. He was
born in New Haven, Connecticut, in 1943. He read widely, devouring
L. Frank Baum’s Oz books and science fiction novels—
especially those dealing with real-science themes. When he was
ten, a book called The Boy Scientist fired his interest in science.
After starting high school in Los Angeles in 1958, he got his first
glimpse of computers, which were very different devices in
those days. During a visit to a Santa Monica lab, he inspected a
computer filling three rooms with wires and vacuum tubes that
analyzed data from a Canadian radar system built to detect
sneak missile attacks from the Soviet Union. Two years later he
and a friend began programming a paper-tape computer at
UCLA while they were still in high school.
After graduating from Stanford University in 1965 with a
degree in computer science, Cerf worked for IBM for two years,
then entered graduate school at UCLA. His work on multiprocessing
computer systems got sidetracked when a Defense
Department request came in asking for help on a packet-switching
project. This new project drew him into the brand-new field
of computer networking on a system that became known as the
ARPAnet. In 1972 Cerf returned to Stanford as an assistant professor.
There he and a colleague, Robert Kahn, developed the
concepts and protocols that became the basis of the modern Internet—a
term they coined in a paper they delivered in 1974.
Afterward Cerf made development of the Internet the focus
of his distinguished career, and he later moved back into the
business world. In 1994 he returned to MCI as senior vice president
of Internet architecture. Meanwhile, he founded the Internet
Society in 1992 and the Internet Societal Task Force in 1999.
majority of Internet users live in the United States and Europe, but
the Internet has continued to expand internationally as telecommunications
lines are improved in other countries.

Impact
Most individual users access the Internet through modems attached
to their home personal computers by subscribing to local area
networks. These services make information sources available such as
on-line encyclopedias and magazines and embrace electronic discussion
groups and bulletin boards on nearly every specialized interest
area imaginable. Many universities converted large libraries to electronic
form for Internet distribution, with an ambitious example being
Cornell University’s conversion to electronic form of more than
100,000 books on the development of America’s infrastructure.
Numerous corporations and small businesses soon began to
market their products and services over the Internet. Problems soon
became apparent with the commercial use of the new medium,
however, as the protection of copyrighted material proved to be difficult;
data and other text available on the system can be “downloaded,”
or electronically copied. To protect their resources from
unauthorized use via the Internet, therefore, most companies set up
a “firewall” computer to screen incoming communications.
The economic policies of the Bill Clinton administration highlighted
the development of the “information superhighway” for
improving the delivery of social services and encouraging new
businesses; however, many governmental agencies and offices, including
the U.S. Senate and House of Representative, have been
slow to install high-speed fiber-optic network links. Nevertheless,
the Internet soon came to contain numerous information sites to improve
public access to the institutions of government.
See also Cell phone; Communications satellite; Fax machine;
Personal computer.
Further Reading
The Internet / 449
Abbate, Janet. Inventing the Internet. Cambridge, Mass.: MIT Press,
2000.
Brody, Herb. “Net Cerfing.” Technology Review (Cambridge, Mass.)
101, no. 3 (May-June, 1998).
Bryant, Stephen. The Story of the Internet. London: Peason Education,
2000.

450 / The Internet
Rodriguez, Karen. “Plenty Deserve Credit as ‘Father’ of the Internet.”
Business Journal 17, no. 27 (October 22, 1999).
Stefik, Mark J., and Vinton Cerf. Internet Dreams: Archetypes, Myths,
and Metaphors. Cambridge, Mass.: MIT Press, 1997.
“Vint Cerf.” Forbes 160, no. 7 (October 6, 1997).
Wollinsky, Art. The History of the Internet and the World Wide Web.
Berkeley Heights, N.J.: Enslow, 1999.

Iron lung
Iron lung
The invention: A mechanical respirator that saved the lives of victims
of poliomyelitis.
The people behind the invention:
Philip Drinker (1894-1972), an engineer who made many
contributions to medicine
Louis Shaw (1886-1940), a respiratory physiologist who
assisted Drinker
Charles F. McKhann III (1898-1988), a pediatrician and
founding member of the American Board of Pediatrics
A Terrifying Disease
451
Poliomyelitis (polio, or infantile paralysis) is an infectious viral
disease that damages the central nervous system, causing paralysis
in many cases. Its effect results from the destruction of neurons
(nerve cells) in the spinal cord. In many cases, the disease produces
crippled limbs and the wasting away of muscles. In others, polio results
in the fatal paralysis of the respiratory muscles. It is fortunate
that use of the Salk and Sabin vaccines beginning in the 1950’s has
virtually eradicated the disease.
In the 1920’s, poliomyelitis was a terrifying disease. Paralysis of
the respiratory muscles caused rapid death by suffocation, often
within only a few hours after the first signs of respiratory distress
had appeared. In 1929, Philip Drinker and Louis Shaw, both of Harvard
University, reported the development of a mechanical respirator
that would keep those afflicted with the disease alive for indefinite
periods of time. This device, soon nicknamed the “iron lung,”
helped thousands of people who suffered from respiratory paralysis
as a result of poliomyelitis or other diseases.
Development of the iron lung arose after Drinker, then an assistant
professor in Harvard’s Department of Industrial Hygiene, was
appointed to a Rockefeller Institute commission formed to improve
methods for resuscitating victims of electric shock. The best-known
use of the iron lung—treatment of poliomyelitis—was a result of
numerous epidemics of the disease that occurred from 1898 until

452 / Iron lung
the 1920’s, each leaving thousands of Americans paralyzed.
The concept of the iron lung reportedly arose from Drinker’s observation
of physiological experiments carried out by Shaw and
Drinker’s brother, Cecil. The experiments involved the placement
of a cat inside an airtight box—a body plethysmograph—with the
cat’s head protruding from an airtight collar. Shaw and Cecil Drinker
then measured the volume changes in the plethysmograph to identify
normal breathing patterns. Philip Drinker then placed cats paralyzed
by curare inside plethysmographies and showed that they
could be kept breathing artificially by use of air from a hypodermic
syringe connected to the device.
Next, they proceeded to build a human-sized plethysmographlike
machine, with a five-hundred-dollar grant from the New York
Consolidated Gas Company. This was done by a tinsmith and the
Harvard Medical School machine shop.
Breath for Paralyzed Lungs
The first machine was tested on Drinker and Shaw, and after several
modifications were made, a workable iron lung was made
available for clinical use. This machine consisted of a metal cylinder
large enough to hold a human being. One end of the cylinder, which
contained a rubber collar, slid out on casters along with a stretcher
on which the patient was placed. Once the patient was in position
and the collar was fitted around the patient’s neck, the stretcher was
pushed back into the cylinder and the iron lung was made airtight.
The iron lung then “breathed” for the patient by using an electric
blower to remove and replace air alternatively inside the machine.
In the human chest, inhalation occurs when the diaphragm contracts
and powerful muscles (which are paralyzed in poliomyelitis
sufferers) expand the rib cage. This lowers the air pressure in the
lungs and allows inhalation to occur. In exhalation, the diaphragm
and chest muscles relax, and air is expelled as the chest cavity returns
to its normal size. In cases of respiratory paralysis treated with
an iron lung, the air coming into or leaving the iron lung alternately
compressed the patient’s chest, producing artificial exhalation, and
the allowed it to expand to so that the chest could fill with air. In this
way, iron lungs “breathed” for the patients using them.

Careful examination of each patient was required to allow technicians
to adjust the rate of operation of the machine. A cooling system
and ports for drainage lines, intravenous lines, and the other
apparatus needed to maintain a wide variety of patients were included
in the machine.
The first person treated in an iron lung was an eight-year-old girl
afflicted with respiratory paralysis resulting from poliomyelitis. The
iron lung kept her alive for five days. Unfortunately, she died from
heart failure as a result of pneumonia. The next iron lung patient, a
Harvard University student, was confined to the machine for several
weeks and later recovered enough to resume a normal life.
Impact
The Drinker respirator, or iron lung, came into use in 1929 and
soon was considered indispensable, saving lives of poliomyelitis
victims until the development of the Salk vaccine in the 1950’s.
Although the iron lung is no longer used, it played a critical role
in the development of modern respiratory care, proving that large
numbers of patients could be kept alive with mechanical support.
The iron lung and polio treatment began an entirely new era in
treatment of respiratory conditions.
In addition to receiving a number of awards and honorary degrees
for his work, Drinker was elected president of the American
Industrial Hygiene Association in 1942 and became chairman of
Harvard’s Department of Industrial Hygiene.
See also Electrocardiogram; Electroencephalogram; Heart-lung
machine; Pacemaker; Polio vaccine (Sabin); Polio vaccine (Salk).
Further Reading
Iron lung / 453
DeJauregui, Ruth. One Hundred Medical Milestones That Shaped World
History. San Mateo, Calif.: Bluewood Books, 1998.
Hawkins, Leonard C. The Man in the Iron Lung: The Frederick B. Snite,
Jr., Story. Garden City, N.Y.: Doubleday, 1956.
Rudulph, Mimi. Inside the Iron Lung. Buckinghamshire: Kensal
Press, 1984.

454
Laminated glass
Laminated glass
The invention: Double sheets of glass separated by a thin layer of
plastic sandwiched between them.
The people behind the invention:
Edouard Benedictus (1879-1930), a French artist
Katherine Burr Blodgett (1898-1979), an American physicist
The Quest for Unbreakable Glass
People have been fascinated for centuries by the delicate transparency
of glass and the glitter of crystals. They have also been frustrated
by the brittleness and fragility of glass. When glass breaks, it
forms sharp pieces that can cut people severely. During the 1800’s
and early 1900’s, a number of people demonstrated ways to make
“unbreakable” glass. In 1855 in England, the first “unbreakable”
glass panes were made by embedding thin wires in the glass. The
embedded wire grid held the glass together when it was struck or
subjected to the intense heat of a fire. Wire glass is still used in windows
that must be fire resistant. The concept of embedding the wire
within a glass sheet so that the glass would not shatter was a predecessor
of the concept of laminated glass.
A series of inventors in Europe and the United States worked on
the idea of using a durable, transparent inner layer of plastic between
two sheets of glass to prevent the glass from shattering when it was
dropped or struck by an impact. In 1899, Charles E. Wade of Scranton,
Pennsylvania, obtained a patent for a kind of glass that had a sheet or
netting of mica fused within it to bind it. In 1902, Earnest E. G. Street
of Paris, France, proposed coating glass battery jars with pyroxylin
plastic (celluloid) so that they would hold together if they cracked. In
Swindon, England, in 1905, John Crewe Wood applied for a patent
for a material that would prevent automobile windshields from shattering
and injuring people when they broke. He proposed cementing
a sheet of material such as celluloid between two sheets of glass.
When the window was broken, the inner material would hold the
glass splinters together so that they would not cut anyone.

Katharine Burr Blodgett
Remembering a Fortuitous Fall
Laminated glass / 455
Besides the danger of shattering, glass poses another problem.
It reflects light, as much as 10 percent of the rays hitting it,
and that is bad for many precision instruments. Katharine Burr
Blodgett cleared away that problem.
Blodgett was born in 1898 in Schenectady, New York, just
months after her father died. Her widowed mother, intent upon
giving her and her brother the best upbringing possible, devoted
herself to their education and took them abroad to live for
extended periods. She succeeded. Blodgett attended Bryn Mawr
and then earned a master’s degree in physics from the University
of Chicago. With the help of a family friend, Irving Langmuir,
who later won a Nobel Prize in Chemistry, she was promised
a job at the General Electric (GE) research laboratory.
However, Langmuir first wanted her to study more physics.
Blodgett went to Cambridge University and under the guidance
of Ernest Rutherford became the first women to receive a
doctorate in physics there. Then she went to work at GE.
Collaborating with Langmuir, Blodgett found that she could
coat glass with a film one layer of molecules at a time, a feat
never accomplished before. Moreover, the color of light reflected
differed with the number of layers of film. She discovered
that by adjusting the number of layers she could cancel out
the light reflected by the glass beneath, so as much as 99 percent
of natural light would pass through the glass. Producing almost
no reflection, this treated glass was “invisible.” It was perfect
for lenses, such as those in cameras and microscopes. Blodgett
also devised a way to measure the thickness of films based on
the wavelengths of light they reflect—a color gauge—that became
a standard laboratory technique.
Blodgett died in the town of her birth in 1979.
In his patent application, Edouard Benedictus described himself
as an artist and painter. He was also a poet, musician, and
philosopher who was descended from the philosopher Baruch
Benedictus Spinoza; he seemed an unlikely contributor to the
progress of glass manufacture. In 1903, Benedictus was cleaning

456 / Laminated glass
his laboratory when he dropped a glass bottle that held a nitrocellulose
solution. The solvents, which had evaporated during the
years that the bottle had sat on a shelf, had left a strong celluloid
coating on the glass. When Benedictus picked up the bottle, he was
surprised to see that it had not shattered: It was starred, but all the
glass fragments had been held together by the internal celluloid
coating. He looked at the bottle closely, labeled it with the date
(November, 1903) and the height from which it had fallen, and put
it back on the shelf.
One day some years later (the date is uncertain), Benedictus became
aware of vehicular collisions in which two young women received
serious lacerations from broken glass. He wrote a poetic account
of a daydream he had while he was thinking intently about
the two women. He described a vision in which the faintly illuminated
bottle that had fallen some years before but had not shattered
appeared to float down to him from the shelf. He got up, went into
his laboratory, and began to work on an idea that originated with his
thoughts of the bottle that would not splinter.
Benedictus found the old bottle and devised a series of experiments
that he carried out until the next evening. By the time he had
finished, he had made the first sheet of Triplex glass, for which he
applied for a patent in 1909. He also founded the Société du Verre
Triplex (The Triplex Glass Society) in that year. In 1912, the Triplex
Safety Glass Company was established in England. The company
sold its products for military equipment in World War I, which began
two years later.
Triplex glass was the predecessor of laminated glass. Laminated
glass is composed of two or more sheets of glass with a thin
layer of plastic (usually polyvinyl butyral, although Benedictus
used pyroxylin) laminated between the glass sheets using pressure
and heat. The plastic layer will yield rather than rupture when subjected
to loads and stresses. This prevents the glass from shattering
into sharp pieces. Because of this property, laminated glass is also
known as “safety glass.”
Impact
Even after the protective value of laminated glass was known,

the product was not widely used for some years. There were a number
of technical difficulties that had to be solved, such as the discoloring
of the plastic layer when it was exposed to sunlight; the relatively
high cost; and the cloudiness of the plastic layer, which
obscured vision—especially at night. Nevertheless, the expanding
automobile industry and the corresponding increase in the number
of accidents provided the impetus for improving the qualities and
manufacturing processes of laminated glass. In the early part of the
century, almost two-thirds of all injuries suffered in automobile accidents
involved broken glass.
Laminated glass is used in many applications in which safety is
important. It is typically used in all windows in cars, trucks, ships,
and aircraft. Thick sheets of bullet-resistant laminated glass are
used in banks, jewelry displays, and military installations. Thinner
sheets of laminated glass are used as security glass in museums, libraries,
and other areas where resistance to break-in attempts is
needed. Many buildings have large ceiling skylights that are made
of laminated glass; if the glass is damaged, it will not shatter, fall,
and hurt people below. Laminated glass is used in airports, hotels,
and apartments in noisy areas and in recording studios to reduce
the amount of noise that is transmitted. It is also used in safety goggles
and in viewing ports at industrial plants and test chambers.
Edouard Benedictus’s recollection of the bottle that fell but did not
shatter has thus helped make many situations in which glass is used
safer for everyone.
See also Buna rubber; Contact lenses; Neoprene; Plastic; Pyrex
glass; Silicones.
Further Reading
Laminated glass / 457
Eastman, Joel W. Styling vs. Safety: The American Automobile Industry
and the Development of Automotive Safety, 1900-1966. Lanham: University
Press of America, 1984.
Fariss, Robert H. “Fifty Years of Safer Windshields.” CHEMTECH
23, no. 9 (September, 1993).
Miel, Rhoda. “New Process Promises Safer Glass.” Automotive News
74, no. 5863 (February 28, 2000).

458 / Laminated glass
Polak, James L. “Eighty Years Plus of Automotive Glass Development:
Windshields Were Once an Option, Today They Are an Integral
Part of the Automobile.” Automotive Engineering 98, no. 6
(June, 1990).

Laser
Laser
The invention: Taking its name from the acronym for light amplification
by the stimulated emission of radiation, a laser is a
beam of electromagnetic radiation that is monochromatic, highly
directional, and coherent. Lasers have found multiple applications
in electronics, medicine, and other fields.
The people behind the invention:
Theodore Harold Maiman (1927- ), an American physicist
Charles Hard Townes (1915- ), an American physicist who
was a cowinner of the 1964 Nobel Prize in Physics
Arthur L. Schawlow (1921-1999), an American physicist,
cowinner of the 1981 Nobel Prize in Physics
Mary Spaeth (1938- ), the American inventor of the tunable
laser
Coherent Light
459
Laser beams differ from other forms of electromagnetic radiation
in being consisting of a single wavelength, being highly directional,
and having waves whose crests and troughs are aligned. A laser
beam launched from Earth has produced a spot a few kilometers
wide on the Moon, nearly 400,000 kilometers away. Ordinary light
would have spread much more and produced a spot several times
wider than the Moon. Laser light can also be concentrated so as to
yield an enormous intensity of energy, more than that of the surface
of the Sun, an impossibility with ordinary light.
In order to appreciate the difference between laser light and ordinary
light, one must examine how light of any kind is produced. An
ordinary light bulb contains atoms of gas. For the bulb to light up,
these atoms must be excited to a state of energy higher then their
normal, or ground, state. This is accomplished by sending a current
of electricity through the bulb; the current jolts the atoms into the
higher-energy state. This excited state is unstable, however, and the
atoms will spontaneously return to their ground state by ridding
themselves of excess energy.

460 / Laser
Scanner device using a laser beam to read shelf labels. (PhotoDisc)
As these atoms emit energy, light is produced. The light emitted
by a lamp full of atoms is disorganized and emitted in all directions
randomly. This type of light, common to all ordinary sources, from
fluorescent lamps to the Sun, is called “incoherent light.”
Laser light is different. The excited atoms in a laser emit their excess
energy in a unified, controlled manner. The atoms remain in the
excited state until there are a great many excited atoms. Then, they
are stimulated to emit energy, not independently, but in an organized
fashion, with all their light waves traveling in the same direction,
crests and troughs perfectly aligned. This type of light is called
“coherent light.”
Theory to Reality
In 1958, Charles Hard Townes of Columbia University, together
with Arthur L. Schawlow, explored the requirements of the laser in
a theoretical paper. In the Soviet Union, F. A. Butayeva and V. A.
Fabrikant had amplified light in 1957 using mercury; however, their
work was not published for two years and was not published in a
scientific journal. The work of the Soviet scientists, therefore, re-

Mary Spaeth
Born in 1938, Mary Dietrich Spaeth, inventor of the tunable
laser, learned to put things together early. When she was just
three years old, her father began giving her tools to play with.
She learned to use them well and got interested in science along
the way. She studied mathematics and physics at Valparaiso
University, graduating in 1960, and earned a master’s degree in
nuclear physics from Wayne State University in 1962.
The same year she joined Hughes Aircraft Company as a researcher.
While waiting for supplies for her regular research in
1966, she examined the lasers in her laboratory. She wondered
if, by adding dyes, she could cause the beams to change colors.
Cobbling together two lasers—one to boost the power of the
test laser—with Duco cement, she added dyes and succeeded at
once. She found that she could produce light in a wide range of
colors with different dyes. The tunable dye laser afterward was
used to separate isotopes in nuclear reactor fuel, to purify plutonium
for weapons, and to boost the power of ground-based
astronomical telescopes. She also invented a resonant reflector
for ruby range finders and performed basic research on passive
Q switches used in lasers.
Because Spaeth considered Hughes’s promotion policies to
discriminate against women scientists, she moved to the Lawrence
Livermore National Laboratory in 1974. In 1986 she became
the deputy associate director of its Laser Isotope Separation
program.
Laser / 461
ceived virtually no attention in the Western world.
In 1960, Theodore Harold Maiman constructed the first laser in
the United States using a single crystal of synthetic pink ruby,
shaped into a cylindrical rod about 4 centimeters long and 0.5 centimeter
across. The ends, polished flat and made parallel to within
about a millionth of a centimeter, were coated with silver to make
them mirrors.
It is a property of stimulated emission that stimulated light
waves will be aligned exactly (crest to crest, trough to trough, and
with respect to direction) with the radiation that does the stimulating.
From the group of excited atoms, one atom returns to its ground

462 / Laser
state, emitting light. That light hits one of the other exited atoms and
stimulates it to fall to its ground state and emit light. The two light
waves are exactly in step. The light from these two atoms hits other
excited atoms, which respond in the same way, “amplifying” the total
sum of light.
If the first atom emits light in a direction parallel to the length of
the crystal cylinder, the mirrors at both ends bounce the light waves
back and forth, stimulating more light and steadily building up an
increasing intensity of light. The mirror at one end of the cylinder is
constructed to let through a fraction of the light, enabling the light to
emerge as a straight, intense, narrow beam.
Consequences
When the laser was introduced, it was an immediate sensation. In
the eighteen months following Maiman’s announcement that he had
succeeded in producing a working laser, about four hundred companies
and several government agencies embarked on work involving
lasers. Activity centered on improving lasers, as well as on exploring
their applications. At the same time, there was equal activity in publicizing
the near-miraculous promise of the device, in applications covering
the spectrum from “death” rays to sight-saving operations. A
popular film in the James Bond series, Goldfinger (1964), showed the
hero under threat of being sliced in half by a laser beam—an impossibility
at the time the film was made because of the low power-output
of the early lasers.
In the first decade after Maiman’s laser, there was some disappointment.
Successful use of lasers was limited to certain areas of
medicine, such as repairing detached retinas, and to scientific applications,
particularly in connection with standards: The speed of
light was measured with great accuracy, as was the distance to the
Moon. By 1990, partly because of advances in other fields, essentially
all the laser’s promise had been fulfilled, including the death
ray and James Bond’s slicer. Yet the laser continued to find its place
in technologies not envisioned at the time of the first laser. For example,
lasers are now used in computer printers, in compact disc
players, and even in arterial surgery.

See also Atomic clock; Compact disc; Fiber-optics; Holography;
Laser-diode recording process; Laser vaporization; Optical disk.
Further Reading
Laser / 463
Townes, Charles H. How the Laser Happened: Adventures of a Scientist.
New York: Oxford University Press, 1999.
Weber, Robert L. Pioneers of Science: Nobel Prize Winners in Physics.2d
ed. Philadelphia: A. Hilger, 1988.
Yen, W. M., Marc D. Levenson, and Arthur L. Schawlow. Lasers,
Spectroscopy, and New Ideas: A Tribute to Arthur L. Schawlow. New
York: Springer-Verlag, 1987.

464
Laser-diode recording process
Laser-diode recording process
The invention: Video and audio playback system that uses a lowpower
laser to decode information digitally stored on reflective
disks.
The organization behind the invention:
The Philips Corporation, a Dutch electronics firm
The Development of Digital Systems
Since the advent of the computer age, it has been the goal of
many equipment manufacturers to provide reliable digital systems
for the storage and retrieval of video and audio programs. A need
for such devices was perceived for several reasons. Existing storage
media (movie film and 12-inch, vinyl, long-playing records) were
relatively large and cumbersome to manipulate and were prone to
degradation, breakage, and unwanted noise. Thus, during the late
1960’s, two different methods for storing video programs on disc
were invented. A mechanical system was demonstrated by the
Telefunken Company, while the Radio Corporation of America
(RCA) introduced an electrostatic device (a device that used static
electricity). The first commercially successful system, however, was
developed during the mid-1970’s by the Philips Corporation.
Philips devoted considerable resources to creating a digital video
system, read by light beams, which could reproduce an entire feature-length
film from one 12-inch videodisc. An integral part of this
innovation was the fabrication of a device small enough and fast
enough to read the vast amounts of greatly compacted data stored
on the 12-inch disc without introducing unwanted noise. Although
Philips was aware of the other formats, the company opted to use an
optical scanner with a small “semiconductor laser diode” to retrieve
the digital information. The laser diode is only a fraction of a millimeter
in size, operates quite efficiently with high amplitude and relatively
low power (0.1 watt), and can be used continuously. Because
this configuration operates at a high frequency, its informationcarrying
capacity is quite large.

Although the digital videodisc system (called “laservision”) works
well, the low level of noise and the clear images offered by this system
were masked by the low quality of the conventional television
monitors on which they were viewed. Furthermore, the high price
of the playback systems and the discs made them noncompetitive
with the videocassette recorders (VCRs) that were then capturing
the market for home systems. VCRs had the additional advantage
that programs could be recorded or copied easily. The Philips Corporation
turned its attention to utilizing this technology in an area
where low noise levels and high quality would be more readily apparent—audio
disc systems. By 1979, they had perfected the basic
compact disc (CD) system, which soon revolutionized the world of
stereophonic home systems.
Reading Digital Discs with Laser Light
Laser-diode recording process / 465
Digital signals (signals composed of numbers) are stored on
discs as “pits” impressed into the plastic disc and then coated with a
thin reflective layer of aluminum. A laser beam, manipulated by
delicate, fast-moving mirrors, tracks and reads the digital information
as changes in light intensity. These data are then converted to a
varying electrical signal that contains the video or audio information.
The data are then recovered by means of a sophisticated
pickup that consists of the semiconductor laser diode, a polarizing
beam splitter, an objective lens, a collective lens system, and a
photodiode receiver. The beam from the laser diode is focused by a
collimator lens (a lens that collects and focuses light) and then
passes through the polarizing beam splitter (PBS). This device acts
like a one-way mirror mounted at 45 degrees to the light path. Light
from the laser passes through the PBS as if it were a window, but the
light emerges in a polarized state (which means that the vibration of
the light takes place in only one plane). For the beam reflected from
the CD surface, however, the PBS acts like a mirror, since the reflected
beam has an opposite polarization. The light is thus deflected
toward the photodiode detector. The objective lens is needed
to focus the light onto the disc surface. On the outer surface of the
transparent disc, the main spot of light has a diameter of 0.8 millimeter,
which narrows to only 0.0017 millimeter at the reflective sur-

466 / Laser-diode recording process
face. At the surface, the spot is about three times the size of the microscopic
pits (0.0005 millimeter).
The data encoded on the disc determine the relative intensity of
the reflected light, on the basis of the presence or absence of pits.
When the reflected laser beam enters the photodiode, a modulated
light beam is changed into a digital signal that becomes an analog
(continuous) audio signal after several stages of signal processing
and error correction.
Consequences
The development of the semiconductor laser diode and associated
circuitry for reading stored information has made CD audio
systems practical and affordable. These systems can offer the quality
of a live musical performance with a clarity that is undisturbed
by noise and distortion. Digital systems also offer several other significant
advantages over analog devices. The dynamic range (the
difference between the softest and the loudest signals that can be
stored and reproduced) is considerably greater in digital systems. In
addition, digital systems can be copied precisely; the signal is not
degraded by copying, as is the case with analog systems. Finally,
error-correcting codes can be used to detect and correct errors in
transmitted or reproduced digital signals, allowing greater precision
and a higher-quality output sound.
Besides laser video systems, there are many other applications
for laser-read CDs. Compact disc read-only memory (CD-ROM) is
used to store computer text. One standard CD can store 500 megabytes
of information, which is about twenty times the storage of a
hard-disk drive on a typical home computer. Compact disc systems
can also be integrated with conventional televisions (called CD-V)
to present twenty minutes of sound and five minutes of sound with
picture. Finally, CD systems connected with a computer (CD-I) mix
audio, video, and computer programming. These devices allow the
user to stop at any point in the program, request more information,
and receive that information as sound with graphics, film clips, or
as text on the screen.
See also Compact disc; Laser; Videocassette recorder; Walkman
cassette player.

Further Reading
Laser-diode recording process / 467
Atkinson, Terry. “Picture This: CD’s with Video, By Christmas ‘87.”
Los Angeles Times (February 20, 1987).
Botez, Dan, and Luis Figueroa. Laser-Diode Technology and Applications
II: 16-19 January 1990, Los Angeles, California. Bellingham,
Wash.: SPIE, 1990.
Clemens, Jon K. “Video Disks: Three Choices.” IEEE Spectrum 19,
no. 3 (March, 1982).
“Self-Pulsating Laser for DVD.” Electronics Now 67, no. 5 (May,
1996).

468
Laser eye surgery
Laser eye surgery
The invention: The first significant clinical ophthalmic application
of any laser system was the treatment of retinal tears with a
pulsed ruby laser.
The people behind the invention:
Charles J. Campbell (1926- ), an ophthalmologist
H. Christian Zweng (1925- ), an ophthalmologist
Milton M. Zaret (1927- ), an ophthalmologist
Theodore Harold Maiman (1927- ), the physicist who
developed the first laser
Monkeys and Rabbits
The term “laser” is an acronym for light amplification by the
stimulated emission of radiation. The development of the laser for
ophthalmic (eye surgery) surgery arose from the initial concentration
of conventional light by magnifying lenses.
Within a laser, atoms are highly energized. When one of these atoms
loses its energy in the form of light, it stimulates other atoms to
emit light of the same frequency and in the same direction. A cascade
of these identical light waves is soon produced, which then oscillate
back and forth between the mirrors in the laser cavity. One
mirror is only partially reflective, allowing some of the laser light to
pass through. This light can be concentrated further into a small
burst of high intensity.
On July 7, 1960, Theodore Harold Maiman made public his discovery
of the first laser—a ruby laser. Shortly thereafter, ophthalmologists
began using ruby lasers for medical purposes.
The first significant medical uses of the ruby laser occurred in
1961, with experiments on animals conducted by Charles J. Campbell
in New York, H. Christian Zweng, and Milton M. Zaret. Zaret and his
colleagues produced photocoagulation (a thickening or drawing together
of substances by use of light) of the eyes of rabbits by flashes
from a ruby laser. Sufficient energy was delivered to cause immediate
thermal injury to the retina and iris of the rabbit. The beam also was

directed to the interior of the rabbit eye, resulting in retinal coagulations.
The team examined the retinal lesions and pointed out both
the possible advantages of laser as a tool for therapeutic photocoagulation
and the potential applications in medical research.
In 1962, Zweng, along with several of his associates, began experimenting
with laser photocoagulation on the eyes of monkeys
and rabbits in order to establish parameters for the use of lasers on
the human eye.
Reflected by Blood
Laser eye surgery / 469
The vitreous humor, a transparent jelly that usually fills the vitreous
cavity of the eyes of younger individuals, commonly shrinks with age,
with myopia, or with certain pathologic conditions. As these conditions
occur, the vitreous humor begins to separate from the adjacent
retina. In some patients, the separating vitreous humor produces a
traction (pulling), causing a retinal tear to form. Through this opening in
the retina, liquefied vitreous humor can pass to a site underneath the
retina, producing retinal detachment and loss of vision.
Alaser can be used to cause photocoagulation of a retinal tear. As a
result, an adhesive scar forms between the retina surrounding the
tear and the underlying layers so that, despite traction, the retina
does not detach. If more than a small area of retina has detached, the
laser often is ineffective and major retinal detachment surgery must
be performed. Thus, in the experiments of Campbell and Zweng, the
ruby laser was used to prevent, rather than treat, retinal detachment.
In subsequent experiments with humans, all patients were treated
with the experimental laser photocoagulator without anesthesia.
Although usually no attempt was made to seal holes or tears, the
diseased portions of the retina were walled off satisfactorily so that
no detachments occurred. One problem that arose involved microaneurysms.
A “microaneurysm” is a tiny aneurysm, or blood-filled
bubble extending from the wall of a blood vessel. When attempts to
obliterate microaneurysms were unsuccessful, the researchers postulated
that the color of the ruby pulse so resembled the red of blood
that the light was reflected rather than absorbed. They believed that
another lasing material emitting light in another part of the spectrum
might have performed more successfully.

470 / Laser eye surgery
Previously, xenon-arc lamp photocoagulators had been used to
treat retinal tears. The long exposure time required of these systems,
combined with their broad spectral range emission (versus
the single wavelength output of a laser), however, made the retinal
spot on which the xenon-arc could be focused too large for many
applications. Focused laser spots on the retina could be as small as
50 microns.
Consequences
The first laser in ophthalmic use by Campbell, Zweng, and Zaret,
among others, was a solid laser—Maiman’s ruby laser. While the results
they achieved with this laser were more impressive than with
the previously used xenon-arc, in the decades following these experiments,
argon gas replaced ruby as the most frequently used material
in treating retinal tears.
Argon laser energy is delivered to the area around the retinal tear
through a slit lamp or by using an intraocular probe introduced directly
into the eye. The argon wavelength is transmitted through the
clear structures of the eye, such as the cornea, lens, and vitreous.
This beam is composed of blue-green light that can be effectively
aimed at the desired portion of the eye. Nevertheless, the beam can
be absorbed by cataracts and by vitreous or retinal blood, decreasing
its effectiveness.
Moreover, while the ruby laser was found to be highly effective
in producing an adhesive scar, it was not useful in the treatment of
vascular diseases of the eye. A series of laser sources, each with different
characteristics, was considered, investigated, and used clinically
for various durations during the period that followed Campbell
and Zweng’s experiments.
Other laser types that are being adapted for use in ophthalmology
are carbon dioxide lasers for scleral surgery (surgery on the
tough, white, fibrous membrane covering the entire eyeball except
the area covered by the cornea) and eye wall resection, dye lasers to
kill or slow the growth of tumors, eximer lasers for their ability to
break down corneal tissue without heating, and pulsed erbium lasers
used to cut intraocular membranes.

See also Contact lenses; Coronary artery bypass surgery; Laser;
Laser vaporization.
Further Reading
Laser eye surgery / 471
Constable, Ian J., and Arthur Siew Ming Lin. Laser: Its Clinical Uses
in Eye Diseases. Edinburgh: Churchill Livingstone, 1981.
Guyer, David R. Retina, Vitreous, Macula. Philadelphia: Saunders,
1999.
Hecht, Jeff. Laser Pioneers. Rev. ed. Boston: Academic Press, 1992.
Smiddy, William E., Lawrence P. Chong, and Donald A. Frambach.
Retinal Surgery and Ocular Trauma. Philadelphia: Lippincott, 1995.

472
Laser vaporization
Laser vaporization
The invention: Technique using laser light beams to vaporize the
plaque that clogs arteries.
The people behind the invention:
Albert Einstein (1879-1955), a theoretical American physicist
Theodore Harold Maiman (1927- ), inventor of the laser
Light, Lasers, and Coronary Arteries
Visible light, a type of electromagnetic radiation, is actually a
form of energy. The fact that the light beams produced by a light
bulb can warm an object demonstrates that this is the case. Light
beams are radiated in all directions by a light bulb. In contrast, the
device called the “laser” produces light that travels in the form of a
“coherent” unidirectional beam. Coherent light beams can be focused
on very small areas, generating sufficient heat to melt steel.
The term “laser” was invented in 1957 by R. Gordon Gould of
Columbia University. It stands for light amplification by stimulated
emission of radiation, the means by which laser light beams are
made. Many different materials—including solid ruby gemstones,
liquid dye solutions, and mixtures of gases—can produce such
beams in a process called “lasing.” The different types of lasers yield
light beams of different colors that have many uses in science, industry,
and medicine. For example, ruby lasers, which were developed
in 1960, are widely used in eye surgery. In 1983, a group of
physicians in Toulouse, France, used a laser for cardiovascular treatment.
They used the laser to vaporize the “atheroma” material that
clogs the arteries in the condition called “atherosclerosis.” The technique
that they used is known as “laser vaporization surgery.”
Laser Operation, Welding, and Surgery
Lasers are electronic devices that emit intense beams of light
when a process called “stimulated emission” occurs. The principles
of laser operation, including stimulated emission, were established
by Albert Einstein and other scientists in the first third of the twenti-

Laser vaporization / 473
eth century. In 1960, Theodore H. Maiman of the Hughes Research
Center in Malibu, California, built the first laser, using a ruby crystal
to produce a laser beam composed of red light.
All lasers are made up of three main components. The first of
these, the laser’s “active medium,” is a solid (like Maiman’s ruby
crystal), a liquid, or a gas that can be made to lase. The second component
is a flash lamp or some other light energy source that puts
light into the active medium. The third component is a pair of mirrors
that are situated on both sides of the active medium and are designed
in such a way that one mirror transmits part of the energy
that strikes it, yielding the light beam that leaves the laser.
Lasers can produce energy because light is one of many forms of
energy that are called, collectively, electromagnetic radiation (among
the other forms of electromagnetic radiation are X rays and radio
waves). These forms of electromagnetic radiation have different wavelengths;
the smaller the wavelength, the higher the energy level. The
energy level is measured in units called “quanta.” The emission of
light quanta from atoms that are said to be in the “excited state” produces
energy, and the absorption of quanta by unexcited atoms—
atoms said to be in the “ground state”—excites those atoms.
The familiar light bulb spontaneously and haphazardly emits
light of many wavelengths from excited atoms. This emission occurs
in all directions and at widely varying times. In contrast, the
light reflection between the mirrors at the ends of a laser causes all
of the many excited atoms present in the active medium simultaneously
to emit light waves of the same wavelength. This process is
called “stimulated emission.”
Stimulated emission ultimately causes a laser to yield a beam of
coherent light, which means that the wavelength, emission time,
and direction of all the waves in the laser beam are the same. The
use of focusing devices makes it possible to convert an emitted laser
beam into a point source that can be as small as a few thousandths of
an inch in diameter. Such focused beams are very hot, and they can
be used for such diverse functions as cutting or welding metal objects
and performing delicate surgery. The nature of the active medium
used in a laser determines the wavelength of its emitted light
beam; this in turn dictates both the energy of the emitted quanta and
the appropriate uses for the laser.

474 / Laser vaporization
A blocked artery (top) can be threaded with a flexible fiber-optic fiber or bundle of fibers until
it reaches the blockage; the fiber then emits laser light, vaporizing the plaque (bottom) and
restoring circulation.
Maiman’s ruby laser, for example, has been used since the 1960’s
in eye surgery to reattach detached retinas. This is done by focusing
the laser on the tiny retinal tear that causes a retina to become detached.
The very hot, high-intensity light beam then “welds” the
retina back into place, bloodlessly, by burning it to produce scar tissue.
The burning process has no effect on nearby tissues. Other
types of lasers have been used in surgeries on the digestive tract and
the uterus since the 1970’s.
In 1983, a group of physicians began using lasers to treat cardiovascular
disease. The original work, which was carried out by a
number of physicians in Toulouse, France, involved the vaporization
of atheroma deposits (atherosclerotic plaque) in a human ar-

tery. This very exciting event added a new method to medical science’s
arsenal of life-saving techniques.
Consequences
Since their discovery, lasers have been used for many purposes
in science and industry. Such uses include the study of the laws of
chemistry and physics, photography, communications, and surveying.
Lasers have been utilized in surgery since the mid-1960’s, and
their use has had a tremendous impact on medicine. The first type
of laser surgery to be conducted was the repair of detached retinas
via ruby lasers. This technique has become the method of choice for
such eye surgery because it takes only minutes to perform rather
than the hours required for conventional surgical methods. It is also
beneficial because the lasing of the surgical site cauterizes that site,
preventing bleeding.
In the late 1970’s, the use of other lasers for abdominal cancer
surgery and uterine surgery began and flourished. In these
forms of surgery, more powerful lasers are used. In the 1980’s,
laser vaporization surgery (LVS) began to be used to clear atherosclerotic
plaque (atheromas) from clogged arteries. This methodology
gives cardiologists a useful new tool. Before LVS was
available, surgeons dislodged atheromas by means of “transluminal
angioplasty,” which involved pushing small, fluoroscopeguided
inflatable balloons through clogged arteries.
See also Blood transfusion; CAT scanner; Coronary artery bypass
surgery; Electrocardiogram; Laser; Laser eye surgery; Ultrasound.
Further Reading
Laser vaporization / 475
Fackelmann, Kathleen. “Internal Laser Blast Might Ease Heart
Pain.” USA Today (March 8, 1999).
Hecht, Jeff. Laser Pioneers. Rev. ed. Boston: Academic Press, 1992.
“Is Cervical Laser Therapy Painful?” Lancet no. 8629 (January 14,
1989).

476 / Laser vaporization
Lothian, Cheri L. “Laser Angioplasty: Vaporizing Coronary Artery
Plaque.” Nursing 22, no. 1 (January, 1992).
“New Cool Laser Procedure Has Promise for Treating Blocked Coronary
Arteries.” Wall Street Journal (May 15, 1989).
Rundle, Rhonda L. “FDA Approves Laser Systems for Angioplasty.”
Wall Street Journal (February 3, 1992).
Sutton, C. J. G., and Michael P. Diamond. Endoscopic Surgery for Gynecologists.
Philadelphia: W. B. Saunders, 1993.

Long-distance radiotelephony
Long-distance radiotelephony
The invention: The first radio transmissions from the United States
to Europe opened a new era in telecommunications.
The people behind the invention:
Guglielmo Marconi (1874-1937), Italian inventor of transatlantic
telegraphy
Reginald Aubrey Fessenden (1866-1932), an American radio
engineer
Lee de Forest (1873-1961), an American inventor
Harold D. Arnold (1883-1933), an American physicist
John J. Carty (1861-1932), an American electrical engineer
An Accidental Broadcast
477
The idea of commercial transatlantic communication was first
conceived by Italian physicist and inventor Guglielmo Marconi, the
pioneer of wireless telegraphy. Marconi used a spark transmitter to
generate radio waves that were interrupted, or modulated, to form
the dots and dashes of Morse code. The rapid generation of sparks
created an electromagnetic disturbance that sent radio waves of different
frequencies into the air—a broad, noisy transmission that was
difficult to tune and detect.
The inventor Reginald Aubrey Fessenden produced an alternative
method that became the basis of radio technology in the twentieth
century. His continuous radio waves kept to one frequency,
making them much easier to detect at long distances. Furthermore,
the continuous waves could be modulated by an audio signal, making
it possible to transmit the sound of speech.
Fessenden used an alternator to generate electromagnetic waves
at the high frequencies required in radio transmission. It was specially
constructed at the laboratories of the General Electric Company.
The machine was shipped to Brant Rock, Massachusetts, in
1906 for testing. Radio messages were sent to a boat cruising offshore,
and the feasibility of radiotelephony was thus demonstrated.
Fessenden followed this success with a broadcast of messages and

478 / Long-distance radiotelephony
music between Brant Rock and a receiving station constructed at
Plymouth, Massachusetts.
The equipment installed at Brant Rock had a range of about 160
kilometers. The transmission distance was determined by the strength
of the electric power delivered by the alternator, which was measured
in watts. Fessenden’s alternator was rated at 500 watts, but it
usually delivered much less power.
Yet this was sufficient to send a radio message across the Atlantic.
Fessenden had built a receiving station at Machrihanish, Scotland,
to test the operation of a large rotary spark transmitter that he
had constructed. An operator at this station picked up the voice of
an engineer at Brant Rock who was sending instructions to Plymouth.
Thus, the first radiotelephone message had been sent across
the Atlantic by accident. Fessenden, however, decided not to make
this startling development public. The station at Machrihanish was
destroyed in a storm, making it impossible to carry out further tests.
The successful transmission undoubtedly had been the result of exceptionally
clear atmospheric conditions that might never again favor
the inventor.
One of the parties following the development of the experiments
in radio telephony was the American Telephone and Telegraph
(AT&T) Company. Fessenden entered into negotiations to sell his
system to the telephone company, but, because of the financial panic
of 1907, the sale was never made.
Virginia to Paris and Hawaii
The English physicist John Ambrose Fleming had invented a twoelement
(diode) vacuum tube in 1904 that could be used to generate
and detect radio waves. Two years later, the American inventor Lee
de Forest added a third element to the diode to produce his “audion”
(triode), which was a more sensitive detector. John J. Carty, head of a
research and development effort at AT&T, examined these new devices
carefully. He became convinced that an electronic amplifier, incorporating
the triode into its design, could be used to increase the
strength of telephone signals and to long distances.
On Carty’s advice, AT&T purchased the rights to de Forest’s
audion. A team of about twenty-five researchers, under the leader-

Reginald Aubrey Fessenden
Long-distance radiotelephony / 479
Reginald Aubrey Fessenden was born in Canada in 1866 to
a small-town minister and his wife. After graduating from
Bishop’s College in Lennoxville, Quebec, he took a job as head
of Whitney Institute in Bermuda. However, he was brilliant and
volatile and had greater ambitions. After two years, he landed a
job as a tester for his idol, Thomas Edison. Soon he was working
as an engineer and chemist.
Fessenden became a professor of electrical engineering at
Purdue University in 1892 and then a year later at the University
of Pittsburgh. His ideas were often advanced, so far advanced
that some were not developed until much later, and by
others. His first patented invention, an electrolyte detector in
1900, was far more sensitive than others in use and made it possible
to pick up radio signals carrying complex sound. To transmit
such signals, he pioneered the use of carrier waves. During
his career he registered more than three hundred patents.
Suspicious and feisty, he also spent a lot of time in disputes,
and frequently in court, over his inventions. He sued his backers
at the National Electric Signaling Company over rights to
operate a connection to Great Britain, and won a $406,000 settlement,
which bankrupted the company. He sued Radio Corporation
of America (RCA) claiming it prevented him from exploiting
his own patents commercially. RCA settled out of court but
was enriched by Fessenden’s invention.
Having returned to Bermuda, Fessenden died in 1932. He
never succeeded in winning the fame and wealth for the radio
that he felt was due to him.
ship of physicist Harold D. Arnold, were assigned the job of perfecting
the triode and turning it into a reliable amplifier. The improved
triode was responsible for the success of transcontinental cable telephone
service, which was introduced in January, 1915. The triode
was also the basis of AT&T’s foray into radio telephony.
Carty’s research plan called for a system with three components:
an oscillator to generate the radio waves, a modulator to add the
audio signals to the waves, and an amplifier to transmit the radio
waves. The total power output of the system was 7,500 watts,
enough to send the radio waves over thousands of kilometers.

480 / Long-distance radiotelephony
The apparatus was installed in the U.S. Navy’s radio tower in
Arlington, Virginia, in 1915. Radio messages from Arlington were
picked up at a receiving station in California, a distance of 4,000 kilometers,
then at a station in Pearl Harbor, Hawaii, which was 7,200
kilometers from Arlington. AT&T’s engineers had succeeded in
joining the company telephone lines with the radio transmitter at
Arlington; therefore, the president of AT&T, Theodore Vail, could
pick up his telephone and talk directly with someone in California.
The next experiment was to send a radio message from Arlington
to a receiving station set up in the Eiffel Tower in Paris. After several
unsuccessful attempts, the telephone engineers in the Eiffel Tower
finally heard Arlington’s messages on October 21, 1915. The AT&T
receiving station in Hawaii also picked up the messages. The two receiving
stations had to send their reply by telegraph to the United
States because both stations were set up to receive only. Two-way
radio communication was still years in the future.
Impact
The announcement that messages had been received in Paris was
front-page news and brought about an outburst of national pride in
the United States. The demonstration of transatlantic radio telephony
was more important as publicity for AT&T than as a scientific
advance. All the credit went to AT&T and to Carty’s laboratory.
Both Fessenden and de Forest attempted to draw attention to their
contributions to long-distance radio telephony, but to no avail. The
Arlington-to-Paris transmission was a triumph for corporate public
relations and corporate research.
The development of the triode had been achieved with large
teams of highly trained scientists—in contrast to the small-scale efforts
of Fessenden and de Forest, who had little formal scientific
training. Carty’s laboratory was an example of the new type of industrial
research that was to dominate the twentieth century. The
golden days of the lone inventor, in the mold of Thomas Edison or
Alexander Graham Bell, were gone.
In the years that followed the first transatlantic radio telephone
messages, little was done by AT&T to advance the technology or to
develop a commercial service. The equipment used in the 1915 dem-

onstration was more a makeshift laboratory apparatus than a prototype
for a new radio technology. The messages sent were short and
faint. There was a great gulf between hearing “hello” and “goodbye”
amid the static. The many predictions of a direct telephone
connection between New York and other major cities overseas were
premature. It was not until 1927 that a transatlantic radio circuit was
opened for public use. By that time, a new technological direction
had been taken, and the method used in 1915 had been superseded
by shortwave radio communication.
See also Communications satellite; Internet; Long-distance telephone;
Radio; Radio crystal sets; Radiotelephony; Television.
Further Reading
Long-distance radiotelephony / 481
Marconi, Degna. My Father: Marconi. Toronto: Guernica Editions,
1996.
Masini, Giancarlo. Marconi. New York: Marsilio, 1995.
Seitz, Frederick. The Cosmic Inventor: Reginald Aubrey Fessenden.
Philadelphia: American Philosophical Society, 1999.
Streissguth, Thomas. Communications: Sending the Message. Minneapolis,
Minn.: Oliver Press, 1997.

482
Long-distance telephone
Long-distance telephone
The invention: System for conveying voice signals via wires over
long distances.
The people behind the invention:
Alexander Graham Bell (1847-1922), a Scottish American
inventor
Thomas A. Watson (1854-1934), an American electrical engineer
The Problem of Distance
The telephone may be the most important invention of the nineteenth
century. The device developed by Alexander Graham Bell
and Thomas A. Watson opened a new era in communication and
made it possible for people to converse over long distances for the
first time. During the last two decades of the nineteenth century and
the first decade of the twentieth century, the American Telephone
and Telegraph (AT&T) Company continued to refine and upgrade
telephone facilities, introducing such innovations as automatic dialing
and long-distance service.
One of the greatest challenges faced by Bell engineers was to
develop a way of maintaining signal quality over long distances.
Telephone wires were susceptible to interference from electrical
storms and other natural phenomena, and electrical resistance
and radiation caused a fairly rapid drop-off in signal strength,
which made long-distance conversations barely audible or unintelligible.
By 1900, Bell engineers had discovered that signal strength could
be improved somewhat by wrapping the main wire conductor with
thinner wires called “loading coils” at prescribed intervals along
the length of the cable. Using this procedure, Bell extended longdistance
service from New York to Denver, Colorado, which was
then considered the farthest point that could be reached with acceptable
quality. The result, however, was still unsatisfactory, and
Bell engineers realized that some form of signal amplification would
be necessary to improve the quality of the signal.

A breakthrough came in 1906, when Lee de Forest invented the
“audion tube,” which could send and amplify radio waves. Bell scientists
immediately recognized the potential of the new device for
long-distance telephony and began building amplifiers that would
be placed strategically along the long-distance wire network.
Work progressed so quickly that by 1909, Bell officials were predicting
that the first transcontinental long-distance telephone service,
between New York and San Francisco, was imminent. In that
year, Bell president Theodore N. Vail went so far as to promise the
organizers of the Panama-Pacific Exposition, scheduled to open in
San Francisco in 1914, that Bell would offer a demonstration at
the exposition. The promise was risky, because certain technical
problems associated with sending a telephone signal over a 4,800kilometer
wire had not yet been solved. De Forest’s audion tube was
a crude device, but progress was being made.
Two more breakthroughs came in 1912, when de Forest improved
on his original concept and Bell engineer Harold D. Arnold
improved it further. Bell bought the rights to de Forest’s vacuumtube
patents in 1913 and completed the construction of the New
York-San Francisco circuit. The last connection was made at the
Utah-Nevada border on June 17, 1914.
Success Leads to Further Improvements
Long-distance telephone / 483
Bell’s long-distance network was tested successfully on June 29,
1914, but the official demonstration was postponed until January
25, 1915, to accommodate the Panama-Pacific Exposition, which
had also been postponed. On that date, a connection was established
between Jekyll Island, Georgia, where Theodore Vail was recuperating
from an illness, and New York City, where Alexander
Graham Bell was standing by to talk to his former associate Thomas
Watson, who was in San Francisco. When everything was in place,
the following conversation took place. Bell: “Hoy! Hoy! Mr. Watson?
Are you there? Do you hear me?” Watson: “Yes, Dr. Bell, I hear
you perfectly. Do you hear me well?” Bell: “Yes, your voice is perfectly
distinct. It is as clear as if you were here in New York.”
The first transcontinental telephone conversation transmitted
by wire was followed quickly by another that was transmitted via

484 / Long-distance telephone
radio. Although the Bell company was slow to recognize the potential
of radio wave amplification for the “wireless” transmission
of telephone conversations, by 1909 the company had made a significant
commitment to conduct research in radio telephony. On
April 4, 1915, a wireless signal was transmitted by Bell technicians
from Montauk Point on Long Island, New York, to Wilmington,
Delaware, a distance of more than 320 kilometers. Shortly thereafter,
a similar test was conducted between New York City and
Brunswick, Georgia, via a relay station at Montauk Point. The total
distance of the transmission was more than 1,600 kilometers. Finally,
in September, 1915, Vail placed a successful transcontinental radiotelephone
call from his office in New York to Bell engineering chief
J. J. Carty in San Francisco.
Only a month later, the first telephone transmission across the
Atlantic Ocean was accomplished via radio from Arlington, Virginia,
to the Eiffel Tower in Paris, France. The signal was detectable,
although its quality was poor. It would be ten years before true
transatlantic radio-telephone service would begin.
The Bell company recognized that creating a nationwide longdistance
network would increase the volume of telephone calls simply
by increasing the number of destinations that could be reached
from any single telephone station. As the network expanded, each
subscriber would have more reason to use the telephone more often,
thereby increasing Bell’s revenues. Thus, the company’s strategy
became one of tying local and regional networks together to create
one large system.
Impact
Just as the railroads had interconnected centers of commerce, industry,
and agriculture all across the continental United States in the
nineteenth century, the telephone promised to bring a new kind of
interconnection to the country in the twentieth century: instantaneous
voice communication. During the first quarter century after
the invention of the telephone and during its subsequent commercialization,
the emphasis of telephone companies was to set up central
office switches that would provide interconnections among
subscribers within a fairly limited geographical area. Large cities

were wired quickly, and by the beginning of the twentieth century
most were served by telephone switches that could accommodate
thousands of subscribers.
The development of intercontinental telephone service was a
milestone in the history of telephony for two reasons. First, it was a
practical demonstration of the almost limitless applications of this
innovative technology. Second, for the first time in its brief history,
the telephone network took on a national character. It became clear
that large central office networks, even in large cities such as New
York, Chicago, and Baltimore, were merely small parts of a much
larger, universally accessible communication network that spanned
a continent. The next step would be to look abroad, to Europe and
beyond.
See also Cell phone; Fax machine; Internet; Long-distance radiotelephony;
Rotary dial telephone; Telephone switching; Touch-tone
telephone.
Further Reading
Long-distance telephone / 485
Coe, Lewis. The Telephone and Its Several Inventors: A History. Jefferson,
N.C.: McFarland, 1995.
Mackay, James A. Alexander Graham Bell: A Life. New York: J. Wiley,
1997.
Young, Peter. Person to Person: The International Impact of the Telephone.
Cambridge: Granta Editions, 1991.

486
Mammography
Mammography
The invention: The first X-ray procedure for detecting and diagnosing
breast cancer.
The people behind the invention:
Albert Salomon, the first researcher to use X-ray technology
instead of surgery to identify breast cancer
Jacob Gershon-Cohen (1899-1971), a breast cancer researcher
Studying Breast Cancer
Medical researchers have been studying breast cancer for more
than a century. At the end of the nineteenth century, however, no one
knew how to detect breast cancer until it was quite advanced. Often,
by the time it was detected, it was too late for surgery; many patients
who did have surgery died. So after X-ray technology first appeared
in 1896, cancer researchers were eager to experiment with it.
The first scientist to use X-ray techniques in breast cancer experiments
was Albert Salomon, a German surgeon. Trying to develop a
biopsy technique that could tell which tumors were cancerous and
thereby avoid unnecessary surgery, he X-rayed more than three
thousand breasts that had been removed from patients during breast
cancer surgery. In 1913, he published the results of his experiments,
showing that X rays could detect breast cancer. Different types of Xray
images, he said, showed different types of cancer.
Though Salomon is recognized as the inventor of breast radiology,
he never actually used his technique to diagnose breast cancer.
In fact, breast cancer radiology, which came to be known as “mammography,”
was not taken up quickly by other medical researchers.
Those who did try to reproduce his research often found that their
results were not conclusive.
During the 1920’s, however, more research was conducted in Leipzig,
Germany, and in South America. Eventually, the Leipzig researchers,
led by Erwin Payr, began to use mammography to diagnose
cancer. In the 1930’s, a Leipzig researcher named W. Vogel
published a paper that accurately described differences between
cancerous and noncancerous tumors as they appeared on X-ray pho-

tographs. Researchers in the United States paid little attention to
mammography until 1926. That year, a physician in Rochester, New
York, was using a fluoroscope to examine heart muscle in a patient
and discovered that the fluoroscope could be used to make images of
breast tissue as well. The physician, Stafford L. Warren, then developed
a stereoscopic technique that he used in examinations before
surgery. Warren published his findings in 1930; his article also described
changes in breast tissue that occurred because of pregnancy,
lactation (milk production), menstruation, and breast disease. Yet
Stafford’s technique was complicated and required equipment that
most physicians of the time did not have. Eventually, he lost interest
in mammography and went on to other research.
Using the Technique
Mammography / 487
In the late 1930’s, Jacob Gershon-Cohen became the first clinician
to advocate regular mammography for all women to detect breast
cancer before it became a major problem. Mammography was not
very expensive, he pointed out, and it was already quite accurate. A
milestone in breast cancer research came in 1956, when Gershon-
Cohen and others began a five-year study of more than 1,300 women
to test the accuracy of mammography for detecting breast cancer.
Each woman studied was screened once every six months. Of the
1,055 women who finished the study, 92 were diagnosed with benign
tumors and 23 with malignant tumors. Remarkably, out of all
these, only one diagnosis turned out to be wrong.
During the same period, Robert Egan of Houston began tracking
breast cancer X rays. Over a span of three years, one thousand X-ray
photographs were used to make diagnoses. When these diagnoses
were compared to the results of surgical biopsies, it was confirmed
that mammography had produced 238 correct diagnoses of cancer,
out of 240 cases. Egan therefore joined the crusade for regular breast
cancer screening.
Once mammography was finally accepted by doctors in the late
1950’s and early 1960’s, researchers realized that they needed a way
to teach mammography quickly and effectively to those who would
use it. A study was done, and it showed that any radiologist could
conduct the procedure with only five days of training.

488 / Mammography
In the early 1970’s, the American Cancer Society and the National
Cancer Institute joined forces on a nationwide breast cancer
screening program called the “Breast Cancer Detection Demonstration
Project.” Its goal in 1971 was to screen more than 250,000
women over the age of thirty-five.
Since the 1960’s, however, some people had argued that mammography
was dangerous because it used radiation on patients. In
1976, Ralph Nader, a consumer advocate, stated that women who
were to undergo mammography should be given consent forms
that would list the dangers of radiation. In the years that followed,
mammography was refined to reduced the amount of radiation
needed to detect cancer. It became a standard tool for diagnosis, and
doctors recommended that women have a mammogram every two
or three years after the age of forty.
Impact
Radiology is not a science that concerns only breast cancer screening.
While it does provide the technical facilities necessary to practice
mammography, the photographic images obtained must be interpreted
by general practitioners, as well as by specialists. Once
Physicians recommend that women have a mammogram every two or three years after the
age of forty. (Digital Stock)

Gershon-Cohen had demonstrated the viability of the technique, a
means of training was devised that made it fairly easy for clinicians
to learn how to practice mammography successfully. Once all these
factors—accuracy, safety, simplicity—were in place, mammography
became an important factor in the fight against breast cancer.
The progress made in mammography during the twentieth century
was a major improvement in the effort to keep more women
from dying of breast cancer. The disease has always been one of the
primary contributors to the number of female cancer deaths that occur
annually in the United States and around the world. This high
figure stems from the fact that women had no way of detecting the
disease until tumors were in an advanced state.
Once Salomon’s procedure was utilized, physicians had a means
by which they could look inside breast tissue without engaging in
exploratory surgery, thus giving women a screening technique that
was simple and inexpensive. By 1971, a quarter million women over
age thirty-five had been screened. Twenty years later, that number
was in the millions.
See also Amniocentesis; CAT scanner; Electrocardiogram; Electroencephalogram;
Holography; Nuclear magnetic resonance; Pap
test; Syphilis test; Ultrasound.
Further Reading
Mammography / 489
“First Digital Mammography System Approved by FDA.” FDA
Consumer 34, no. 3 (May/June, 2000).
Hindle, William H. Breast Care: A Clinical Guidebook for Women’s Primary
Health Care Providers. New York: Springer, 1999.
Okie, Susan. “More Women Are Getting Mammograms: Experts
Agree That the Test Has Played Big Role in Reducing Deaths
from Breast Cancer.” Washington Post (January 21, 1997).
Wolbarst, Anthony B. Looking Within: How X-ray, CT, MRI, Ultrasound,
and Other Medical Images Are Created, and How They Help
Physicians Save Lives. Berkeley: University of California Press,
1999.

490
Mark I calculator
Mark I calculator
The invention: Early digital calculator designed to solve differential
equations that was a forerunner of modern computers.
The people behind the invention:
Howard H. Aiken (1900-1973), Harvard University professor
and architect of the Mark I
Clair D. Lake (1888-1958), a senior engineer at IBM
Francis E. Hamilton (1898-1972), an IBM engineer
Benjamin M. Durfee (1897-1980), an IBM engineer
The Human Computer
The physical world can be described by means of mathematics.
In principle, one can accurately describe nature down to the smallest
detail. In practice, however, this is impossible except for the simplest
of atoms. Over the years, physicists have had great success in
creating simplified models of real physical processes whose behavior
can be described by the branch of mathematics called “calculus.”
Calculus relates quantities that change over a period of time. The
equations that relate such quantities are called “differential equations,”
and they can be solved precisely in order to yield information
about those quantities. Most natural phenomena, however, can
be described only by differential equations that can be solved only
approximately. These equations are solved by numerical means that
involve performing a tremendous number of simple arithmetic operations
(repeated additions and multiplications). It has been the
dream of many scientists since the late 1700’s to find a way to automate
the process of solving these equations.
In the early 1900’s, people who spent day after day performing the
tedious operations that were required to solve differential equations
were known as “computers.” During the two world wars, these human
computers created ballistics tables by solving the differential
equations that described the hurling of projectiles and the dropping
of bombs from aircraft. The war effort was largely responsible for accelerating
the push to automate the solution to these problems.

A Computational Behemoth
Mark I calculator / 491
The ten-year period from 1935 to 1945 can be considered the
prehistory of the development of the digital computer. (In a digital
computer, digits represent magnitudes of physical quantities.
These digits can have only certain values.) Before this time, all
machines for automatic calculation were either analog in nature
(in which case, physical quantities such as current or voltage represent
the numerical values of the equation and can vary in a continuous
fashion) or were simplistic mechanical or electromechanical
adding machines.
This was the situation that faced Howard Aiken. At the time, he
was a graduate student working on his doctorate in physics. His
dislike for the tremendous effort required to solve the differential
equations used in his thesis drove him to propose, in the fall of 1937,
constructing a machine that would automate the process. He proposed
taking existing business machines that were commonly used
in accounting firms and combining them into one machine that
would be controlled by a series of instructions. One goal was to
eliminate all manual intervention in the process in order to maximize
the speed of the calculation.
Aiken’s proposal came to the attention of Thomas Watson, who
was then the president of International Business Machines Corporation
(IBM). At that time, IBM was a major supplier of business machines
and did not see much of a future in such “specialized” machines.
It was the pressure provided by the computational needs of
the military in World War II that led IBM to invest in building automated
calculators. In 1939, a contract was signed in which IBM
agreed to use its resources (personnel, equipment, and finances) to
build a machine for Howard Aiken and Harvard University.
IBM brought together a team of seasoned engineers to fashion a
working device from Aiken’s sketchy ideas. Clair D. Lake, who was
selected to manage the project, called on two talented engineers—
Francis E. Hamilton and Benjamin M. Durfee—to assist him.
After four years of effort, which was interrupted at times by the
demands of the war, a machine was constructed that worked remarkably
well. Completed in January, 1943, at Endicott, New York,
it was then disassembled and moved to Harvard University in Cam-

492 / Mark I calculator
bridge, Massachusetts, where it was reassembled. Known as the IBM
automatic sequence controlled calculator (ASCC), it began operation
in the spring of 1944 and was formally dedicated and revealed to the
public on August 7, 1944. Its name indicates the machine’s distinguishing
feature: the ability to load automatically the instructions
that control the sequence of the calculation. This capability was provided
by punching holes, representing the instructions, in a long,
ribbonlike paper tape that could be read by the machine.
Computers of that era were big, and the ASCC I was particularly
impressive. It was 51 feet long by 8 feet tall, and it weighed 5 tons. It
contained more than 750,000 parts, and when it was running, it
sounded like a room filled with sewing machines. The ASCC later
became known as the Harvard Mark I.
Impact
Although this machine represented a significant technological
achievement at the time and contributed ideas that would be used
in subsequent machines, it was almost obsolete from the start. It was
electromechanical, since it relied on relays, but it was built at the
dawn of the electronic age. Fully electronic computers offered better
reliability and faster speeds. Howard Aiken continued, without the
help of IBM, to develop successors to the Mark I. Because he resisted
using electronics, however, his machines did not significantly affect
the direction of computer development.
For all its complexity, the Mark I operated reasonably well, first
solving problems related to the war effort and then turning its attention
to the more mundane tasks of producing specialized mathematical
tables. It remained in operation at the Harvard Computational
Laboratory until 1959, when it was retired and disassembled.
Parts of this landmark computational tool are now kept at the
Smithsonian Institute.
See also BASIC programming language; Differential analyzer;
Personal computer; Pocket calculator; UNIVAC computer.

Further Reading
Mark I calculator / 493
Cohen, I. Bernard. Howard Aiken: Portrait of a Computer Pioneer. Cambridge,
Mass.: MIT Press, 1999.
Ritchie, David. The Computer Pioneers: The Making of the Modern Computer.
New York: Simon and Schuster, 1986.
Slater, Robert. Portraits in Silicon. Cambridge, Mass.: MIT Press,
1987.

494
Mass spectrograph
Mass spectrograph
The invention: The first device used to measure the mass of atoms,
which was found to be the result of the combination of isotopes.
The people behind the invention:
Francis William Aston (1877-1945), an English physicist who
was awarded the 1922 Nobel Prize in Chemistry
Sir Joseph John Thomson (1856-1940), an English physicist
William Prout (1785-1850), an English biochemist
Ernest Rutherford (1871-1937), an English physicist
Same Element, Different Weights
Isotopes are different forms of a chemical element that act similarly
in chemical or physical reactions. Isotopes differ in two ways:
They possess different atomic weights and different radioactive transformations.
In 1803, John Dalton proposed a new atomic theory of
chemistry that claimed that chemical elements in a compound combine
by weight in whole number proportions to one another. By 1815,
William Prout had taken Dalton’s hypothesis one step further and
claimed that the atomic weights of elements were integral (the integers
are the positive and negative whole numbers and zero) multiples
of the hydrogen atom. For example, if the weight of hydrogen
was 1, then the weight of carbon was 12, and that of oxygen 16. Over
the next decade, several carefully controlled experiments were conducted
to determine the atomic weights of a number of elements. Unfortunately,
the results of these experiments did not support Prout’s
hypothesis. For example, the atomic weight of chlorine was found to
be 35.5. It took a theory of isotopes, developed in the early part of the
twentieth century, to verify Prout’s original theory.
After his discovery of the electron, Sir Joseph John Thomson, the
leading physicist at the Cavendish Laboratory in Cambridge, England,
devoted much of his remaining research years to determining
the nature of “positive electricity.” (Since electrons are negatively
charged, most electricity is negative.) While developing an instrument
sensitive enough to analyze the positive electron, Thomson in-

vited Francis William Aston to work with him at the Cavendish Laboratory.
Recommended by J. H. Poynting, who had taught Aston
physics at Mason College, Aston began a lifelong association at
Cavendish, and Trinity College became his home.
When electrons are stripped from an atom, the atom becomes positively
charged. Through the use of magnetic and electrical fields, it is
possible to channel the resulting positive rays into parabolic tracks.
By examining photographic plates of these tracks, Thomson was able
to identify the atoms of different elements. Aston’s first contribution
at Cavendish was to improve the instrument used to photograph
the parabolic tracks. He developed a more efficient pump to
create the required vacuum and devised a camera that would provide
sharper photographs. By 1912, the improved apparatus had
provided proof that the individual molecules of a substance have
the same mass. While working on the element neon, however,
Thomson obtained two parabolas, one with a mass of 20 and the
other with a mass of 22, which seemed to contradict the previous
findings that molecules of any substance have the same mass. Aston
was given the task of resolving this mystery.
Treating Particles Like Light
Mass spectrograph / 495
In 1919, Aston began to build a device called a “mass spectrograph.”
The idea was to treat ionized or positive atoms like light. He
reasoned that, because light can be dispersed into a rainbowlike
spectrum and analyzed by means of its different colors, the same
procedure could be used with atoms of an element such as neon. By
creating a device that used magnetic fields to focus the stream of
particles emitted by neon, he was able to create a mass spectrum
and record it on a photographic plate. The heavier mass of neon (the
first neon isotope) was collected on one part of a spectrum and the
lighter neon (the second neon isotope) showed up on another. This
mass spectrograph was a magnificent apparatus: The masses could
be analyzed without reference to the velocity of the particles, which
was a problem with the parabola method devised by Thomson.
Neon possessed two isotopes: one with a mass of 20 and the other
with a mass of 22, in a ratio of 10:1. When combined, this gave the
atomic weight 20.20, which was the accepted weight of neon.

496 / Mass spectrograph
Francis William Aston
Francis W. Aston was born near Birmingham, England, in
1877 to William Aston, a farmer and metals dealer, and Fanny
Charlotte Hollis, a gunmaker’s daughter. As a boy he loved to
perform experiments by himself in his own small laboratory at
home. His diligence helped him earn top marks in school, and
he attended Mason College (later the University of Birmingham).
However, he failed to win a scholarship to continue his
studies after graduation in 1901.
He did not give up on experiments, however, even while
holding a job as the chemist for a local brewery. He built his own
equipment and investigated the nature of electricity. This work
attracted the attention of the most famous researchers of the
day. He finally got a scholarship in 1903 to the University of Birmingham
and then joined the staff of Joseph John Thomson at
the Royal Institution in London and Cambridge University,
which remained his home until his death in 1945.
Aston liked to work alone as much as possible. Given his
unflagging attention to the details of measurement and his inventiveness
with experimental equipment, his colleagues respected
his lone-dog approach. Their trust was rewarded. After
refining the mass spectrograph, Aston was able to explain a
thorny problem in chemistry by showing that elements are
composed of differing percentages of isotopes and that atomic
weight varied slightly depending on the density of their atoms’
nuclei. The research earned him the Nobel Prize in Chemistry in
1922.
Aston’s solitude extended into his private life. He never
married, lavishing his affection instead on animals, outdoor
sports, photography, travel, and music.
Aston’s accomplishment in developing the mass spectrograph
was recognized immediately by the scientific community. His was a
simple device that was capable of accomplishing a large amount of
research quickly. The field of isotope research, which had been
opened up by Aston’s research, ultimately played an important part
in other areas of physics.

Impact
The years following 1919 were highly charged with excitement,
since month after month new isotopes were announced. Chlorine
had two; bromine had isotopes of 79 and 81, which gave an almost
exact atomic weight of 80; krypton had six isotopes; and xenon had
even more. In addition to the discovery of nonradioactive isotopes,
the “whole-number rule” for chemistry was verified: Protons were
the basic building blocks for different atoms, and they occurred exclusively
in whole numbers.
Aston’s original mass spectrograph had an accuracy of 1 in 1,000.
In 1927, he built an even more accurate instrument, which was ten
times more accurate. The new apparatus was sensitive enough to
measure Albert Einstein’s law of mass energy conversion during a
nuclear reaction. Between 1927 and 1935, Aston reviewed all the elements
that he had worked on earlier and published updated results.
He also began to build a still more accurate instrument, which
proved to be of great value to nuclear chemistry.
The discovery of isotopes opened the way to further research in
nuclear physics and completed the speculations begun by Prout
during the previous century. Although radioactivity was discovered
separately, isotopes played a central role in the field of nuclear
physics and chain reactions.
See also Cyclotron; Electron microscope; Neutrino detector;
Scanning tunneling microscope; Synchrocyclotron; Tevatron accelerator;
Ultramicroscope.
Further Reading
Mass spectrograph / 497
Aston, Francis William. “Mass Spectra and Isotopes” [Nobel lecture].
In Chemistry, 1922-1941. River Edge, N.J.: World Scientific,
1999.
Squires, Gordon. “Francis Aston and the Mass Spectrograph.” Journal
of the Chemical Society. Dalton Transactions no. 23 (1998).
Thackray, Arnold. Atoms and Powers: An Essay on Newtonian Matter-
Theory and the Development of Chemistry. Cambridge, Mass.: Harvard
University Press, 1970.

498
Memory metal
Memory metal
The invention: Known as nitinol, a metal alloy that returns to its
original shape, after being deformed, when it is heated to the
proper temperature.
The person behind the invention:
William Buehler (1923- ), an American metallurgist
The Alloy with a Memory
In 1960, William Buehler developed an alloy that consisted of 53
to 57 percent nickel (by weight) and the balance titanium. This alloy,
which is called nitinol, turned out to have remarkable properties.
Nitinol is a “memory metal,” which means that, given the proper
conditions, objects made of nitinol can be restored to their original
shapes even after they have been radically deformed. The return to
the original shape is triggered by heating the alloy to a moderate
temperature. As the metal “snaps back” to its original shape, considerable
force is exerted and mechanical work can be done.
Alloys made of nickel and titanium have great potential in a
wide variety of industrial and government applications. These include:
for the computer market, a series of high-performance electronic
connectors; for the medical market, intravenous fluid devices
that feature precise fluid control; for the consumer market, eyeglass
frame components; and, for the industrial market, power cable couplings
that provide durability at welded joints.
The Uncoiling Spring
At one time, the “uncoiling spring experiment” was used to
amuse audiences, and a number of scientists have had fun with
nitinol in front of unsuspecting viewers. It is now generally recognized
that the shape memory effect involves a thermoelastic transformation
at the atomic level. This process is unique in that the
transformation back to the original shape occurs as a result of stored
elastic energy that assists the chemical driving force that is unleashed
by heating the metal.

Memory metal / 499
The mechanism, simply stated, is that shape memory alloys
are rather easily deformed below their “critical temperature.”
Provided that the extent of the deformation is not too great, the
original, undeformed state can be recovered by heating the alloy
to a temperature just below the critical temperature. It is also
significant that substantial stresses are generated when a deformed
specimen “springs back” to its original shape. This phenomenon
is very peculiar compared to the ordinary behavior of
most materials.
Researchers at the Naval Ordnance Laboratory discovered nitinol
by accident in the process of trying to learn how to make titanium
less brittle. They tried adding nickel, and when they were showing a
wire of the alloy to some administrators, someone smoking a cigar
held his match too close to the sample, causing the nitinol to spring
back into shape. One of the first applications of the discovery was a
new way to link hydraulic lines on the Navy’s F-14 fighter jets. The
nitinol “sleeve” was cooled with liquid nitrogen, which enlarged
the sample. Then it was slipped into place between two pipes.
When the sleeve was warmed up, it contracted, clamping the pipes
together and keeping them clamped with a force of nearly 50,000
pounds per square inch.
Nitinol is not an easy alloy with which to work. When it is drilled
or passed through a lathe, it becomes hardened and resists change.
Welding nitinol and electroplating it have become manufacturing
nightmares. It also resists taking on a desired shape. The frictional
forces of many processes heat the nitinol, which activates its memory.
Its fantastic elasticity also causes difficulties. If it is placed in a press
with too little force, the spring comes out of the die unchanged. With
too much force, the metal breaks into fragments. Using oil as a cooling
lubricant and taking a step-wise approach to altering the alloy,
however, allows it to be fashioned into particular shapes.
One unique use of nitinol occurs in cardiac surgery. Surgical
tools made of nitinol can be bent up to 90 degrees, allowing them
to be passed into narrow vessels and then retrieved. The tools are
then straightened out in an autoclave so that they can be reused.

500 / Memory metal
Consequences
Many of the technical problems of working with nitinol have
been solved, and manufacturers of the alloy are selling more than
twenty different nitinol products to countless companies in the
fields of medicine, transportation, consumer products, and toys.
Nitinol toys include blinking movie posters, butterflies with
flapping wings, and dinosaurs whose tails move; all these applications
are driven by a contracting bit of wire that is connected to a
watch battery. The “Thermobile” and the “Icemobile” are toys whose
wheels are set in motion by hot water or by ice cubes.
Orthodontists sometimes use nitinol wires and springs in braces
because the alloy pulls with a force that is more gentle and even
than that of stainless steel, thus causing less pain. Nitinol does not
react with organic materials, and it is also useful as a new type of
blood-clot filter. Best of all, however, is the use of nitinol for eyeglass
frames. If the wearer deforms the frames by sitting on them (and
people do so frequently), the optometrist simply dips the crumpled
frames in hot water and the frames regain their original shape.
From its beginnings as an “accidental” discovery, nitinol has
gone on to affect various fields of science and technology, from the
“Cryofit” couplings used in the hydraulic tubing of aircraft to the
pin-and-socket contacts used in electrical circuits. Nitinol has also
found its way into integrated circuit packages.
In an age of energy conservation, the unique phase transformation
of nickel-titanium alloys allows them to be used in lowtemperature
heat engines. The world has abundant resources of
low-grade thermal energy, and the recovery of this energy can be
accomplished by the use of materials such as nitinol. Despite the
limitations imposed on heat engines working at low temperatures
across a small temperature change, sources of low-grade heat are
so widespread that the economical conversion of a fractional percentage
of that energy could have a significant impact on the
world’s energy supply.
Nitinol has also become useful as a material capable of absorbing
internal vibrations in structural materials, and it has been used as
“Harrington rods” to treat scoliosis (curvature of the spine).

See also Disposable razor; Neoprene; Plastic; Steelmaking process;
Teflon; Tungsten filament.
Further Reading
Memory metal / 501
Gisser, Kathleen R. C., et al. “Nickel-Titanium Memory Metal.” Journal
of Chemical Education 71, no. 4 (April, 1994).
Iovine, John. “The World’s ‘Smartest’ Metal.” Poptronics 1, no. 12
(December, 2000).
Jackson, Curtis M., H. J. Wagner, and Roman Jerzy Wasilewski. 55-
Nitinol: The Alloy with a Memory: Its Physical Metallurgy, Properties,
and Applications. Washington: Technology Utilization Office,
1972.
Walker, Jearl. “The Amateur Scientist.” Scientific American 254, no. 5
(May, 1986).

502
Microwave cooking
Microwave cooking
The invention: System of high-speed cooking that uses microwave
radition to agitate liquid molecules to raise temperatures by friction.
The people behind the invention:
Percy L. Spencer (1894-1970), an American engineer
Heinrich Hertz (1857-1894), a German physicist
James Clerk Maxwell (1831-1879), a Scottish physicist
The Nature of Microwaves
Microwaves are electromagnetic waves, as are radio waves, X
rays, and visible light. Water waves and sound waves are waveshaped
disturbances of particles in the media—water in the case of
water waves and air or water in the case of sound waves—through
which they travel. Electromagnetic waves, however, are wavelike
variations of intensity in electric and magnetic fields.
Electromagnetic waves were first studied in 1864 by James Clerk
Maxwell, who explained mathematically their behavior and velocity.
Electromagnetic waves are described in terms of their “wavelength”
and “frequency.” The wavelength is the length of one cycle,
which is the distance from the highest point of one wave to the highest
point of the next wave, and the frequency is the number of cycles
that occur in one second. Frequency is measured in units called
“hertz,” named for the German physicist Heinrich Hertz. The frequencies
of microwaves run from 300 to 3,000 megahertz (1 megahertz
equals 1 million hertz, or 1 million cycles per second), corresponding
to wavelengths of 100 to 10 centimeters.
Microwaves travel in the same way that light waves do; they are
reflected by metallic objects, absorbed by some materials, and transmitted
by other materials. When food is subjected to microwaves, it
heats up because the microwaves make the water molecules in foods
(water is the most common compound in foods) vibrate. Water is a
“dipole molecule,” which means that it contains both positive and
negative charges. When the food is subjected to microwaves, the di-

pole water molecules try to align themselves with the alternating
electromagnetic field of the microwaves. This causes the water molecules
to collide with one another and with other molecules in the
food. Consequently, heat is produced as a result of friction.
Development of the Microwave Oven
Microwave cooking / 503
Percy L. Spencer apparently discovered the principle of microwave
cooking while he was experimenting with a radar device at
the Raytheon Company. A candy bar in his pocket melted after being
exposed to microwaves. After realizing what had happened,
Spencer made the first microwave oven from a milk can and applied
for two patents, “Method of Treating Foodstuffs” and “Means for
Treating Foodstuffs,” on October 8, 1945, giving birth to microwaveoven
technology.
Spencer wrote that his invention “relates to the treatment of
foodstuffs and, more particularly, to the cooking thereof through
the use of electromagnetic energy.” Though the use of electromagnetic
energy for heating was recognized at that time, the frequencies
that were used were lower than 50 megahertz. Spencer discovered
that heating at such low frequencies takes a long time. He eliminated
the time disadvantage by using shorter wavelengths in the
microwave region. Wavelengths of 10 centimeters or shorter were
comparable to the average dimensions of foods. When these wavelengths
were used, the heat that was generated became intense, the
energy that was required was minimal, and the process became efficient
enough to be exploited commercially.
Although Spencer’s patents refer to the cooking of foods with
microwave energy, neither deals directly with a microwave oven.
The actual basis for a microwave oven may be patents filed by other
researchers at Raytheon. A patent by Karl Stiefel in 1949 may be the
forerunner of the microwave oven, and in 1950, Fritz Gross received
a patent entitled “Cooking Apparatus,” which specifically describes
an oven that is very similar to modern microwave ovens.
Perhaps the first mention of a commercial microwave oven was
made in the November, 1946, issue of Electronics magazine. This article
described the newly developed Radarange as a device that
could bake biscuits in 29 seconds, cook hamburgers in 35 seconds,

504 / Microwave cooking
Percy L. Spencer
Percy L. Spencer (1894-1970) had an unpromising background
for the inventor of the twentieth century’s principal innovation
in the technology of cooking. He was orphaned while
still a young boy and never completed grade school. However,
he possessed a keen curiosity and the imaginative intelligence
to educate himself and recognize how to make things better.
In 1941 the magnetron, which produces microwaves, was so
complex and difficult to make that fewer than two dozen were
produced in a day. This pace delayed the campaign to improve
radar, which used magnetrons, so Spencer, while working for
Raytheon Corporation, set out to speed things along. He simplified
the design and made it more efficient at the same time. Production
of magnetrons soon increased more than a thousandfold.
In 1945 he discovered by accident that microwaves could
heat chocolate past the melting point. He immediately tried an
experiment by training microwaves on popcorn kernels and
was delighted to see them puff up straight away.
The first microwave oven based on his discovery stood five
feet, six inches tall and weighed 750 pounds, suitable only for
restaurants. However, it soon got smaller, thanks to researchers
at Raytheon. And after some initial hostility from cooks, it became
popular. Raytheon bought Amana Refrigeration in 1965
to manufacture the home models and marketed them worldwide.
Meanwhile, Spencer had become a senior vice president
at the company and a member of its board of directors. Raytheon
named one of its buildings after him, the U.S. Navy presented
him with the Distinguished Service Medal for his contributions,
and in 1999 he entered the Inventors Hall of Fame.
and grill a hot dog in 8 to 10 seconds. Another article that appeared a
month later mentioned a unit that had been developed specifically
for airline use. The frequency used in this oven was 3,000 megahertz.
Within a year, a practical model 13 inches wide, 14 inches
deep, and 15 inches high appeared, and several new models were
operating in and around Boston. In June, 1947, Electronics magazine
reported the installation of a Radarange in a restaurant, signaling
the commercial use of microwave cooking. It was reported that this

method more than tripled the speed of service. The Radarange became
an important addition to a number of restaurants, and in 1948,
Bernard Proctor and Samuel Goldblith used it for the first time to
conduct research into microwave cooking.
In the United States, the radio frequencies that can be used for
heating are allocated by the Federal Communications Commission
(FCC). The two most popular frequencies for microwave cooking
are 915 and 2,450 megahertz, and the 2,450 frequency is used in
home microwave ovens. It is interesting that patents filed by Spencer
in 1947 mention a frequency on the order of 2,450 megahertz. This
fact is another example of Spencer’s vision in the development of
microwave cooking principles. The Raytheon Company concentrated
on using 2,450 megahertz, and in 1955, the first domestic microwave
oven was introduced. It was not until the late 1960’s, however,
that the price of the microwave oven decreased sufficiently for
the device to become popular. The first patent describing a microwave
heating system being used in conjunction with a conveyor
was issued to Spencer in 1952. Later, based on this development,
continuous industrial applications of microwaves were developed.
Impact
Microwave cooking / 505
Initially, microwaves were viewed as simply an efficient means
of rapidly converting electric energy to heat. Since that time, however,
they have become an integral part of many applications. Because
of the pioneering efforts of Percy L. Spencer, microwave applications
in the food industry for cooking and for other processing
operations have flourished. In the early 1970’s, there were eleven
microwave oven companies worldwide, two of which specialized
in food processing operations, but the growth of the microwave
oven industry has paralleled the growth in the radio and television
industries. In 1984, microwave ovens accounted for more shipments
than had ever been achieved by any appliance—9.1 million units.
By 1989, more than 75 percent of the homes in the United States
had microwave ovens, and in the 1990’s, microwavable foods were
among the fastest-growing products in the food industry. Microwave
energy facilitates reductions in operating costs and required
energy, higher-quality and more reliable products, and positive en-

506 / Microwave cooking
vironmental effects. To some degree, the use of industrial microwave
energy remains in its infancy. New and improved applications
of microwaves will continue to appear.
See also Electric refrigerator; Fluorescent lighting; Food freezing;
Robot (household); Television; Tupperware; Vacuum cleaner;
Washing machine.
Further Reading
Baird, Davis, R. I. G. Hughes, and Alfred Nordmann. Heinrich Hertz:
Classical Physicist, Modern Philosopher. Boston: Kluwer Academic,
1998.
Roman, Mark. “That Marvelous Machine in Your Kitchen.” Reader’s
Digest (February, 1990).
Scott, Otto. The Creative Ordeal: The Story of Raytheon. New York:
Atheneum, 1974.
Simpson, Thomas K. Maxwell on the Electromagnetic Field: A Guided
Study. New Brunswick, N.J.: Rutgers University Press, 1997.
Tolstoy, Ivan. James Clerk Maxwell: A Biography. Chicago: University
of Chicago Press, 1982.

Neoprene
Neoprene
The invention: The first commercially practical synthetic rubber,
Neoprene gave a boost to polymer chemistry and the search for
new materials.
The people behind the invention:
Wallace Hume Carothers (1896-1937), an American chemist
Arnold Miller Collins (1899- ), an American chemist
Elmer Keiser Bolton (1886-1968), an American chemist
Julius Arthur Nieuwland (1879-1936), a Belgian American
priest, botanist, and chemist
Synthetic Rubber: A Mirage?
507
The growing dependence of the industrialized nations upon
elastomers (elastic substances) and the shortcomings of natural
rubber motivated the twentieth century quest for rubber substitutes.
By 1914, rubber had become nearly as indispensable as coal
or iron. The rise of the automobile industry, in particular, had created
a strong demand for rubber. Unfortunately, the availability of
rubber was limited by periodic shortages and spiraling prices. Furthermore,
the particular properties of natural rubber, such as its
lack of resistance to oxygen, oils, and extreme temperatures, restrict
its usefulness in certain applications. These limitations stimulated
a search for special-purpose rubber substitutes.
Interest in synthetic rubber dates back to the 1860 discovery by
the English chemist Greville Williams that the main constituent
of rubber is isoprene, a liquid hydrocarbon. Nineteenth century
chemists attempted unsuccessfully to transform isoprene into
rubber. The first large-scale production of a rubber substitute occurred
during World War I. A British blockade forced Germany to
begin to manufacture methyl rubber in 1916, but methyl rubber
turned out to be a poor substitute for natural rubber. When the
war ended in 1918, a practical synthetic rubber was still only a mirage.
Nevertheless, a breakthrough was on the horizon.

508 / Neoprene
Mirage Becomes Reality
In 1930, chemists at E. I. Du Pont de Nemours discovered the
elastomer known as neoprene. Of the more than twenty chemists
who helped to make this discovery possible, four stand out: Elmer
Bolton, Julius Nieuwland, Wallace Carothers, and Arnold Collins.
Bolton directed Du Pont’s drystuffs department in the mid-
1920’s. Largely because of the rapidly increasing price of rubber, he
initiated a project to synthesize an elastomer from acetylene, a gaseous
hydrocarbon. In December, 1925, Bolton attended the American
Chemical Society’s convention in Rochester, New York, and
heard a presentation dealing with acetylene reactions. The presenter
was Julius Nieuwland, the foremost authority on the chemistry
of acetylene.
Nieuwland was a professor of organic chemistry at the University
of Notre Dame. (One of his students was the legendary football
coach Knute Rockne.) The priest-scientist had been investigating
acetylene reactions for more than twenty years. Using a copper
chloride catalyst he had discovered, he isolated a new compound,
divinylacetylene (DVA). He later treated DVA with a vulcanizing
(hardening) agent and succeeded in producing a rubberlike substance,
but the substance proved to be too soft for practical use.
Bolton immediately recognized the importance of Nieuwland’s
discoveries and discussed with him the possibility of using DVA as
a raw material for a synthetic rubber. Seven months later, an alliance
was formed that permitted Du Pont researchers to use Nieuwland’s
copper catalyst. Bolton hoped that the catalyst would be the key to
making an elastomer from acetylene. As it turned out, Nieuwland’s
catalyst was indispensable for manufacturing neoprene.
Over the next several years, Du Pont scientists tried unsuccessfully
to produce rubberlike materials. Using Nieuwland’s catalyst,
they managed to prepare DVA and also to isolate monovinylacetylene
(MVA), a new compound that eventually proved to be the vital
intermediate chemical in the making of neoprene. Reactions of
MVA and DVA, however, produced only hard, brittle materials.
In 1928, Du Pont hired a thirty-one-year-old Harvard instructor,
Wallace Carothers, to direct the organic chemicals group. He began
a systematic exploration of polymers (complex molecules). In early

1930, he accepted an assignment to investigate the chemistry of
DVA. He appointed one of his assistants, Arnold Collins, to conduct
the laboratory experiments. Carothers suggested that Collins
should explore the reaction between MVA and hydrogen chloride.
His suggestion would lead to the discovery of neoprene.
One of Collins’s experiments yielded a new liquid, and on April
17, 1930, he recorded in his laboratory notebook that the liquid had
solidified into a rubbery substance. When he dropped it on a bench,
it bounced. This was the first batch of neoprene. Carothers named
Collins’s liquid “chloroprene.” Chloroprene is analogous structurally
to isoprene, but it polymerizes much more rapidly. Carothers
conducted extensive investigations of the chemistry of chloroprene
and related compounds. His studies were the foundation for Du
Pont’s development of an elastomer that was superior to all previously
known synthetic rubbers.
Du Pont chemists, including Carothers and Collins, formally introduced
neoprene—originally called “DuPrene”—on November 3,
1931, at the meeting of the American Chemical Society in Akron,
Ohio. Nine months later, the new elastomer began to be sold.
Impact
Neoprene / 509
The introduction of neoprene was a milestone in humankind’s development
of new materials. It was the first synthetic rubber worthy
of the name. Neoprene possessed higher tensile strength than rubber
and much better resistance to abrasion, oxygen, heat, oils, and chemicals.
Its main applications included jacketing for electric wires and
cables, work-shoe soles, gasoline hoses, and conveyor and powertransmission
belting. By 1939, when Adolf Hitler’s troops invaded Poland,
nearly every major industry in America was using neoprene.
After the Japanese bombing of Pearl Harbor, in 1941, the elastomer
became even more valuable to the United States. It helped the United
States and its allies survive the critical shortage of natural rubber that
resulted when Japan seized Malayan rubber plantations.
A scientifically and technologically significant side effect of the
introduction of neoprene was the stimulus that the breakthrough
gave to polymer research. Chemists had long debated whether
polymers were mysterious aggregates of smaller units or were gen-

510 / Neoprene
uine molecules. Carothers ended the debate by demonstrating in a
series of now-classic papers that polymers were indeed ordinary—
but very large—molecules. In the 1930’s, he put polymer studies on
a firm footing. The advance of polymer science led, in turn, to the
development of additional elastomers and synthetic fibers, including
nylon, which was invented by Carothers himself in 1935.
See also Buna rubber; Nylon; Orlon; Plastic; Polyester; Polyethylene;
Polystyrene; Silicones; Teflon.
Further Reading
Furukawa, Yasu. Inventing Polymer Science: Staudinger, Carothers, and
the Emergence of Macromolecular Chemistry. Philadelphia: University
of Pennsylvania Press, 1998.
Hermes, Matthew E. Enough for One Lifetime: Wallace Carothers, Inventor
of Rayon. Washington, D.C.: American Chemical Society
and the Chemical Heritage Foundation, 1996.
Taylor, Graham D., and Patricia E. Sudnik. Du Pont and the International
Chemical Industry. Boston, Mass.: Twayne, 1984.

Neutrino detector
Neutrino detector
The invention: A device that provided the first direct evidence that
the Sun runs on thermonuclear power and challenged existing
models of the Sun.
The people behind the invention:
Raymond Davis, Jr. (1914- ), an American chemist
John Norris Bahcall (1934- ), an American astrophysicist
Missing Energy
511
In 1871, Hermann von Helmholtz, the German physicist, anatomist,
and physiologist, suggested that no ordinary chemical reaction
could be responsible for the enormous energy output of the
Sun. By the 1920’s, astrophysicists had realized that the energy radiated
by the Sun must come from nuclear fusion, in which protons or
nuclei combine to form larger nuclei and release energy. These reactions
were assumed to be taking place deep in the interior of the
Sun, in an immense thermonuclear furnace, where the pressures
and temperatures were high enough to allow fusion to proceed.
Conventional astronomical observations could record only the
particles of light emitted by the much cooler outer layers of the Sun
and could not provide evidence for the existence of a thermonuclear
furnace in the interior. Then scientists realized that the neutrino
might be used to prove that this huge furnace existed. Of all the particles
released in the fusion process, only one type—the neutrino—
interacts so infrequently with matter that it can pass through the
Sun and reach the earth. These neutrinos provide a way to verify directly
the hypothesis of thermonuclear energy generated in stars.
The neutrino was “invented” in 1930 by the American physicist
Wolfgang Pauli to account for the apparent missing energy in the
beta decay, or emission of an electron, from radioactive nuclei. He
proposed that an unseen nuclear particle, which he called a neutrino,
was also emitted in beta decay, and that it carried off the
“missing” energy. To balance the energy but not be observed in the
decay process, Pauli’s hypothetical particle had to have no electrical

512 / Neutrino detector
charge, have little or no mass, and interact only very weakly with
ordinary matter. Typical neutrinos would have to be able to pass
through millions of miles of ordinary matter in order to reach the
earth. Scientists’ detectors, and even the whole earth or Sun, were
essentially transparent as far as Pauli’s neutrinos were concerned.
Because the neutrino is so difficult to detect, it took more than
twenty-five years to confirm its existence. In 1956, Clyde Cowan
and Frederick Reines, both physicists at the Los Alamos National
Laboratory, built the world’s largest scintillation counter, a device to
detect the small flash of light given off when the neutrino strikes
(“interacts” with) a certain substance in the apparatus. They placed
this scintillation counter near the Savannah River Nuclear Reactor,
which was producing about 1 trillion neutrinos every second. Although
only one neutrino interaction was observed in their detector
every twenty minutes, Cowan and Reines were able to confirm the
existence of Pauli’s elusive particle.
The task of detecting the solar neutrinos was even more formidable.
If an apparatus similar to the Cowan and Reines detector were
employed to search for the neutrinos from the Sun, only one interaction
could be expected every few thousand years.
Missing Neutrinos
At about the same time that Cowan and Reines performed their
experiment, another type of neutrino detector was under development
by Raymond Davis, Jr., a chemist at the Brookhaven National
Laboratory. Davis employed an idea, originally suggested in 1948
by the nuclear physicist Bruno Pontecorvo, that when a neutrino interacts
with a chlorine-37 nucleus, it produces a nucleus of argon 37.
Any argon so produced could then be extracted from large volumes
of chlorine-rich liquid by passing helium gas through the liquid.
Since argon 37 is radioactive, it is relatively easy to detect.
Davis tested a version of this neutrino detector, containing about
3,785 liters of carbon tetrachloride liquid, near a nuclear reactor at
the Brookhaven National Laboratory from 1954 to 1956. In the scientific
paper describing his results, Davis suggested that this type of
neutrino detector could be made large enough to permit detection
of solar neutrinos.

Neutrino detector / 513
Patients undergoing nuclear magnetic resonance image (MRI) examinations are placed inside
cylindrical chambers in which their bodies are held rigidly in place. (Digital Stock)
Although Davis’s first attempt to detect solar neutrinos from a
limestone mine at Barberton, Ohio, failed, he continued his search
with a much larger detector 1,478 meters underground in the
Homestake Gold Mine in Lead, South Dakota. The cylindrical tank
(6.1 meters in diameter, 16 meters long, and containing 378,540 liters
of perchloroethylene) was surrounded by water to shield the
detector from neutrons emitted by trace quantities of uranium and
thorium in the walls of the mine. The experiment was conducted
underground to shield it from cosmic radiation.
To describe his results, Davis coined a new unit, the “solar
neutrino unit” (SNU), with 1 SNU indicating the production of
one atom of argon 37 every six days. Astrophysicist John Norris
Bahcall, using the best available astronomical models of the nuclear
reactions going on in the sun’s interior, as well as the physical
properties of the neutrinos, had predicted a capture rate of 50
SNUs in 1963. The 1967 results from Davis’s detector, however,
had an upper limit of only 3 SNUs.

514 / Neutrino detector
Consequences
The main significance of the detection of solar neutrinos by Davis
was the direct confirmation that thermonuclear fusion must be occurring
at the center of the Sun. The low number of solar neutrinos
Davis detected, however, has called into question some of the fundamental
beliefs of astrophysics. As Bahcall explained: “We know
more about the Sun than about any other star....TheSunisalso in
what is believed to be the best-understood stage of stellar evolution....Ifwearetohave
confidence in the many astronomical and
cosmological applications of the theory of stellar evolution, it ought
at least to give the right answers about the Sun.”
Many solutions to the problem of the “missing” solar neutrinos
have been proposed. Most of these solutions can be divided into
two broad classes: those that challenge the model of the sun’s interior
and those that challenge the understanding of the behavior of
the neutrino. Since the number of neutrinos produced is very sensitive
to the temperature of the sun’s interior, some astrophysicists
have suggested that the true solar temperature may be lower than
expected. Others suggest that the sun’s outer layer may absorb
more neutrinos than expected. Some physicists, however, believe
neutrinos may occur in several different forms, only one of which
can be detected by the chlorine detectors.
Alpha Rays (charged helium nuclei)
Beta Rays (charged electrons)
Gamma Rays, X Rays (photons)
Neutrinos
(chargeless, nearly massless subatomic particles)
Skin
Metal Metal
(0.12 cm aluminum) (lead)
Neutrinos can pass through most forms of matter without interacting with other nuclear
particles.

Davis’s discovery of the low number of neutrinos reaching Earth
has focused years of attention on a better understanding of how the
Sun generates its energy and how the neutrino behaves. New and
more elaborate solar neutrino detectors have been built with the
aim of understanding stars, including the Sun, as well as the physics
and behavior of the elusive neutrino.
See also Radio interferometer; Weather satellite.
Further Reading
Neutrino detector / 515
Bartusiak, Marcia. “Underground Astronomer.” Astronomy 28, no. 1
(January, 2000).
“Neutrino Test to Probe Sun.” New Scientist 140, no. 1898 (November
6, 1993).
“Pioneering Neutrino Astronomers to Share 2000 Wolf Prize in
Physics.” Physics Today 53, no. 3 (March, 2000).
Schwarzschild, Bertram. “Can Helium Mixing Explain the Solar
Neutrino Shortages?” Physics Today 50, no. 3 (March, 1997).
Zimmerman, Robert. “The Shadow Boxer.” The Sciences 36, no. 1
(January/February, 1996).

516
Nuclear magnetic resonance
Nuclear magnetic resonance
The invention: Procedure that uses hydrogen atoms in the human
body, strong electromagnets, radio waves, and detection equipment
to produce images of sections of the brain.
The people behind the invention:
Raymond Damadian (1936- ), an American physicist and
inventor
Paul C. Lauterbur (1929- ), an American chemist
Peter Mansfield (1933- ), a scientist at the University of
Nottingham, England
Peering into the Brain
Doctors have always wanted the ability to look into the skull and
see the human brain without harming the patient who is being examined.
Over the years, various attempts were made to achieve this
ability. At one time, the use of X rays, which were first used by Wilhelm
Conrad Röntgen in 1895, seemed to be an option, but it was
found that X rays are absorbed by bone, so the skull made it impossible
to use X-ray technology to view the brain. The relatively recent
use of computed tomography (CT) scanning, a computer-assisted
imaging technology, made it possible to view sections of the head
and other areas of the body, but the technique requires that the part
of the body being “imaged,” or viewed, be subjected to a small
amount of radiation, thereby putting the patient at risk. Positron
emission tomography (PET) could also be used, but it requires that
small amounts of radiation be injected into the patient, which also
puts the patient at risk. Since the early 1940’s, however, a new technology
had been developing.
This technology, which appears to pose no risk to patients, is
called “nuclear magnetic resonance spectroscopy.” It was first used
to study the molecular structures of pure samples of chemicals. This
method developed until it could be used to follow one chemical as it
changed into another, and then another, in a living cell. By 1971,
Raymond Damadian had proposed that body images that were

more vivid and more useful than X rays could be produced by
means of nuclear magnetic resonance spectroscopy. In 1978, he
founded his own company, FONAR, which manufactured the scanners
that are necessary for the technique.
Magnetic Resonance Images
Nuclear magnetic resonance / 517
The first nuclear magnetic resonance images (MRIs) were published
by Paul Lauterbur in 1973. Although there seemed to be no
possibility that MRI could be harmful to patients, everyone involved
in MRI research was very cautious. In 1976, Peter Mansfield,
at the University of Nottingham, England, obtained an MRI of his
partner’s finger. The next year, Paul Bottomley, a member of Waldo
Hinshaw’s research group at the same university, put his left wrist
into an experimental machine that the group had developed. A
vivid cross section that showed layers of skin, muscle, bone, muscle,
and skin, in that order, appeared on the machine’s monitor. Studies
with animals showed no apparent memory or other brain problems.
In 1978, Electrical and Musical Industries (EMI), a British corporate
pioneer in electronics that merged with Thorn in 1980, obtained the
first MRI of the human head. It took six minutes.
An MRI of the brain, or any other part of the body, is made possible
by the water content of the body. The gray matter of the brain
contains more water than the white matter does. The blood vessels
and the blood itself also have water contents that are different from
those of other parts of the brain. Therefore, the different structures
and areas of the brain can be seen clearly in an MRI. Bone contains
very little water, so it does not appear on the monitor. This is why
the skull and the backbone cause no interference when the brain or
the spinal cord is viewed.
Every water molecule contains two hydrogen atoms and one
oxygen atom. A strong electromagnetic field causes the hydrogen
molecules to line up like marchers in a parade. Radio waves can be
used to change the position of these parallel hydrogen molecules.
When the radio waves are discontinued, a small radio signal is
produced as the molecules return to their marching position. This
distinct radio signal is the basis for the production of the image on
a computer screen.

518 / Nuclear magnetic resonance
Hydrogen was selected for use in MRI work because it is very
abundant in the human body, it is part of the water molecule, and it
has the proper magnetic qualities. The nucleus of the hydrogen
atom consists of a single proton, a particle with a positive charge.
The signal from the hydrogen’s proton is comparatively strong.
There are several methods by which the radio signal from the
hydrogen atom can be converted into an image. Each method
uses a computer to create first a two-dimensional, then a threedimensional,
image.
Peter Mansfield’s team at the University of Nottingham holds
the patent for the slice-selection technique that makes it possible to
excite and image selectively a specific cross section of the brain or
any other part of the body. This is the key patent in MRI technology.
Damadian was granted a patent that described the use of two coils,
one to drive and one to pick up signals across selected portions of
the human body. EMI, the company that introduced the X-ray scanner
for CT images, developed a commercial prototype for the MRI.
The British Technology Group, a state-owned company that helps to
bring innovations to the marketplace, has sixteen separate MRIrelated
patents. Ten years after EMI produced the first image of the
human brain, patents and royalties were still being sorted out.
Consequences
MRI technology has revolutionized medical diagnosis, especially
in regard to the brain and the spinal cord. For example, in multiple
sclerosis, the loss of the covering on nerve cells can be detected. Tumors
can be identified accurately. The painless and noninvasive use
of MRI has almost completely replaced the myelogram, which involves
using a needle to inject dye into the spine.
Although there is every indication that the use of MRI is very
safe, there are some people who cannot benefit from this valuable
tool. Those whose bodies contain metal cannot be placed into the
MRI machine. No one instrument can meet everyone’s needs.
The development of MRI stands as an example of the interaction
of achievements in various fields of science. Fundamental physics,
biochemistry, physiology, electronic image reconstruction, advances
in superconducting wires, the development of computers, and ad-

vancements in anatomy all contributed to the development of MRI.
Its development is also the result of international efforts. Scientists
and laboratories in England and the United States pioneered the
technology, but contributions were also made by scientists in France,
Switzerland, and Scotland. This kind of interaction and cooperation
can only lead to greater understanding of the human brain.
See also Amniocentesis; CAT scanner; Electrocardiogram; Electroencephalogram;
Mammography; Ultrasound; X-ray image intensifier.
Further Reading
Nuclear magnetic resonance / 519
Elster, Allen D., and Jonathan H. Burdette. Questions and Answers in
Magnetic Resonance Imaging. 2d ed. St. Louis, Mo.: Mosby, 2001.
Mackay, R. Stuart. Medical Images and Displays: Comparisons of Nuclear
Magnetic Resonance, Ultrasound, X-rays, and Other Modalities.
New York: Wiley, 1984.
Mattson, James, and Merrill Simon. The Story of MRI: The Pioneers of
NMR and Magnetic Resonance in Medicine. Jericho, N.Y.: Dean
Books, 1996.
Wakefield, Julie. “The ‘Indomitable’ MRI.” Smithsonian 31, no. 3
(June, 2000).
Wolbarst, Anthony B. Looking Within: How X-ray, CT, MRI, Ultrasound,
and Other Medical Images Are Created, and How they Help
Physicians Save Lives. Berkeley: University of California Press,
1999.

520
Nuclear power plant
Nuclear power plant
The invention: The first full-scale commercial nuclear power plant,
which gave birth to the nuclear power industry.
The people behind the invention:
Enrico Fermi (1901-1954), an Italian American physicist who
won the 1938 Nobel Prize in Physics
Otto Hahn (1879-1968), a German physical chemist who won the
1944 Nobel Prize in Chemistry
Lise Meitner (1878-1968), an Austrian Swedish physicist
Hyman G. Rickover (1898-1986), a Polish American naval officer
Discovering Fission
Nuclear fission involves the splitting of an atomic nucleus, leading
to the release of large amounts of energy. Nuclear fission was
discovered in Germany in 1938 by Otto Hahn after he had bombarded
uranium with neutrons and observed traces of radioactive
barium. When Hahn’s former associate, Lise Meitner, heard of this,
she realized that the neutrons may have split the uranium nuclei
(each of which holds 92 protons) into two smaller nuclei to produce
barium (56 protons) and krypton (36 protons). Meitner and her
nephew, Otto Robert Frisch, were able to calculate the enormous energy
that would be released in this type of reaction. They published
their results early in 1939.
Nuclear fission was quickly verified in several laboratories, and
the Danish physicist Niels Bohr soon demonstrated that the rare uranium
235 (U-235) isotope is much more likely to fission than the common
uranium 238 (U-238) isotope, which makes up 99.3 percent of
natural uranium. It was also recognized that fission would produce
additional neutrons that could cause new fissions, producing even
more neutrons and thus creating a self-sustaining chain reaction. In
this process, the fissioning of one gram of U-235 would release about
as much energy as the burning of three million tons of coal.
The first controlled chain reaction was demonstrated on December
2, 1942, in a nuclear reactor at the University of Chicago, under

the leadership of Enrico Fermi. He used a graphite moderator to
slow the neutrons by collisions with carbon atoms. “Critical mass”
was achieved when the mass of graphite and uranium assembled
was large enough that the number of neutrons not escaping from
the pile would be sufficient to sustain a U-235 chain reaction. Cadmium
control rods could be inserted to absorb neutrons and slow
the reaction.
It was also recognized that the U-238 in the reactor would absorb
accelerated neutrons to produce the new element plutonium, which
is also fissionable. During World War II (1939-1945), large reactors
were built to “breed” plutonium, which was easier to separate than
U-235. An experimental breeder reactor at Arco, Idaho, was the first
to use the energy of nuclear fission to produce a small amount of
electricity (about 100 watts) on December 20, 1951.
Nuclear Electricity
Nuclear power plant / 521
Power reactors designed to produce substantial amounts of
electricity use the heat generated by fission to produce steam or
hot gas to drive a turbine connected to an ordinary electric generator.
The first power reactor design to be developed in the United
States was the pressurized water reactor (PWR). In the PWR, water
under high pressure is used both as the moderator and as the coolant.
After circulating through the reactor core, the hot pressurized
water flows through a heat exchanger to produce steam. Reactors
moderated by “heavy water” (in which the hydrogen in the water
is replaced with deuterium, which contains an extra neutron) can
operate with natural uranium.
The pressurized water system was used in the first reactor to
produce substantial amounts of power, the experimental Mark I
reactor. It was started up on May 31, 1953, at the Idaho National
Engineering Laboratory. The Mark I became the prototype for the
reactor used in the first nuclear-powered submarine. Under the
leadership of Hyman G. Rickover, who was head of the Division of
Naval Reactors of the Atomic Energy Commission (AEC), Westinghouse
Electric Corporation was engaged to build a PWR system
to power the submarine USS Nautilus. It began sea trials in January
of 1955 and ran for two years before refueling.

522 / Nuclear power plant
Cooling towers of a nuclear power plant. (PhotoDisc)
In the meantime, the first experimental nuclear power plant for
generating electricity was completed in the Soviet Union in June of
1954, under the direction of the Soviet physicist Igor Kurchatov. It
produced 5 megawatts of electric power. The first full-scale nuclear
power plant was built in England under the direction of the British
nuclear engineer Sir Christopher Hinton. It began producing about
90 megawatts of electric power in October, 1956.

On December 2, 1957, on the fifteenth anniversary of the first controlled
nuclear chain reaction, the Shippingport Atomic Power Station
in Shippingport, Pennsylvania, became the first full-scale commercial
nuclear power plant in the United States. It produced about
60 megawatts of electric power for the Duquesne Light Company until
1964, when its reactor core was replaced, increasing its power to
100 megawatts with a maximum capacity of 150 megawatts.
Consequences
Nuclear power plant / 523
The opening of the Shippingport Atomic Power Station marked
the beginning of the nuclear power industry in the United States,
with all of its glowing promise and eventual problems. It was predicted
that electrical energy would become too cheap to meter. The
AEC hoped to encourage the participation of industry, with government
support limited to research and development. They encouraged
a variety of reactor types in the hope of extending technical
knowledge.
The Dresden Nuclear Power Station, completed by Commonwealth
Edison in September, 1959, at Morris, Illinois, near Chicago,
was the first full-scale privately financed nuclear power station in
the United States. By 1973, forty-two plants were in operation producing
26,000 megawatts, fifty more were under construction, and
about one hundred were on order. Industry officials predicted that
50 percent of the nation’s electric power would be nuclear by the
end of the twentieth century.
The promise of nuclear energy has not been completely fulfilled.
Growing concerns about safety and waste disposal have led to increased
efforts to delay or block the construction of new plants. The
cost of nuclear plants rose as legal delays and inflation pushed costs
higher, so that many in the planning stages could no longer be competitive.
The 1979 Three Mile Island accident in Pennsylvania and
the much more serious 1986 Chernobyl accident in the Soviet Union
increased concerns about the safety of nuclear power. Nevertheless,
by 1986, more than one hundred nuclear power plants were operating
in the United States, producing about 60,000 megawatts of
power. More than three hundred reactors in twenty-five countries
provide about 200,000 megawatts of electric power worldwide.

524 / Nuclear power plant
Many believe that, properly controlled, nuclear energy offers a
clean-energy solution to the problem of environmental pollution.
See also Breeder reactor; Compressed-air-accumulating power
plant; Fuel cell; Geothermal power; Nuclear reactor; Solar thermal
engine; Tidal power plant.
Further Reading
Henderson, Harry. Nuclear Power: A Reference Handbook. Santa
Barbara, Calif.: ABC-CLIO, 2000.
Rockwell, Theodore. The Rickover Effect: The Inside Story of How Admiral
Hyman Rickover Built the Nuclear Navy. New York: J. Wiley,
1995.
Shea, William R. Otto Hahn and the Rise of Nuclear Physics. Boston: D.
Reidel, 1983.
Sime, Ruth Lewin. Lise Meitner: A Life in Physics. Berkeley: University
of California Press, 1996.

Nuclear reactor
Nuclear reactor
The invention: The first nuclear reactor to produce substantial
quantities of plutonium, making it practical to produce usable
amounts of energy from a chain reaction.
The people behind the invention:
Enrico Fermi (1901-1954), an American physicist
Martin D. Whitaker (1902-1960), the first director of Oak Ridge
National Laboratory
Eugene Paul Wigner (1902-1995), the director of research and
development at Oak Ridge
The Technology to End a War
525
The construction of the nuclear reactor at Oak Ridge National
Laboratory in 1943 was a vital part of the Manhattan Project, the effort
by the United States during World War II (1939-1945) to develop
an atomic bomb. The successful operation of that reactor
was a major achievement not only for the project itself but also for
the general development and application of nuclear technology.
The first director of the Oak Ridge National Laboratory was Martin
D. Whitaker; the director of research and development was Eugene
Paul Wigner.
The nucleus of an atom is made up of protons and neutrons. “Fission”
is the process by which the nucleus of certain elements is split
in two by a neutron from some material that emits an occasional
neutron naturally. When an atom splits, two things happen: A tremendous
amount of thermal energy is released, and two or three
neutrons, on the average, escape from the nucleus. If all the atoms in
a kilogram of “uranium 235” were to fission, they would produce as
much heat energy as the burning of 3 million kilograms of coal. The
neutrons that are released are important, because if at least one of
them hits another atom and causes it to fission (and thus to release
more energy and more neutrons), the process will continue. It will
become a self-sustaining chain reaction that will produce a continuing
supply of heat.

526 / Nuclear reactor
Inside a reactor, a nuclear chain reaction is controlled so that it
proceeds relatively slowly. The most familiar use for the heat thus
released is to boil water and make steam to turn the turbine generators
that produce electricity to serve industrial, commercial, and
residential needs. The fissioning process in a weapon, however, proceeds
very rapidly, so that all the energy in the atoms is produced
and released virtually at once. The first application of nuclear technology,
which used a rapid chain reaction, was to produce the two
atomic bombs that ended World War II.
Breeding Bomb Fuel
The work that began at Oak Ridge in 1943 was made possible by a
major event that took place in 1942. At the University of Chicago,
Enrico Fermi had demonstrated for the first time that it was possible to
achieve a self-sustaining atomic chain reaction. More important, the reaction
could be controlled: It could be started up, it could generate heat
and sufficient neutrons to keep itself going, and it could be turned off.
That first chain reaction was very slow, and it generated very little heat;
but it demonstrated that controlled fission was possible.
Any heat-producing nuclear reaction is an energy conversion
process that requires fuel. There is only one readily fissionable element
that occurs naturally and can be used as fuel. It is a form of
uranium called uranium 235. It makes up less than 1 percent of all
naturally occurring uranium. The remainder is uranium 238, which
does not fission readily. Even uranium 235, however, must be enriched
before it can be used as fuel.
The process of enrichment increases the concentration of uranium
235 sufficiently for a chain reaction to occur. Enriched uranium is used
to fuel the reactors used by electric utilities. Also, the much more plentiful
uranium 238 can be converted into plutonium 239, a form of the
human-made element plutonium, which does fission readily. That
conversion process is the way fuel is produced for a nuclear weapon.
Therefore, the major objective of the Oak Ridge effort was to develop a
pilot operation for separating plutonium from the uranium in which it
was produced. Large-scale plutonium production, which had never
been attempted before, eventually would be done at the Hanford Engineer
Works in Washington. First, however, plutonium had to be pro-

duced successfully on a small scale at Oak Ridge.
The reactor was started up on November 4, 1943. By March 1,
1944, the Oak Ridge laboratory had produced several grams of plutonium.
The material was sent to the Los Alamos laboratory in New
Mexico for testing. By July, 1944, the reactor operated at four times
its original power level. By the end of that year, however, plutonium
production at Oak Ridge had ceased, and the reactor thereafter was
used principally to produce radioisotopes for physical and biological
research and for medical treatment. Ultimately, the Hanford Engineer
Works’ reactors produced the plutonium for the bomb that
was dropped on Nagasaki, Japan, on August 9, 1945.
The original objectives for which Oak Ridge had been built had
been achieved, and subsequent activity at the facility was directed
toward peacetime missions that included basic studies of the structure
of matter.
Impact
Nuclear reactor / 527
Part of the Oak Ridge National Laboratory, where plutonium was separated to create the
first atomic bomb. (Martin Marietta)
The most immediate impact of the work done at Oak Ridge was
its contribution to ending World War II. When the atomic bombs
were dropped, the war ended, and the United States emerged intact.
The immediate and long-range devastation to the people of Japan,

528 / Nuclear reactor
however, opened the public’s eyes to the almost unimaginable
death and destruction that could be caused by a nuclear war. Fears
of such a war remain to this day, especially as more and more nations
develop the technology to build nuclear weapons.
On the other hand, great contributions to human civilization
have resulted from the development of nuclear energy. Electric
power generation, nuclear medicine, spacecraft power, and ship
propulsion have all profited from the pioneering efforts at the Oak
Ridge National Laboratory. Currently, the primary use of nuclear
energy is to produce electric power. Handled properly, nuclear energy
may help to solve the pollution problems caused by the burning
of fossil fuels.
See also Breeder reactor; Compressed-air-accumulating power
plant; Fuel cell; Geothermal power; Heat pump; Nuclear power
plant; Solar thermal engine; Tidal power plant.
Further Reading
Epstein, Sam, Beryl Epstein, and Raymond Burns. Enrico Fermi: Father
of Atomic Power. Champaign, Ill.: Garrard, 1970.
Johnson, Leland, and Daniel Schaffer. Oak Ridge National Laboratory:
The First Fifty Years. Knoxville: University of Tennessee Press,
1994.
Morgan, K. Z., and Ken M. Peterson. The Angry Genie: One Man’s
Walk Through the Nuclear Age. Norman: University of Oklahoma
Press, 1999.
Wagner, Francis S. Eugene P. Wigner, An Architect of the Atomic Age.
Toronto: Rákóczi Foundation, 1981.

Nylon
Nylon
The invention: A resilient, high-strength polymer with applications
ranging from women’s hose to safety nets used in space
flights.
The people behind the invention:
Wallace Hume Carothers (1896-1937), an American organic
chemist
Charles M. A. Stine (1882-1954), an American chemist and
director of chemical research at Du Pont
Elmer Keiser Bolton (1886-1968), an American industrial
chemist
Pure Research
529
In the twentieth century, American corporations created industrial
research laboratories. Their directors became the organizers of
inventions, and their scientists served as the sources of creativity.
The research program of E. I. Du Pont de Nemours and Company
(Du Pont), through its most famous invention—nylon—became the
model for scientifically based industrial research in the chemical
industry.
During World War I (1914-1918), Du Pont tried to diversify,
concerned that after the war it would not be able to expand with
only explosives as a product. Charles M. A. Stine, Du Pont’s director
of chemical research, proposed that Du Pont should move
into fundamental research by hiring first-rate academic scientists
and giving them freedom to work on important problems in
organic chemistry. He convinced company executives that a program
to explore the fundamental science underlying Du Pont’s
technology would ultimately result in discoveries of value to the
company. In 1927, Du Pont gave him a new laboratory for research.
Stine visited universities in search of brilliant, but not-yetestablished,
young scientists. He hired Wallace Hume Carothers.
Stine suggested that Carothers do fundamental research in polymer
chemistry.

530 / Nylon
Before the 1920’s, polymers were a mystery to chemists. Polymeric
materials were the result of ingenious laboratory practice,
and this practice ran far ahead of theory and understanding. German
chemists debated whether polymers were aggregates of smaller
units held together by some unknown special force or genuine molecules
held together by ordinary chemical bonds.
German chemist Hermann Staudinger asserted that they were
large molecules with endlessly repeating units. Carothers shared
this view, and he devised a scheme to prove it by synthesizing very
large molecules by simple reactions in such a way as to leave no
doubt about their structure. Carothers’s synthesis of polymers revealed
that they were ordinary molecules but giant in size.
The Longest Molecule
In April, 1930, Carothers’s research group produced two major
innovations: neoprene synthetic rubber and the first laboratorysynthesized
fiber. Neither result was the goal of their research. Neoprene
was an incidental discovery during a project to study short
polymers of acetylene. During experimentation, an unexpected substance
appeared that polymerized spontaneously. Carothers studied
its chemistry and developed the process into the first successful synthetic
rubber made in the United States.
The other discovery was an unexpected outcome of the group’s
project to synthesize polyesters by the reaction of acids and alcohols.
Their goal was to create a polyester that could react indefinitely
to form a substance with high molecular weight. The scientists
encountered a molecular weight limit of about 5,000 units to the
size of the polyesters, until Carothers realized that the reaction also
produced water, which was decomposing polyesters back into acid
and alcohol. Carothers and his associate Julian Hill devised an apparatus
to remove the water as it formed. The result was a polyester
with a molecular weight of more than 12,000, far higher than any
previous polymer.
Hill, while removing a sample from the apparatus, found that he
could draw it out into filaments that on cooling could be stretched to
form very strong fibers. This procedure, called “cold-drawing,” oriented
the molecules from a random arrangement into a long, linear

one of great strength. The polyester fiber, however, was unsuitable
for textiles because of its low melting point.
In June, 1930, Du Pont promoted Stine; his replacement as research
director was Elmer Keiser Bolton. Bolton wanted to control
fundamental research more closely, relating it to projects that would
pay off and not allowing the research group freedom to pursue
purely theoretical questions.
Despite their differences, Carothers and Bolton shared an interest
in fiber research. On May 24, 1934, Bolton’s assistant Donald
Coffman “drew” a strong fiber from a new polyamide. This was the
first nylon fiber, although not the one commercialized by Du Pont.
The nylon fiber was high-melting and tough, and it seemed that a
practical synthetic fiber might be feasible.
By summer of 1934, the fiber project was the heart of the research
group’s activity. The one that had the best fiber properties was nylon
5-10, the number referring to the number of carbon atoms in the
amine and acid chains. Yet the nylon 6-6 prepared on February 28,
1935, became Du Pont’s nylon. Nylon 5-10 had some advantages,
but Bolton realized that its components would be unsuitable for
commercial production, whereas those of nylon 6-6 could be obtained
from chemicals in coal.
A determined Bolton pursued nylon’s practical development,
a process that required nearly four years. Finally, in April, 1937,
Du Pont filed a patent for synthetic fibers, which included a statement
by Carothers that there was no previous work on polyamides;
this was a major breakthrough. After Carothers’s death
on April 29, 1937, the patent was issued posthumously and assigned
to Du Pont. Du Pont made the first public announcement
of nylon on October 27, 1938.
Impact
Nylon / 531
Nylon was a generic term for polyamides, and several types of
nylon became commercially important in addition to nylon 6-6.
These nylons found widespread use as both a fiber and a moldable
plastic. Since it resisted abrasion and crushing, was nonabsorbent,
was stronger than steel on a weight-for-weight basis, and was almost
nonflammable, it embraced an astonishing range of uses: in

532 / Nylon
laces, screens, surgical sutures, paint, toothbrushes, violin strings,
coatings for electrical wires, lingerie, evening gowns, leotards, athletic
equipment, outdoor furniture, shower curtains, handbags, sails,
luggage, fish nets, carpets, slip covers, bus seats, and even safety
nets on the space shuttle.
The invention of nylon stimulated notable advances in the chemistry
and technology of polymers. Some historians of technology
have even dubbed the postwar period as the “age of plastics,” the
age of synthetic products based on the chemistry of giant molecules
made by ingenious chemists and engineers.
The success of nylon and other synthetics, however, has come at
a cost. Several environmental problems have surfaced, such as those
created by the nondegradable feature of some plastics, and there is
the problem of the increasing utilization of valuable, vanishing resources,
such as petroleum, which contains the essential chemicals
needed to make polymers. The challenge to reuse and recycle these
polymers is being addressed by both scientists and policymakers.
See also Buna rubber; Neoprene; Orlon; Plastic; Polyester; Polyethylene;
Polystyrene.
Further Reading
Furukawa, Yasu. Inventing Polymer Science: Staudinger, Carothers, and
the Emergence of Macromolecular Chemistry. Philadelphia: University
of Pennsylvania Press, 1998.
Handley, Susannah. Nylon: The Story of a Fashion Revolution: A Celebration
of Design from Art Silk to Nylon and Thinking Fibres. Baltimore:
Johns Hopkins University Press, 1999.
Hermes, Matthew E. Enough for One Lifetime: Wallace Carothers, Inventor
of Rayon. Washington, D.C.: American Chemical Society
and the Chemical Heritage Foundation, 1996.
Joyce, Robert M. Elmer Keiser Bolton: June 23, 1886-July 30, 1968.
Washington, D.C.: National Academy Press, 1983.

Oil-well drill bit
Oil-well drill bit
The invention: A rotary cone drill bit that enabled oil-well drillers
to penetrate hard rock formations.
The people behind the invention:
Howard R. Hughes (1869-1924), an American lawyer, drilling
engineer, and inventor
Walter B. Sharp (1860-1912), an American drilling engineer,
inventor, and partner to Hughes
Digging for Oil
533
A rotary drill rig of the 1990’s is basically unchanged in its essential
components from its earlier versions of the 1900’s. A drill bit is
attached to a line of hollow drill pipe. The latter passes through a
hole on a rotary table, which acts essentially as a horizontal gear
wheel and is driven by an engine. As the rotary table turns, so do the
pipe and drill bit.
During drilling operations, mud-laden water is pumped under
high pressure down the sides of the drill pipe and jets out with great
force through the small holes in the rotary drill bit against the bottom
of the borehole. This fluid then returns outside the drill pipe to
the surface, carrying with it rock material cuttings from below. Circulated
rock cuttings and fluids are regularly examined at the surface
to determine the precise type and age of rock formation and for
signs of oil and gas.
A key part of the total rotary drilling system is the drill bit, which
has sharp cutting edges that make direct contact with the geologic
formations to be drilled. The first bits used in rotary drilling were
paddlelike “fishtail” bits, fairly successful for softer formations, and
tubular coring bits for harder surfaces. In 1893, M. C. Baker and C. E.
Baker brought a rotary water-well drill rig to Corsicana, Texas, for
modification to deeper oil drilling. This rig led to the discovery of
the large Corsicana-Powell oil field in Navarro County, Texas. This
success also motivated its operators, the American Well and Prospecting
Company, to begin the first large-scale manufacture of rotary
drilling rigs for commercial sale.

534 / Oil-well drill bit
In the earliest rotary drilling for oil, short fishtail bits were the
tool of choice, insofar as they were at that time the best at being able
to bore through a wide range of geologic strata without needing frequent
replacement. Even so, in the course of any given oil well,
many bits were required typically in coastal drilling in the Gulf of
Mexico. Especially when encountering locally harder rock units
such as limestone, dolomite, or gravel beds, fishtail bits would typically
either curl backward or break off in the hole, requiring the
time-consuming work of pulling out all drill pipe and “fishing” to
retrieve fragments and clear the hole.
Because of the frequent bit wear and damage, numerous small
blacksmith shops established themselves near drill rigs, dressing or
sharpening bits with a hand forge and hammer. Each bit-forging
shop had its own particular way of shaping bits, producing a wide
variety of designs. Nonstandard bit designs were frequently modified
further as experiments to meet the specific requests of local drillers
encountering specific drilling difficulties in given rock layers.
Speeding the Process
In 1907 and 1908, patents were obtained in New Jersey and
Texas for steel, cone-shaped drill bits incorporating a roller-type
coring device with many serrated teeth. Later in 1908, both patents
were bought by lawyer Howard R. Hughes.
Although comparatively weak rocks such as sands, clays, and
soft shales could be drilled rapidly (at rates exceeding 30 meters per
hour), in harder shales, lime-dolostones, and gravels, drill rates of 1
meter per hour or less were not uncommon. Conventional drill bits
of the time had average operating lives of three to twelve hours.
Economic drilling mandated increases in both bit life and drilling
rate. Directly motivated by his petroleum prospecting interests,
Hughes and his partner, Walter B. Sharp, undertook what were
probably the first recorded systematic studies of drill bit performance
while matched against specific rock layers.
Although many improvements in detail and materials have been
made to the Hughes cone bit since its inception in 1908, its basic design
is still used in rotary drilling. One of Hughes’s major innovations
was the much larger size of the cutters, symmetrically distrib-

Howard R. Hughes
Oil-well drill bit / 535
Howard Hughes (1905-1976) is famous for having been one
of the most dashing, innovative, quirky tycoons of the twentieth
century. It all started with his father, Howard R. Hughes. In
fact it was the father’s enterprise, Hughes Tool Company, that
the son took over at age eighteen and built into an immense financial
empire based on high-tech products.
The senior Hughes was born in Lancaster, Missouri, in 1869.
He spent his boyhood in Keokuk, Iowa, where his own father
practiced law. He himself studied law at Harvard University
and the University of Iowa and then joined his father’s practice,
but not for long. In 1901 news came of a big oil strike near Beaumont,
Texas. Like hundreds of other ambitious men, Hughes
headed there. By 1906 he had immersed himself in the technical
problems of drilling and began experimenting to improve drill
bits. He produced a wooden model of the roller-type drill two
years later while in Oil City, Louisiana. With business associate
Walter Sharp he successfully tested a prototype in an oil well in
the Goose Creek field near Houston. It drilled faster and more
efficiently than those then in use.
Hughes and Sharp opened the Sharp-Hughes Tool Company
to manufacture the drills and related equipment, and their
products quickly became the industry standard. A shrewd business
strategist, Hughes leased, rather than sold, his drill bits
for $30,000 per well, retaining his patents to preserve his monopoly
over the rotary drill technology. After Sharp died in
1912, Hughes changed the company to the Hughes Tool Company.
When Hughes himself died in 1924, he left his son, then a
student at Rice Institute (later Rice University), the company
and a million-dollar fortune, which Hughes junior would eventually
multiply hundreds of times over.
uted as a large number of small individual teeth on the outer face of
two or more cantilevered bearing pins. In addition, “hard facing”
was employed to drill bit teeth to increase usable life. Hard facing is
a metallurgical process basically consisting of wedding a thin layer
of a hard metal or alloy of special composition to a metal surface to
increase its resistance to abrasion and heat. A less noticeable but
equally essential innovation, not included in other drill bit patents,

536 / Oil-well drill bit
was an ingeniously designed gauge surface that provided strong
uniform support for all the drill teeth. The force-fed oil lubrication
was another new feature included in Hughes’s patent and prototypes,
reducing the power necessary to rotate the bit by 50 percent
over that of prior mud or water lubricant designs.
Impact
In 1925, the first superhard facing was used on cone drill bits. In
addition, the first so-called self-cleaning rock bits appeared from
Hughes, with significant advances in roller bearings and bit tooth
shape translating into increased drilling efficiency. The much larger
teeth were more adaptable to drilling in a wider variety of geological
formations than earlier models. In 1928, tungsten carbide was
introduced as an additional bit facing hardener by Hughes metallurgists.
This, together with other improvements, resulted in the
Hughes ACME tooth form, which has been in almost continuous
use since 1926.
Many other drilling support technologies, such as drilling mud,
mud circulation pumps, blowout detectors and preventers, and
pipe properties and connectors have enabled rotary drilling rigs to
reach new depths (exceeding 5 kilometers in 1990). The successful
experiments by Hughes in 1908 were critical initiators of these developments.
See also Geothermal power; Steelmaking process; Thermal
cracking process.
Further Reading
Brantly, John Edward. History of Oil Well Drilling. Houston: Gulf
Publishing, 1971.
Charlez, Philippe A. Rock Mechanics. Vol. 2: Petroleum Applications.
Paris: Editions Technip, 1997.
Rao, Karanam Umamaheshwar, and Misra Banabihari. Principles of
Rock Drilling. Brookfield, Vt.: Balkema, 1998.

Optical disk
Optical disk
The invention: A nonmagnetic storage medium for computers that
can hold much greater quantities of data than similar size magnetic
media, such as hard and floppy disks.
The people behind the invention:
Klaas Compaan, a Dutch physicist
Piet Kramer, head of Philips’ optical research laboratory
Lou F. Ottens, director of product development for Philips’
musical equipment division
George T. de Kruiff, manager of Philips’ audio-product
development department
Joop Sinjou, a Philips project leader
Holograms Can Be Copied Inexpensively
537
Holography is a lensless photographic method that uses laser
light to produce three-dimensional images. This is done by splitting
a laser beam into two beams. One of the beams is aimed at the object
whose image is being reproduced so that the laser light will reflect
from the object and strike a photographic plate or film. The second
beam of light is reflected from a mirror near the object and also
strikes the photographic plate or film. The “interference pattern,”
which is simply the pattern created by the differences between the
two reflected beams of light, is recorded on the photographic surface.
The recording that is made in this way is called a “hologram.”
When laser light or white light strikes the hologram, an image is created
that appears to be a three-dimensional object.
Early in 1969, Radio Corporation of America (RCA) engineers
found a way to copy holograms inexpensively by impressing interference
patterns on a nickel sheet that then became a mold from
which copies could be made. Klaas Compaan, a Dutch physicist,
learned of this method and had the idea that images could be recorded
in a similar way and reproduced on a disk the size of a phonograph
record. Once the images were on the disk, they could be
projected onto a screen in any sequence. Compaan saw the possibilities
of such a technology in the fields of training and education.

538 / Optical disk
Computer Data Storage Breakthrough
In 1969, Compaan shared his idea with Piet Kramer, who was the
head of Philips’ optical research laboratory. The idea intrigued
Kramer. Between 1969 and 1971, Compaan spent much of his time
working on the development of a prototype.
By September, 1971, Compaan and Kramer, together with a handful
of others, had assembled a prototype that could read a blackand-white
video signal from a spinning glass disk. Three months
later, they demonstrated it for senior managers at Philips. In July,
1972, a color prototype was demonstrated publicly. After the demonstration,
Philips began to consider putting sound, rather than images,
on the disks. The main attraction of that idea was that the 12inch
(305-millimeter) disks would hold up to forty-eight hours of
music. Very quickly, however, Lou F. Ottens, director of product development
for Philips’ musical equipment division, put an end to
any talk of a long-playing audio disk.
Ottens had developed the cassette-tape cartridge in the 1960’s.
He had plenty of experience with the recording industry, and he had
no illusions that the industry would embrace that new medium. He
was convinced that the recording companies would consider fortyeight
hours of music unmarketable. He also knew that any new
medium would have to offer a dramatic improvement over existing
vinyl records.
In 1974, only three years after the first microprocessor (the basic
element of computers) was invented, designing a digital consumer
product—rather than an analog product such as those that were already
commonly accepted—was risky. (Digital technology uses
numbers to represent information, whereas analog technology represents
information by mechanical or physical means.) When
George T. de Kruiff became Ottens’s manager of audio-product
development in June, 1974, he was amazed that there were no
digital circuit specialists in the audio department. De Kruiff recruited
new digital engineers, bought computer-aided design
tools, and decided that the project should go digital.
Within a few months, Ottens’s engineers had rigged up a digital
system. They used an audio signal that was representative of an
acoustical wave, sampled it to change it to digital form, and en-

Optical disk / 539
coded it as a series of pulses. On the disk itself, they varied the
length of the “dimples” that were used to represent the sound so
that the rising and falling edges of the series of pulses corresponded
to the dimples’ walls. A helium-neon laser was reflected from
the dimples to photodetectors that were connected to a digital-toanalog
converter.
In 1978, Philips demonstrated a prototype for Polygram (a West
German company) and persuaded Polygram to develop an inexpensive
disk material with the appropriate optical qualities. Most
important was that the material could not warp. Polygram spent
about $150,000 and three months to develop the disk. In addition, it
was determined that the gallium-arsenide (GaAs) laser would be
used in the project. Sharp Corporation agreed to manufacture a
long-life GaAs diode laser to Philips’ specifications.
The optical-system designers wanted to reduce the number
of parts in order to decrease manufacturing costs and improve
reliability. Therefore, the lenses were simplified and considerable
work was devoted to developing an error-correction code.
Philips and Sony engineers also worked together to create a standard
format. In 1983, Philips made almost 100,000 units of optical
disks.
Optical Disk
An optical memory.
Laser Beam
Direction of
Rotation
Direction of Laser

540 / Optical disk
Consequences
In 1983, one of the most successful consumer products of all time
was introduced: the optical-disk system. The overwhelming success
of optical-disk reproduction led to the growth of a multibillion-dollar
industry around optical information and laid the groundwork
for a whole crop of technologies that promise to revolutionize computer
data storage. Common optical-disk products are the compact
disc (CD), the compact disc read-only memory (CD-ROM), the
write-once, read-many (WORM) erasable disk, and CD-I (interactive
CD).
The CD-ROM, the WORM, and the erasable optical disk, all of
which are used in computer applications, can hold more than 550
megabytes, from 200 to 800 megabytes, and 650 megabytes of data,
respectively.
The CD-ROM is a nonerasable disc that is used to store computer
data. After the write-once operation is performed, a WORM becomes
a read-only optical disk. An erasable optical disk can be
erased and rewritten easily. CD-ROMs, coupled with expert-system
technology, are expected to make data retrieval easier. The CD-ROM,
the WORM, and the erasable optical disk may replace magnetic
hard and floppy disks as computer data storage devices.
See also Bubble memory; Compact disc; Computer chips;
Floppy disk; Hard disk; Holography.
Further Reading
Fox, Barry. “Head to Head in the Recording Wars.” New Scientist
136, no. 1843 (October 17, 1992).
Goff, Leslie. “Philips’ Eye on the Future.” Computerworld 33, no. 32
(August 9, 1999).
Kolodziej, Stan. “Optical Discs: The Dawn of a New Era in Mass
Storage.” Canadian Datasystems 14, no. 9 (September, 1982). 36-39.
Savage, Maria. “Beyond Film.” Bulletin of the American Society for Information
Science 7, no. 1 (October, 1980).

Orlon
Orlon
The invention: A synthetic fiber made from polyacrylonitrile that
has become widely used in textiles and in the preparation of
high-strength carbon fibers.
The people behind the invention:
Herbert Rein (1899-1955), a German chemist
Ray C. Houtz (1907- ), an American chemist
A Difficult Plastic
541
“Polymers” are large molecules that are made up of chains of
many smaller molecules, called “monomers.” Materials that are
made of polymers are also called polymers, and some polymers,
such as proteins, cellulose, and starch, occur in nature. Most polymers,
however, are synthetic materials, which means that they were
created by scientists.
The twenty-year period beginning in 1930 was the age of great
discoveries in polymers by both chemists and engineers. During
this time, many of the synthetic polymers, which are also known as
plastics, were first made and their uses found. Among these polymers
were nylon, polyester, and polyacrylonitrile. The last of these
materials, polyacrylonitrile (PAN), was first synthesized by German
chemists in the late 1920’s. They linked more than one thousand
of the small, organic molecules of acrylonitrile to make a polymer.
The polymer chains of this material had the properties that
were needed to form strong fibers, but there was one problem. Instead
of melting when heated to a high temperature, PAN simply
decomposed. This made it impossible, with the technology that existed
then, to make fibers.
The best method available to industry at that time was the process
of melt spinning, in which fibers were made by forcing molten
polymer through small holes and allowing it to cool. Researchers realized
that, if PAN could be put into a solution, the same apparatus
could be used to spin PAN fibers. Scientists in Germany and the
United States tried to find a solvent or liquid that would dissolve
PAN, but they were unsuccessful until World War II began.

542 / Orlon
Fibers for War
In 1938, the German chemist Walter Reppe developed a new
class of organic solvents called “amides.” These new liquids were
able to dissolve many materials, including some of the recently discovered
polymers. When World War II began in 1940, both the Germans
and the Allies needed to develop new materials for the war effort.
Materials such as rubber and fibers were in short supply. Thus,
there was increased governmental support for chemical and industrial
research on both sides of the war. This support was to result in
two independent solutions to the PAN problem.
In 1942, Herbert Rein, while working for I. G. Farben in Germany,
discovered that PAN fibers could be produced from a solution of
polyacrylonitrile dissolved in the newly synthesized solvent dimethylformamide.
At the same time Ray C. Houtz, who was working for E.
I. Du Pont de Nemours in Wilmington, Delaware, found that the related
solvent dimethylacetamide would also form excellent PAN fibers.
His work was patented, and some fibers were produced for use
by the military during the war. In 1950, Du Pont began commercial
production of a form of polyacrylonitrile fibers called Orlon. The
Monsanto Company followed with a fiber called Acrilon in 1952, and
other companies began to make similar products in 1958.
There are two ways to produce PAN fibers. In both methods,
polyacrylonitrile is first dissolved in a suitable solvent. The solution
is next forced through small holes in a device called a “spinneret.”
The solution emerges from the spinneret as thin streams of a thick,
gooey liquid. In the “wet spinning method,” the streams then enter
another liquid (usually water or alcohol), which extracts the solvent
from the solution, leaving behind the pure PAN fiber. After air drying,
the fiber can be treated like any other fiber. The “dry spinning
method” uses no liquid. Instead, the solvent is evaporated from the
emerging streams by means of hot air, and again the PAN fiber is left
behind.
In 1944, another discovery was made that is an important part of
the polyacrylonitrile fiber story. W. P. Coxe of Du Pont and L. L.
Winter at Union Carbide Corporation found that, when PAN fibers
are heated under certain conditions, the polymer decomposes and
changes into graphite (one of the elemental forms of carbon) but still

keeps its fiber form. In contrast to most forms of graphite, these fibers
were exceptionally strong. These were the first carbon fibers
ever made. Originally known as “black Orlon,” they were first produced
commercially by the Japanese in 1964, but they were too
weak to find many uses. After new methods of graphitization were
developed jointly by labs in Japan, Great Britain, and the United
States, the strength of the carbon fibers was increased, and the fibers
began to be used in many fields.
Impact
Orlon / 543
As had been predicted earlier, PAN fibers were found to have
some very useful properties. Their discovery and commercialization
helped pave the way for the acceptance and wide use of polymers.
The fibers derive their properties from the stiff, rodlike structure
of polyacrylonitrile. Known as acrylics, these fibers are more
durable than cotton, and they are the best alternative to wool for
sweaters. Acrylics are resistant to heat and chemicals, can be dyed
easily, resist fading or wrinkling, and are mildew-resistant. Thus, after
their introduction, PAN fibers were very quickly made into
yarns, blankets, draperies, carpets, rugs, sportswear, and various
items of clothing. Often, the fibers contain small amounts of other
polymers that give them additional useful properties.
A significant amount of PAN fiber is used in making carbon fibers.
These lightweight fibers are stronger for their weight than any
known material, and they are used to make high-strength composites
for applications in aerospace, the military, and sports. A “fiber
composite” is a material made from two parts: a fiber, such as carbon
or glass, and something to hold the fibers together, which is
usually a plastic called an “epoxy.” Fiber composites are used in
products that require great strength and light weight. Their applications
can be as ordinary as a tennis racket or fishing pole or as exotic
as an airplane tail or the body of a spacecraft.
See also Buna rubber; Neoprene; Nylon; Plastic; Polyester; Polyethylene;
Polystyrene.

544 / Orlon
Further Reading
Handley, Susannah. Nylon: The Story of a Fashion Revolution: A Celebration
of Design from Art Silk to Nylon and Thinking Fibres. Baltimore:
Johns Hopkins University Press, 1999.
Hunter, David. “Du Pont Bids Adieu to Acrylic Fibers.” Chemical
Week 146, no. 24 (June 20, 1990).
Kornheiser, Tony. “So Long, Orlon.” Washington Post (June 13, 1990).
Seymour, Raymond Benedict, and Roger Stephen Porter. Manmade
Fibers: Their Origin and Development. New York: Elsevier Applied
Science, 1993.

Pacemaker
Pacemaker
The invention: A small device using transistor circuitry that regulates
the heartbeat of the patient in whom it is surgically emplaced.
The people behind the invention:
Ake Senning (1915- ), a Swedish physician
Rune Elmquist, co-inventor of the first pacemaker
Paul Maurice Zoll (1911- ), an American cardiologist
Cardiac Pacing
545
The fundamentals of cardiac electrophysiology (the electrical activity
of the heart) were determined during the eighteenth century;
the first successful cardiac resuscitation by electrical stimulation occurred
in 1774. The use of artificial pacemakers for resuscitation was
demonstrated in 1929 by Mark Lidwell. Lidwell and his coworkers
developed a portable apparatus that could be connected to a power
source. The pacemaker was used successfully on several stillborn
infants after other methods of resuscitation failed. Nevertheless,
these early machines were unreliable.
Ake Senning’s first experience with the effect of electrical stimulation
on cardiac physiology was memorable; grasping a radio
ground wire, Senning felt a brief episode of ventricular arrhythmia
(irregular heartbeat). Later, he was able to apply a similar electrical
stimulation to control a heartbeat during surgery.
The principle of electrical regulation of the heart was valid. It was
shown that pacemakers introduced intravenously into the sinus
node area of a dog’s heart could be used to control the heartbeat
rate. Although Paul Maurice Zoll utilized a similar apparatus in
several patients with cardiac arrhythmia, it was not appropriate for
extensive clinical use; it was large and often caused unpleasant sensations
or burns. In 1957, however, Ake Senning observed that attaching
stainless steel electrodes to a child’s heart made it possible
to regulate the heart’s rate of contraction. Senning considered this to
represent the beginning of the era of clinical pacing.

546 / Pacemaker
Development of Cardiac Pacemakers
Senning’s observations of the successful use of the cardiac pacemaker
had allowed him to identify the problems inherent in the device.
He realized that the attachment of the device to the lower, ventricular
region of the heart made possible more reliable control, but
other problems remained unsolved. It was inconvenient, for example,
to carry the machine externally; a cord was wrapped around the
patient that allowed the pacemaker to be recharged, which had to be
done frequently. Also, for unknown reasons, heart resistance would
increase with use of the pacemaker, which meant that increasingly
large voltages had to be used to stimulate the heart. Levels as high
as 20 volts could cause quite a “start” in the patient. Furthermore,
there was a continuous threat of infection.
In 1957, Senning and his colleague Rune Elmquist developed a
pacemaker that was powered by rechargeable nickel-cadmium batteries,
which had to be recharged once a month. Although Senning
and Elmquist did not yet consider the pacemaker ready for human
testing, fate intervened. Aforty-three-year-old man was admitted to
the hospital suffering from an atrioventricular block, an inability of
the electrical stimulus to travel along the conductive fibers of the
“bundle of His” (a band of cardiac muscle fibers). As a result of this
condition, the patient required repeated cardiac resuscitation. Similar
types of heart block were associated with a mortality rate higher
than 50 percent per year and nearly 95 percent over five years.
Senning implanted two pacemakers (one failed) into the myocardium
of the patient’s heart, one of which provided a regulatory
rate of 64 beats per minute. Although the pacemakers required periodic
replacement, the patient remained alive and active for twenty
years. (He later became president of the Swedish Association for
Heart and Lung Disease.)
During the next five years, the development of more reliable and
more complex pacemakers continued, and implanting the pacemaker
through the vein rather than through the thorax made it simpler
to use the procedure. The first pacemakers were of the “asynchronous”
type, which generated a regular charge that overrode the
natural pacemaker in the heart. The rate could be set by the physician
but could not be altered if the need arose. In 1963, an atrial-

triggered synchronous pacemaker was installed by a Swedish team.
The advantage of this apparatus lay in its ability to trigger a heart
contraction only when the normal heart rhythm was interrupted.
Most of these pacemakers contained a sensing device that detected
the atrial impulse and generated an electrical discharge only when
the heart rate fell below 68 to 72 beats per minute.
The biggest problems during this period lay in the size of the
pacemaker and the short life of the battery. The expiration of the
electrical impulse sometimes caused the death of the patient. In addition,
the most reliable method of checking the energy level of the
battery was to watch for a decreased pulse rate. As improvements
were made in electronics, the pacemaker became smaller, and in
1972, the more reliable lithium-iodine batteries were introduced.
These batteries made it possible to store more energy and to monitor
the energy level more effectively. The use of this type of power
source essentially eliminated the battery as the limiting factor in the
longevity of the pacemaker. The period of time that a pacemaker
could operate continuously in the body increased from a period of
days in 1958 to five to ten years by the 1970’s.
Consequences
Pacemaker / 547
The development of electronic heart pacemakers revolutionized
cardiology. Although the initial machines were used primarily to
control cardiac bradycardia, the often life-threatening slowing of
the heartbeat, a wide variety of arrhythmias and problems with cardiac
output can now be controlled through the use of these devices.
The success associated with the surgical implantation of pacemakers
is attested by the frequency of its use. Prior to 1960, only three
pacemakers had been implanted. During the 1990’s, however, some
300,000 were implanted each year throughout the world. In the
United States, the prevalence of implants is on the order of 1 per
1,000 persons in the population.
Pacemaker technology continues to improve. Newer models can
sense pH and oxygen levels in the blood, as well as respiratory rate.
They have become further sensitized to minor electrical disturbances
and can adjust accordingly. The use of easily sterilized circuitry
has eliminated the danger of infection. Once the pacemaker

548 / Pacemaker
has been installed in the patient, the basic electronics require no additional
attention. With the use of modern pacemakers, many forms
of electrical arrhythmias need no longer be life-threatening.
See also Artificial heart; Contact lenses; Coronary artery bypass
surgery; Electrocardiogram; Hearing aid; Heart-lung machine.
Further Reading
Bigelow, W. G. Cold Hearts: The Story of Hypothermia and the Pacemaker
in Heart Surgery. Toronto: McClelland and Stewart, 1984.
Greatbatch, Wilson. The Making of the Pacemaker: Celebrating a Lifesaving
Invention. Amherst, N.Y.: Prometheus Books, 2000.
“The Pacemaker.” Newsweek 130, no. 24A (Winter, 1997/1998).
Thalen, H. J. The Artificial Cardiac Pacemaker: Its History, Development
and Clinical Application. London: Heinemann Medical, 1969.

Pap test
Pap test
The invention: A cytologic technique the diagnosing uterine cancer,
the second most common fatal cancer in American women.
The people behind the invention:
George N. Papanicolaou (1883-1962), a Greek-born American
physician and anatomist
Charles Stockard (1879-1939), an American anatomist
Herbert Traut (1894-1972), an American gynecologist
Cancer in History
549
Cancer, first named by the ancient Greek physician Hippocrates
of Cos, is one of the most painful and dreaded forms of human disease.
It occurs when body cells run wild and interfere with the normal
activities of the body. The early diagnosis of cancer is extremely
important because early detection often makes it possible to effect
successful cures. The modern detection of cancer is usually done by
the microscopic examination of the cancer cells, using the techniques
of the area of biology called “cytology, ” or cell biology.
Development of cancer cytology began in 1867, after L. S. Beale
reported tumor cells in the saliva from a patient who was afflicted
with cancer of the pharynx. Beale recommended the use in cancer
detection of microscopic examination of cells shed or removed (exfoliated)
from organs including the digestive, the urinary, and the
reproductive tracts. Soon, other scientists identified numerous striking
differences, including cell size and shape, the size of cell nuclei,
and the complexity of cell nuclei.
Modern cytologic detection of cancer evolved from the work of
George N. Papanicolaou, a Greek physician who trained at the University
of Athens Medical School. In 1913, he emigrated to the
United States.
In 1917, he began studying sex determination of guinea pigs with
Charles Stockard at New York’s Cornell Medical College. Papanicolaou’s
efforts required him to obtain ova (egg cells) at a precise
period in their maturation cycle, a process that required an indicator

550 / Pap test
of the time at which the animals ovulated. In search of this indicator,
Papanicolaou designed a method that involved microscopic examination
of the vaginal discharges from female guinea pigs.
Initially, Papanicolaou sought traces of blood, such as those
seen in the menstrual discharges from both primates and humans.
Papanicolaou found no blood in the guinea pig vaginal discharges.
Instead, he noticed changes in the size and the shape of the uterine
cells shed in these discharges. These changes recurred in a fifteento-sixteen-day
cycle that correlated well with the guinea pig menstrual
cycle.
“New Cancer Detection Method”
Papanicolaou next extended his efforts to the study of humans.
This endeavor was designed originally to identify whether comparable
changes in the exfoliated cells of the human vagina occurred
in women. Its goal was to gain an understanding of the human menstrual
cycle. In the course of this work, Papanicolaou observed distinctive
abnormal cells in the vaginal fluid from a woman afflicted
with cancer of the cervix. This led him to begin to attempt to develop
a cytologic method for the detection of uterine cancer, the second
most common type of fatal cancer in American women of the
time.
In 1928, Papanicolaou published his cytologic method of cancer
detection in the Proceedings of the Third Race Betterment Conference,
held in Battle Creek, Michigan. The work was received well by the
news media (for example, the January 5, 1928, New York World credited
him with a “new cancer detection method”). Nevertheless, the
publication—and others he produced over the next ten years—was
not very interesting to gynecologists of the time. Rather, they preferred
use of the standard methodology of uterine cancer diagnosis
(cervical biopsy and curettage).
Consequently, in 1932, Papanicolaou turned his energy toward
studying human reproductive endocrinology problems related to
the effects of hormones on cells of the reproductive system. One example
of this work was published in a 1933 issue of The American
Journal of Anatomy, where he described “the sexual cycle in the human
female.” Other such efforts resulted in better understanding of

eproductive problems that include amenorrhea and menopause.
It was not until Papanicolaou’s collaboration with gynecologist
Herbert Traut (beginning in 1939), which led to the publication of
Diagnosis of Uterine Cancer by the Vaginal Smear (1943), that clinical
acceptance of the method began to develop. Their monograph documented
an impressive, irrefutable group of studies of both normal
and disease states that included nearly two hundred cases of cancer
of the uterus.
Soon, many other researchers began to confirm these findings;
by 1948, the newly named American Cancer Society noted that the
“Pap” smear seemed to be a very valuable tool for detecting vaginal
cancer. Wide acceptance of the Pap test followed, and, beginning
in 1947, hundreds of physicians from all over the world
flocked to Papanicolaou’s course on the subject. They learned his
smear/diagnosis techniques and disseminated them around the
world.
Impact
Pap test / 551
The Pap test has been cited by many physicians as being the most
significant and useful modern discovery in the field of cancer research.
One way of measuring its impact is the realization that the
test allows the identification of uterine cancer in the earliest stages,
long before other detection methods can be used. Moreover, because
of resultant early diagnosis, the disease can be cured in more
than 80 percent of all cases identified by the test. In addition, Pap
testing allows the identification of cancer of the uterine cervix so
early that its cure rate can be nearly 100 percent.
Papanicolaou extended the use of the smear technique from
examination of vaginal discharges to diagnosis of cancer in many
other organs from which scrapings, washings, and discharges
can be obtained. These tissues include the colon, the kidney, the
bladder, the prostate, the lung, the breast, and the sinuses. In
most cases, such examination of these tissues has made it possible
to diagnose cancer much sooner than is possible by using
other existing methods. As a result, the smear method has become
a basis of cancer control in national health programs throughout the
world.

552 / Pap test
See also Amniocentesis; Birth control pill; Mammography;
Syphilis test; Ultrasound.
Further Reading
Apgar, Barbara, Lawrence L. Gabel, and Robert T. Brown. Oncology.
Philadelphia: W. B. Saunders, 1998.
Entman, Stephen S., and Charles B. Rush. Office Gynecology. Philadelphia:
Saunders, 1995.
Glass, Robert H., Michèle G. Curtis, and Michael P. Hopkins. Glass’s
Office Gynecology. 5th ed. Baltimore: Williams & Wilkins, 1999.
Rushing, Lynda, and Nancy Joste. Abnormal Pap Smears: What Every
Woman Needs to Know. Amherst, N.Y.: Prometheus Books, 2001.

Penicillin
Penicillin
The invention: The first successful and widely used antibiotic
drug, penicillin has been called the twentieth century’s greatest
“wonder drug.”
The people behind the invention:
Sir Alexander Fleming (1881-1955), a Scottish bacteriologist,
cowinner of the 1945 Nobel Prize in Physiology or Medicine
Baron Florey (1898-1968), an Australian pathologist, cowinner
of the 1945 Nobel Prize in Physiology or Medicine
Ernst Boris Chain (1906-1979), an émigré German biochemist,
cowinner of the 1945 Nobel Prize in Physiology or Medicine
The Search for the Perfect Antibiotic
553
During the early twentieth century, scientists were aware of antibacterial
substances but did not know how to make full use of them
in the treatment of diseases. Sir Alexander Fleming discovered penicillin
in 1928, but he was unable to duplicate his laboratory results
of its antibiotic properties in clinical tests; as a result, he did not recognize
the medical potential of penicillin. Between 1935 and 1940,
penicillin was purified, concentrated, and clinically tested by pathologist
Baron Florey, biochemist Ernst Boris Chain, and members
of their Oxford research group. Their achievement has since been regarded
as one of the greatest medical discoveries of the twentieth
century.
Florey was a professor at Oxford University in charge of the Sir
William Dunn School of Pathology. Chain had worked for two years
at Cambridge University in the laboratory of Frederick Gowland
Hopkins, an eminent chemist and discoverer of vitamins. Hopkins
recommended Chain to Florey, who was searching for a candidate
to lead a new biochemical unit in the Dunn School of Pathology.
In 1938, Florey and Chain formed a research group to investigate
the phenomenon of antibiosis, or the antagonistic association between
different forms of life. The union of Florey’s medical knowledge
and Chain’s biochemical expertise proved to be an ideal com-

554 / Penicillin
bination for exploring the antibiosis potential of penicillin. Florey
and Chain began their investigation with a literature search in
which Chain came across Fleming’s work and added penicillin to
their list of potential antibiotics.
Their first task was to isolate pure penicillin from a crude liquid
extract. A culture of Fleming’s original Penicillium notatum was
maintained at Oxford and was used by the Oxford group for penicillin
production. Extracting large quantities of penicillin from the
medium was a painstaking task, as the solution contained only one
part of the antibiotic in ten million. When enough of the raw juice
was collected, the Oxford group focused on eliminating impurities
and concentrating the penicillin. The concentrated liquid was then
freeze-dried, leaving a soluble brown powder.
Spectacular Results
In May, 1940, Florey’s clinical tests of the crude penicillin proved
its value as an antibiotic. Following extensive controlled experiments
with mice, the Oxford group concluded that they had discovered
an antibiotic that was nontoxic and far more effective against
pathogenic bacteria than any of the known sulfa drugs. Furthermore,
penicillin was not inactivated after injection into the bloodstream
but was excreted unchanged in the urine. Continued tests
showed that penicillin did not interfere with white blood cells and
had no adverse effect on living cells. Bacteria susceptible to the antibiotic
included those responsible for gas gangrene, pneumonia,
meningitis, diphtheria, and gonorrhea. American researchers later
proved that penicillin was also effective against syphilis.
In January, 1941, Florey injected a volunteer with penicillin
and found that there were no side effects to treatment with the
antibiotic. In February, the group began treatment of Albert Alexander,
a forty-three-year-old policeman with a serious staphylococci
and streptococci infection that was resisting massive doses of
sulfa drugs. Alexander had been hospitalized for two months after
an infection in the corner of his mouth had spread to his face,
shoulder, and lungs. After receiving an injection of 200 milligrams
of penicillin, Alexander showed remarkable progress, and for the
next ten days his condition improved. Unfortunately, the Oxford

Sir Alexander Fleming
Penicillin / 555
In 1900 Alexander Fleming (1881-1955) enlisted in the London
Scottish Regiment, hoping to see action in the South African
(Boer) War then underway between Great Britain and South
Africa’s independent Afrikaner republics. However, the war
ended too soon for him. So, having come into a small inheritance,
he decided to become a physician instead. Accumulating
honors and prizes along the way, he succeeded and became a
fellow of the Royal College of Surgeons of England in 1909.
His mentor was Sir Almroth Wright. Fleming assisted him at
St. Mary’s Hospital in Paddington, and they were at the forefront
of the burgeoning field of bacteriology. They were, for example,
among the first to treat syphilis with the newly discovered
Salvarsan, and they championed immunization through
vaccination. With the outbreak of World War I, Fleming followed
Wright into the Royal Army Medical Corps, conducting
research on battlefield wounds at a laboratory near Boulogne.
The infections Fleming inspected horrified him. After the war,
again at St. Mary’s Hospital, he dedicated himself to finding
anti-bacterial agents.
He succeed twice: “lysozyme” in 1921 and penicillin in 1928.
To his great disappointment, he was unable to produce pure,
potent concentrations of the drug. That had to await the work of
Ernst Chain and Howard Florey in 1940. Meanwhile, Fleming
studied the antibacterial properties of sulfa drugs. He was overjoyed
that Chain and Florey succeeded where he had failed and
that penicillin saved lives during World War II and afterward,
but he was taken aback when with them he began to receive a
stream of tributes, awards, decorations, honorary degrees, and
fellowships, including the Nobel Prize in Physiology or Medicine
in 1945. He was by nature a reserved man.
However, he adjusted to his role as one of the most lionized
medical researchers of his generation and continued his work,
both as a professor of medicine at the University of London from
1928 until 1948 and as director of the same St. Mary’s Hospital
laboratory where he had started his career (renamed the Wright-
Fleming Institute in 1948). He died soon after he retired in 1955.

556 / Penicillin
production facility was unable to generate enough penicillin to
overcome Alexander’s advanced infection completely, and he died
on March 15. A later case involving a fourteen-year-old boy with
staphylococcal septicemia and osteomyelitis had a more spectacular
result: The patient made a complete recovery in two months. In
all the early clinical treatments, patients showed vast improvement,
and most recovered completely from infections that resisted
all other treatment.
Impact
Penicillin is among the greatest medical discoveries of the twentieth
century. Florey and Chain’s chemical and clinical research
brought about a revolution in the treatment of infectious disease.
Almost every organ in the body is vulnerable to bacteria. Before
penicillin, the only antimicrobial drugs available were quinine, arsenic,
and sulfa drugs. Of these, only the sulfa drugs were useful for
treatment of bacterial infection, but their high toxicity often limited
their use. With this small arsenal, doctors were helpless to treat
thousands of patients with bacterial infections.
The work of Florey and Chain achieved particular attention because
of World War II and the need for treatments of such scourges
as gas gangrene, which had infected the wounds of numerous
World War I soldiers. With the help of Florey and Chain’s Oxford
group, scientists at the U.S. Department of Agriculture’s Northern
Regional Research Laboratory developed a highly efficient method
for producing penicillin using fermentation. After an extended search,
scientists were also able to isolate a more productive penicillin
strain, Penicillium chrysogenum. By 1945, a strain was developed that
produced five hundred times more penicillin than Fleming’s original
mold had.
Penicillin, the first of the “wonder drugs,” remains one of the
most powerful antibiotic in existence. Diseases such as pneumonia,
meningitis, and syphilis are still treated with penicillin. Penicillin
and other antibiotics also had a broad impact on other fields of medicine,
as major operations such as heart surgery, organ transplants,
and management of severe burns became possible once the threat of
bacterial infection was minimized.

Florey and Chain received numerous awards for their achievement,
the greatest of which was the 1945 Nobel Prize in Physiology
or Medicine, which they shared with Fleming for his original discovery.
Florey was among the most effective medical scientists of
his generation, and Chain earned similar accolades in the science of
biochemistry. This combination of outstanding medical and chemical
expertise made possible one of the greatest discoveries in human
history.
See also Antibacterial drugs; Artificial hormone; Genetically engineered
insulin; Polio vaccine (Sabin); Polio vaccine (Salk); Reserpine;
Salvarsan; Tuberculosis vaccine; Typhus vaccine; Yellow fever
vaccine.
Further Reading
Penicillin / 557
Bickel, Lennard. Florey, The Man Who Made Penicillin. Carlton South,
Victoria, Australia: Melbourne University Press, 1995.
Clark, Ronald William. The Life of Ernst Chain: Penicillin and Beyond.
New York: St. Martin’s Press, 1985.
Hughes, William Howard. Alexander Fleming and Penicillin. Hove:
Wayland, 1979.
Mateles, Richard I. Penicillin: A Paradigm for Biotechnology. Chicago:
Canadida Corporation, 1998.

558
Personal computer
Personal computer
The invention: Originally a tradename of the IBM Corporation,
“personal computer” has become a generic term for increasingly
powerful desktop computing systems using microprocessors.
The people behind the invention:
Tom J. Watson, (1874-1956), the founder of IBM, who set
corporate philosophy and marketing principles
Frank Cary (1920- ), the chief executive officer of IBM at the
time of the decision to market a personal computer
John Opel (1925- ), a member of the Corporate Management
Committee
George Belzel, a member of the Corporate Management
Committee
Paul Rizzo, a member of the Corporate Management Committee
Dean McKay (1921- ), a member of the Corporate
Management Committee
William L. Sydnes, the leader of the original twelve-member
design team
Shaking up the System
For many years, the International Business Machines (IBM) Corporation
had been set in its ways, sticking to traditions established
by its founder, Tom Watson, Sr. If it hoped to enter the new microcomputer
market, however, it was clear that only nontraditional
methods would be useful. Apple Computer was already beginning
to make inroads into large IBM accounts, and IBM stock was starting
to stagnate on Wall Street. A 1979 Business Week article asked: “Is
IBM just another stodgy, mature company?” The microcomputer
market was expected to grow more than 40 percent in the early
1980’s, but IBM would have to make some changes in order to bring
a competitive personal computer (PC) to the market.
The decision to build and market the PC was made by the company’s
Corporate Management Committee (CMC). CMC members
included chief executive officer Frank Cary, John Opel, George

Belzel, Paul Rizzo, Dean McKay, and three senior vice presidents. In
July of 1980, Cary gave the order to proceed. He wanted the PC to be
designed and built within a year. The CMC approved the initial design
of the PC one month later. Twelve engineers, with William L.
Sydnes as their leader, were appointed as the design team. At the
end of 1980, the team had grown to 150.
Most parts of the PC had to be produced outside IBM. Microsoft
Corporation won the contract to produce the PC’s disk operating system
(DOS) and the BASIC (Beginner’s All-purpose Symbolic Instruction
Code) language that is built into the PC’s read-only memory
(ROM). Intel Corporation was chosen to make the PC’s central processing
unit (CPU) chip, the “brains” of the machine. Outside programmers
wrote software for the PC. Ten years earlier, this strategy
would have been unheard of within IBM since all aspects of manufacturing,
service, and repair were traditionally taken care of in-house.
Marketing the System
Personal computer / 559
IBM hired a New York firm to design a media campaign for the
new PC. Readers of magazines and newspapers saw the character
of Charlie Chaplin advertising the new PC. The machine was delivered
on schedule on August 12, 1981. The price of the basic “system
unit” was $1,565. A system with 64 kilobytes of random access
memory (RAM), a 13-centimeter single-sided disk drive holding
160 kilobytes, and a monitor was priced at about $3,000. A system
with color graphics, a second disk drive, and a dot matrix printer
cost about $4,500.
Many useful computer programs had been adapted to the PC
and were available when it was introduced. VisiCalc from Personal
Software—the program that is credited with “making” the microcomputer
revolution—was one of the first available. Other packages
included a comprehensive accounting system by Peachtree
Software and a word processing package called Easywriter by Information
Unlimited Software.
As the selection of software grew, so did sales. In the first year after
its introduction, the IBM PC went from a zero market share to 28
percent of the market. Yet the credit for the success of the PC does
not go to IBM alone. Many hundreds of companies were able to pro-

560 / Personal computer
duce software and hardware for the PC. Within two years, powerful
products such as Lotus Corporation’s 1-2-3 business spreadsheet
had come to the market. Many believed that Lotus 1-2-3 was the
program that caused the PC to become so phenomenally successful.
Other companies produced hardware features (expansion boards)
that increased the PC’s memory storage or enabled the machine to
“drive” audiovisual presentations such as slide shows. Business especially
found the PC to be a powerful tool. The PC has survived because
of its expansion capability.
IBM has continued to upgrade the PC. In 1983, the PC/XT was
introduced. It had more expansion slots and a fixed disk offering 10
million bytes of storage for programs and data. Many of the companies
that made expansion boards found themselves able to make
whole PCs. An entire range of PC-compatible systems was introduced
to the market, many offering features that IBM did not include
in the original PC. The original PC has become a whole family
of computers, sold by both IBM and other companies. The hardware
and software continue to evolve; each generation offers more computing
power and storage with a lower price tag.
Consequences
IBM’s entry into the microcomputer market gave microcomputers
credibility. Apple Computer’s earlier introduction of its computer
did not win wide acceptance with the corporate world. Apple
did, however, thrive within the educational marketplace. IBM’s
name already carried with it much clout, because IBM was a successful
company. Apple Computer represented all that was great
about the “new” microcomputer, but the IBM PC benefited from
IBM’s image of stability and success.
IBM coined the term personal computer and its acronym PC. The
acronym PC is now used almost universally to refer to the microcomputer.
It also had great significance with users who had previously
used a large mainframe computer that had to be shared with
the whole company. This was their personal computer. That was important
to many PC buyers, since the company mainframe was perceived
as being complicated and slow. The PC owner now had complete
control.

See also Apple II computer; BINAC computer; Colossus computer;
ENIAC computer; Floppy disk; Hard disk; IBM Model 1401
computer; Internet; Supercomputer; UNIVAC computer.
Further Reading
Personal computer / 561
Cerruzi, Paul E. A History of Modern Computing. Cambridge, Mass.:
MIT Press, 2000.
Chposky, James, and Ted Leonsis. Blue Magic: The People, Power, and
Politics Behind the IBM Personal Computer. New York: Facts on File,
1988.
Freiberger, Paul, and Michael Swaine. Fire in the Valley: The Making of
the Personal Computer. New York: McGraw-Hill, 2000.
Grossman. Wendy. Remembering the Future: Interviews from Personal
Computer World. New York: Springer, 1997.

562
Photoelectric cell
Photoelectric cell
The invention: The first devices to make practical use of the photoelectric
effect, photoelectric cells were of decisive importance in
the electron theory of metals.
The people behind the invention:
Julius Elster (1854-1920), a German experimental physicist
Hans Friedrich Geitel (1855-1923), a German physicist
Wilhelm Hallwachs (1859-1922), a German physicist
Early Photoelectric Cells
The photoelectric effect was known to science in the early
nineteenth century when the French physicist Alexandre-Edmond
Becquerel wrote of it in connection with his work on glass-enclosed
primary batteries. He discovered that the voltage of his batteries increased
with intensified illumination and that green light produced
the highest voltage. Since Becquerel researched batteries exclusively,
however, the liquid-type photocell was not discovered until
1929, when the Wein and Arcturus cells were introduced commercially.
These cells were miniature voltaic cells arranged so that light
falling on one side of the front plate generated a considerable
amount of electrical energy. The cells had short lives, unfortunately;
when subjected to cold, the electrolyte froze, and when subjected to
heat, the gas generated would expand and explode the cells.
What came to be known as the photoelectric cell, a device connecting
light and electricity, had its beginnings in the 1880’s. At
that time, scientists noticed that a negatively charged metal plate
lost its charge much more quickly in the light (especially ultraviolet
light) than in the dark. Several years later, researchers demonstrated
that this phenomenon was not an “ionization” effect because
of the air’s increased conductivity, since the phenomenon
took place in a vacuum but did not take place if the plate were positively
charged. Instead, the phenomenon had to be attributed to
the light that excited the electrons of the metal and caused them to
fly off: A neutral plate even acquired a slight positive charge under

the influence of strong light. Study of this effect not only contributed
evidence to an electronic theory of matter—and, as a result of
some brilliant mathematical work by the physicist Albert Einstein,
later increased knowledge of the nature of radiant energy—but
also further linked the studies of light and electricity. It even explained
certain chemical phenomena, such as the process of photography.
It is important to note that all the experimental work on
photoelectricity accomplished prior to the work of Julius Elster
and Hans Friedrich Geitel was carried out before the existence of
the electron was known.
Explaining Photoelectric Emission
Photoelectric cell / 563
After the English physicist Sir Joseph John Thomson’s discovery
of the electron in 1897, investigators soon realized that the photoelectric
effect was caused by the emission of electrons under the influence
of radiation. The fundamental theory of photoelectric emission
was put forward by Einstein in 1905 on the basis of the German
physicist Max Planck’s quantum theory (1900). Thus, it was not surprising
that light was found to have an electronic effect. Since it was
known that the longer radio waves could shake electrons into resonant
oscillations and the shorter X rays could detach electrons from
the atoms of gases, the intermediate waves of visual light would
have been expected to have some effect upon electrons—such as detaching
them from metal plates and therefore setting up a difference
of potential. The photoelectric cell, developed by Elster and Geitel
in 1904, was a practical device that made use of this effect.
In 1888, Wilhelm Hallwachs observed that an electrically charged
zinc electrode loses its charge when exposed to ultraviolet radiation
if the charge is negative, but is able to retain a positive charge under
the same conditions. The following year, Elster and Geitel discovered
a photoelectric effect caused by visible light; however, they
used the alkali metals potassium and sodium for their experiments
instead of zinc.
The Elster-Geitel photocell (a vacuum emission cell, as opposed to
a gas-filled cell) consisted of an evacuated glass bulb containing two
electrodes. The cathode consisted of a thin film of a rare, chemically
active metal (such as potassium) that lost its electrons fairly readily;

564 / Photoelectric cell
Julius Elster and Hans Geitel
Nicknamed the Castor and Pollux of physics after the twins
of Greek mythology, Johann Philipp Ludwig Julius Elster and
Hans Friedrich Geitel were among the most productive teams
in the history of science. Elster, born in 1854, and Geitel, born in
1855, met in 1875 while attending university in Heidelberg,
Germany. Graduate studies took them to separate cities, but
then in 1881 they were together again as mathematics and physics
teachers at Herzoglich Gymnasium in Wolfenbüttel. In 1884
they began their scientific collaboration, which lasted more
than thirty years and produced more than 150 reports.
Essentially experimentalists, they investigated phenomena
that were among the greatest mysteries of the times. Their first
works concerned the electrification of flames and the electrical
properties of thunderstorms. They went on to study the photoelectric
effect, thermal electron emission, practical uses for photocells,
and Becquerel rays in the earth and air. They developed a
method for measuring electrical phenomena in gases that remained
the standard for the following forty years.
Their greatest achievements, however, lay with radioactivity
and radiation. Their demonstration that incandescent filaments
emitted “negative electricity” proved beyond doubt that
electrons, which J. J. Thomson had recently claimed to have detected,
did in fact exist. They also proved that radioactivity,
such as that from uranium, came wholly from within the atom,
not from environmental influences. Ernest Rutherford, the great
English physicist, said in 1913 that Elster and Geitel had contributed
more to the understanding of terrestrial and atmospheric
radioactivity than anyone else.
The pair were practically inseparable until Elster died in
1920. Geitel died three years later.
the anode was simply a wire sealed in to complete the circuit. This anode
was maintained at a positive potential in order to collect the negative
charges released by light from the cathode. The Elster-Geitel
photocell resembled two other types of vacuum tubes in existence at
the time: the cathode-ray tube, in which the cathode emitted electrons
under the influence of a high potential, and the thermionic
valve (a valve that permits the passage of current in one direction

only), in which it emitted electrons under the influence of heat. Like
both of these vacuum tubes, the photoelectric cell could be classified
as an “electronic” device.
The new cell, then, emitted electrons when stimulated by light, and
at a rate proportional to the intensity of the light. Hence, a current
could be obtained from the cell. Yet Elster and Geitel found that their
photoelectric currents fell off gradually; they therefore spoke of “fatigue”
(instability). It was discovered later that most of this change was
not a direct effect of a photoelectric current’s passage; it was not even
an indirect effect but was caused by oxidation of the cathode by the air.
Since all modern cathodes are enclosed in sealed vessels, that source of
change has been completely abolished. Nevertheless, the changes that
persist in modern cathodes often are indirect effects of light that can be
produced independently of any photoelectric current.
Impact
Photoelectric cell / 565
The Elster-Geitel photocell was, for some twenty years, used in
all emission cells adapted for the visible spectrum, and throughout
the twentieth century, the photoelectric cell has had a wide variety
of applications in numerous fields. For example, if products leaving
a factory on a conveyor belt were passed between a light and a cell,
they could be counted as they interrupted the beam. Persons entering
a building could be counted also, and if invisible ultraviolet rays
were used, those persons could be detected without their knowledge.
Simple relay circuits could be arranged that would automatically
switch on street lamps when it grew dark. The sensitivity of
the cell with an amplifying circuit enabled it to “see” objects too
faint for the human eye, such as minor stars or certain lines in the
spectra of elements excited by a flame or discharge. The fact that the
current depended on the intensity of the light made it possible to
construct photoelectric meters that could judge the strength of illumination
without risking human error—for example, to determine
the right exposure for a photograph.
A further use for the cell was to make talking films possible. The
early “talkies” had depended on gramophone records, but it was very
difficult to keep the records in time with the film. Now, the waves of
speech and music could be recorded in a “sound track” by turning the

566 / Photoelectric cell
sound first into current through a microphone and then into light with
a neon tube or magnetic shutter; next, the variations in the intensity of
this light on the side of the film were photographed. By reversing the
process and running the film between a light and a photoelectric cell,
the visual signals could be converted back to sound.
See also Alkaline storage battery; Photovoltaic cell; Solar thermal
engine.
Further Reading
Hoberman, Stuart. Solar Cell and Photocell Experimenters Guide. Indianapolis,
Ind.: H. W. Sams, 1965.
Perlin, John. From Space to Earth: The Story of Solar Electricity. Ann Arbor,
Mich.: Aatec Publications, 1999.
Walker, R. C., and T. M. C. Lance. Photoelectric Cell Applications: A
Practical Book Describing the Uses of Photoelectric Cells in Television,
Talking Pictures, Electrical Alarms, Counting Devices, Etc. 3ded.
London: Sir I. Pitman & Sons, 1938.

Photovoltaic cell
Photovoltaic cell
The invention: Drawing their energy directly from the Sun, the
first photovoltaic cells powered instruments on early space vehicles
and held out hope for future uses of solar energy.
The people behind the invention:
Daryl M. Chapin (1906-1995), an American physicist
Calvin S. Fuller (1902-1994), an American chemist
Gerald L. Pearson (1905- ), an American physicist
Unlimited Energy Source
All the energy that the world has at its disposal ultimately comes
from the Sun. Some of this solar energy was trapped millions of years
ago in the form of vegetable and animal matter that became the coal,
oil, and natural gas that the world relies upon for energy. Some of this
fuel is used directly to heat homes and to power factories and gasoline
vehicles. Much of this fossil fuel, however, is burned to produce
the electricity on which modern society depends.
The amount of energy available from the Sun is difficult to imagine,
but some comparisons may be helpful. During each forty-hour
period, the Sun provides the earth with as much energy as the
earth’s total reserves of coal, oil, and natural gas. It has been estimated
that the amount of energy provided by the sun’s radiation
matches the earth’s reserves of nuclear fuel every forty days. The
annual solar radiation that falls on about twelve hundred square
miles of land in Arizona matched the world’s estimated total annual
energy requirement for 1960. Scientists have been searching for
many decades for inexpensive, efficient means of converting this
vast supply of solar radiation directly into electricity.
The Bell Solar Cell
567
Throughout its history, Bell Systems has needed to be able to
transmit, modulate, and amplify electrical signals. Until the 1930’s,
these tasks were accomplished by using insulators and metallic con-

568 / Photovoltaic cell
ductors. At that time, semiconductors, which have electrical properties
that are between those of insulators and those of conductors,
were developed. One of the most important semiconductor materials
is silicon, which is one of the most common elements on the
earth. Unfortunately, silicon is usually found in the form of compounds
such as sand or quartz, and it must be refined and purified
before it can be used in electrical circuits. This process required
much initial research, and very pure silicon was not available until
the early 1950’s.
Electric conduction in silicon is the result of the movement of
negative charges (electrons) or positive charges (holes). One way of
accomplishing this is by deliberately adding to the silicon phosphorus
or arsenic atoms, which have five outer electrons. This addition
creates a type of semiconductor that has excess negative charges (an
n-type semiconductor). Adding boron atoms, which have three
outer electrons, creates a semiconductor that has excess positive
charges (a p-type semiconductor). Calvin Fuller made an important
study of the formation of p-n junctions, which are the points at
which p-type and n-type semiconductors meet, by using the process
of diffusing impurity atoms—that is, adding atoms of materials that
would increase the level of positive or negative charges, as described
above. Fuller’s work stimulated interested in using the process
of impurity diffusion to create cells that would turn solar energy
into electricity. Fuller and Gerald Pearson made the first largearea
p-n junction by using the diffusion process. Daryl Chapin,
Fuller, and Pearson made a similar p-n junction very close to the
surface of a silicon crystal, which was then exposed to sunlight.
The cell was constructed by first making an ingot of arsenicdoped
silicon that was then cut into very thin slices. Then a very
thin layer of p-type silicon was formed over the surface of the n-type
wafer, providing a p-n junction close to the surface of the cell. Once
the cell cooled, the p-type layer was removed from the back of the
cell and lead wires were attached to the two surfaces. When light
was absorbed at the p-n junction, electron-hole pairs were produced,
and the electric field that was present at the junction forced
the electrons to the n side and the holes to the p side.
The recombination of the electrons and holes takes place after the
electrons have traveled through the external wires, where they do

useful work. Chapin, Fuller, and Pearson announced in 1954 that
the resulting photovoltaic cell was the most efficient (6 percent)
means then available for converting sunlight into electricity.
The first experimental use of the silicon solar battery was in amplifiers
for electrical telephone signals in rural areas. An array of 432
silicon cells, capable of supplying 9 watts of power in bright sunlight,
was used to charge a nickel-cadmium storage battery. This, in
turn, powered the amplifier for the telephone signal. The electrical
energy derived from sunlight during the day was sufficient to keep
the storage battery charged for continuous operation. The system
was successfully tested for six months of continuous use in Americus,
Georgia, in 1956. Although it was a technical success, the silicon solar
cell was not ready to compete economically with conventional
means of producing electrical power.
Consequences
Parabolic mirrors at a solar power plant. (PhotoDisc)
Photovoltaic cell / 569
One of the immediate applications of the solar cell was to supply
electrical energy for Telstar satellites. These cells are used extensively
on all satellites to generate power. The success of the U.S. sat-

570 / Photovoltaic cell
ellite program prompted serious suggestions in 1965 for the use of
an orbiting power satellite. A large satellite could be placed into a
synchronous orbit of the earth. It would collect sunlight, convert it
to microwave radiation, and beam the energy to an Earth-based receiving
station. Many technical problems must be solved, however,
before this dream can become a reality.
Solar cells are used in small-scale applications such as power
sources for calculators. Large-scale applications are still not economically
competitive with more traditional means of generating
electric power. The development of the Third World countries, however,
may provide the incentive to search for less-expensive solar
cells that can be used, for example, to provide energy in remote villages.
As the standards of living in such areas improve, the need for
electric power will grow. Solar cells may be able to provide the necessary
energy while safeguarding the environment for future generations.
See also Alkaline storage battery; Fluorescent lighting; Fuel cell;
Photoelectric cell; Solar thermal engine.
Further Reading
Green, Martin A. Power to the People: Sunlight to Electricity Using Solar
Cells. Sydney, Australia: University of South Wales Press, 2000.
_____. “Photovoltaics: Technology Overview.” Energy Policy 28, no.
14 (November, 2000).
Perlin, John. From Space to Earth: The Story of Solar Electricity. Ann Arbor,
Mich.: Aatec Publications, 1999.

Plastic
Plastic
The invention: The first totally synthetic thermosetting plastic,
which paved the way for modern materials science.
The people behind the invention:
John Wesley Hyatt (1837-1920), an American inventor
Leo Hendrik Baekeland (1863-1944), a Belgian-born chemist,
consultant, and inventor
Christian Friedrich Schönbein (1799-1868), a German chemist
who produced guncotton, the first artificial polymer
Adolf von Baeyer (1835-1917), a German chemist
Exploding Billiard Balls
571
In the 1860’s, the firm of Phelan and Collender offered a prize of
ten thousand dollars to anyone producing a substance that could
serve as an inexpensive substitute for ivory, which was somewhat
difficult to obtain in large quantities at reasonable prices. Earlier,
Christian Friedrich Schönbein had laid the groundwork for a breakthrough
in the quest for a new material in 1846 by the serendipitous
discovery of nitrocellulose, more commonly known as “guncotton,”
which was produced by the reaction of nitric acid with cotton.
An American inventor, John Wesley Hyatt, while looking for a
substitute for ivory as a material for making billiard balls, discovered
that the addition of camphor to nitrocellulose under certain
conditions led to the formation of a white material that could be
molded and machined. He dubbed this substance “celluloid,” and
this product is now acknowledged as the first synthetic plastic. Celluloid
won the prize for Hyatt, and he promptly set out to exploit his
product. Celluloid was used to make baby rattles, collars, dentures,
and other manufactured goods.
As a billiard ball substitute, however, it was not really adequate,
for various reasons. First, it is thermoplastic—in other words, a material
that softens when heated and can then be easily deformed or
molded. It was thus too soft for billiard ball use. Second, it was
highly flammable, hardly a desirable characteristic. A widely circu-

572 / Plastic
lated, perhaps apocryphal, story claimed that celluloid billiard balls
detonated when they collided.
Truly Artificial
Since celluloid can be viewed as a derivative of a natural product,
it is not a completely synthetic substance. Leo Hendrik Baekeland
has the distinction of being the first to produce a completely artificial
plastic. Born in Ghent, Belgium, Baekeland emigrated to the
United States in 1889 to pursue applied research, a pursuit not encouraged
in Europe at the time. One area in which Baekeland hoped
to make an inroad was in the development of an artificial shellac.
Shellac at the time was a natural and therefore expensive product,
and there would be a wide market for any reasonably priced substitute.
Baekeland’s research scheme, begun in 1905, focused on finding
a solvent that could dissolve the resinous products from a certain
class of organic chemical reaction.
The particular resins he used had been reported in the mid-
1800’s by the German chemist Adolf von Baeyer. These resins were
produced by the condensation reaction of formaldehyde with a
class of chemicals called “phenols.” Baeyer found that frequently
the major product of such a reaction was a gummy residue that was
virtually impossible to remove from glassware. Baekeland focused
on finding a material that could dissolve these resinous products.
Such a substance would prove to be the shellac substitute he sought.
These efforts proved frustrating, as an adequate solvent for these
resins could not be found. After repeated attempts to dissolve these
residues, Baekeland shifted the orientation of his work. Abandoning
the quest to dissolve the resin, he set about trying to develop a resin
that would be impervious to any solvent, reasoning that such a material
would have useful applications.
Baekeland’s experiments involved the manipulation of phenolformaldehyde
reactions through precise control of the temperature
and pressure at which the reactions were performed. Many of these
experiments were performed in a 1.5-meter-tall reactor vessel, which
he called a “Bakelizer.” In 1907, these meticulous experiments paid
off when Baekeland opened the reactor to reveal a clear solid that
was heat resistant, nonconducting, and machinable. Experimenta-

Plastic / 573
tion proved that the material could be dyed practically any color in
the manufacturing process, with no effect on the physical properties
of the solid.
Baekeland filed a patent for this new material in 1907. (This patent
was filed one day before that filed by James Swinburne, a British
John Wesley Hyatt
John Wesley Hyatt’s parents wanted him to be a minister, a
step up in status from his father’s job as a blacksmith. Born in
1837 in Starkey, New York, Hyatt received the standard primary
education and then obediently went to a seminary as a teenager.
However, his mind was on making things rather than spirituality;
he was especially ingenious with machinery. The seminary
held him only a year. He became a printer’s apprentice at
sixteen and later set up shop in Albany.
His mind ranged beyond printing too. He invented a method
to make emery wheels for sharpening cutlery, which brought
him his first patent at twenty-four. In an attempt to win the
Phelan and Collender Company contest for artificial billiard
balls, he developed several moldable compounds from wood
pulp. He started the Embossing Company in Albany to make
chess and checker pieces from the compounds and put his
youngest brother in charge. With another brother he experimented
with guncotton until he invented celluloid. In 1872, he
and his brothers started the Celluloid Manufacturing Company.
They designed new milling machinery for the new substance
and turned out billiard balls, bowling balls, golf club
heads and other sporting goods but then branched out into domestic
items, such as boxes, handles, combs, and even collars.
Celluloid became the basic material of photographic film and,
later, motion picture film.
Meanwhile, Hyatt continued to invent—machinery for cutting
and molding plastic and rolling steel, a water purification
system, a method for squeezing juice from sugar cane, an industrial
sewing machine, roller bearings for heavy machinery—registering
more than 250 patents, which is impressive for
a person with no formal scientific or technical training. The Society
of Chemical Industry awarded Hyatt its prestigious Perkin
Medal in 1914. Hyatt died in 1920.

574 / Plastic
electrical engineer who had developed a similar material in his
quest to produce an insulating material.) Baekeland dubbed his new
creation “Bakelite” and announced its existence to the scientific
community on February 15, 1909, at the annual meeting of the American
Chemical Society. Among its first uses was in the manufacture
of ignition parts for the rapidly growing automobile industry.
Impact
Bakelite proved to be the first of a class of compounds called
“synthetic polymers.” Polymers are long chains of molecules chemically
linked together. There are many natural polymers, such as cotton.
The discovery of synthetic polymers led to vigorous research
into the field and attempts to produce other useful artificial materials.
These efforts met with a fair amount of success; by 1940, a multitude
of new products unlike anything found in nature had been discovered.
These included such items as polystyrene and low-density
polyethylene. In addition, artificial substitutes for natural polymers,
such as rubber, were a goal of polymer chemists. One of the results
of this research was the development of neoprene.
Industries also were interested in developing synthetic polymers
to produce materials that could be used in place of natural fibers
such as cotton. The most dramatic success in this area was achieved
by Du Pont chemist Wallace Carothers, who had also developed
neoprene. Carothers focused his energies on forming a synthetic fiber
similar to silk, resulting in the synthesis of nylon.
Synthetic polymers constitute one branch of a broad area known
as “materials science.” Novel, useful materials produced synthetically
from a variety of natural materials have allowed for tremendous
progress in many areas. Examples of these new materials include
high-temperature superconductors, composites, ceramics, and
plastics. These materials are used to make the structural components
of aircraft, artificial limbs and implants, tennis rackets, garbage
bags, and many other common objects.
See also Buna rubber; Contact lenses; Laminated glass; Neoprene;
Nylon; Orlon; Polyester; Polyethylene; Polystyrene; Pyrex
glass; Silicones; Teflon; Velcro.

Further Reading
Plastic / 575
Amato, Ivan. “Chemist: Leo Baekeland.” Time 153, no. 12 (March 29,
1999).
Clark, Tessa. Bakelite Style. Edison, N.J.: Chartwell Books, 1997.
Fenichell, Stephen. Plastic: The Making of a Synthetic Century. New
York: HarperBusiness, 1997.
Sparke, Penny. The Plastics Age: From Bakelite to Beanbags and Beyond.
Woodstock, N.Y.: Overlook Press, 1990.

576
Pocket calculator
Pocket calculator
The invention: The first portable and reliable hand-held calculator
capable of performing a wide range of mathematical computations.
The people behind the invention:
Jack St. Clair Kilby (1923- ), the inventor of the
semiconductor microchip
Jerry D. Merryman (1932- ), the first project manager of the
team that invented the first portable calculator
James Van Tassel (1929- ), an inventor and expert on
semiconductor components
An Ancient Dream
In the earliest accounts of civilizations that developed number
systems to perform mathematical calculations, evidence has been
found of efforts to fashion a device that would permit people to perform
these calculations with reduced effort and increased accuracy.
The ancient Babylonians are regarded as the inventors of the first
abacus (or counting board, from the Greek abakos, meaning “board”
or “tablet”). It was originally little more than a row of shallow
grooves with pebbles or bone fragments as counters.
The next step in mechanical calculation did not occur until the
early seventeenth century. John Napier, a Scottish baron and mathematician,
originated the concept of “logarithms” as a mathematical
device to make calculating easier. This concept led to the first slide
rule, created by the English mathematician William Oughtred of
Cambridge. Oughtred’s invention consisted of two identical, circular
logarithmic scales held together and adjusted by hand. The slide
rule made it possible to perform rough but rapid multiplication and
division. Oughtred’s invention in 1623 was paralleled by the work
of a German professor, Wilhelm Schickard, who built a “calculating
clock” the same year. Because the record of Schickard’s work was
lost until 1935, however, the French mathematician Blaise Pascal
was generally thought to have built the first mechanical calculator,
the “Pascaline,” in 1645.

Other versions of mechanical calculators were built in later centuries,
but none was rapid or compact enough to be useful beyond specific
laboratory or mercantile situations. Meanwhile, the dream of
such a machine continued to fascinate scientists and mathematicians.
The development that made a fast, small calculator possible did
not occur until the middle of the twentieth century, when Jack St.
Clair Kilby of Texas Instruments invented the silicon microchip (or
integrated circuit) in 1958. An integrated circuit is a tiny complex of
electronic components and their connections that is produced in or
on a small slice of semiconductor material such as silicon. Patrick
Haggerty, then president of Texas Instruments, wrote in 1964 that
“integrated electronics” would “remove limitations” that determined
the size of instruments, and he recognized that Kilby’s invention
of the microchip made possible the creation of a portable,
hand-held calculator. He challenged Kilby to put together a team to
design a calculator that would be as powerful as the large, electromechanical
models in use at the time but small enough to fit into a
coat pocket. Working with Jerry D. Merryman and James Van Tassel,
Kilby began to work on the project in October, 1965.
An Amazing Reality
Pocket calculator / 577
At the outset, there were basically five elements that had to be designed.
These were the logic designs that enabled the machine to
perform the actual calculations, the keyboard or keypad, the power
supply, the readout display, and the outer case. Kilby recalls that
once a particular size for the unit had been determined (something
that could be easily held in the hand), project manager Merryman
was able to develop the initial logic designs in three days. Van Tassel
contributed his experience with semiconductor components to solve
the problems of packaging the integrated circuit. The display required
a thermal printer that would work on a low power source.
The machine also had to include a microencapsulated ink source so
that the paper readouts could be imprinted clearly. Then the paper
had to be advanced for the next calculation. Kilby, Merryman, and
Van Tassel filed for a patent on their work in 1967.
Although this relatively small, working prototype of the minicalculator
made obsolete the transistor-operated design of the much

578 / Pocket calculator
Jerry D. Merryman
In 1965 Texas Instruments assigned two engineers to join
Jack St. Clair Kilby, inventor of the integrated circuit, in an effort
to produce a pocket-sized calculator: James H. Van Tassel, a
specialist in semiconductor components, and Jerry D. Merryman,
a versatile engineer who became the project manager. It
took Merryman only seventy-two hours to work out the logic
design for the calculator, and the team set about designing, fabricating,
and testing its components. After two years, it had a
prototype, the first pocket calculator. However, it required a
large, strong pocket. It measured 4.25 inches by 6.12 inches by
1.76 inches and weighed 2.8 pounds. Kilby, Van Tassel, and
Merry filed for a patent and received it in 1975. In 1989 the team
was jointly presented the Holley Medical for the achievement
by the American Society of Mechanical Engineers. By then
Merryman held sixty other patents, foreign and domestic.
Born in 1932, Merryman grew up in Hearne, Texas, and after
high school went to Texas A&M University. He never graduated,
but he did become extraordinarily adept at electrical engineering,
teaching himself what he needed to know while doing
small jobs on his own. He was said to have almost an intuitive
sense for circuitry. After he joined Texas Instruments in 1963
he quickly earned a reputation for solving complex problems,
one of the reasons he was made part of the hand calculator
team. He became a Texas Instruments Fellow in 1975 and helped
design semiconductor manufacturing equipment, particularly
by adapting high-speed lasers for use in extremely fine optical
lithography. He also invented thermal data systems.
Along with Kilby and Van Tassel, Merryman received the
George R. Stibitz Computer Pioneer Award in 1997.
larger desk calculators, the cost of setting up new production lines
and the need to develop a market made it impractical to begin production
immediately. Instead, Texas Instruments and Canon of Tokyo
formed a joint venture, which led to the introduction of the
Canon Pocketronic Printing Calculator in Japan in April, 1970, and
in the United States that fall. Built entirely of Texas Instruments
parts, this four-function machine with three metal oxide semicon-

Pocket calculator / 579
True pocket calculators fit as easily in shirt pockets as pencils and pens. (PhotoDisc)
ductor (MOS) circuits was similar to the prototype designed in 1967.
The calculator was priced at $400, weighed 740 grams, and measured
101 millimeters wide by 208 millimeters long by 49 millimeters
high. It could perform twelve-digit calculations and worked up
to four decimal places.
In September, 1972, Texas Instruments put the Datamath, its first
commercial hand-held calculator using a single MOS chip, on the
retail market. It weighed 340 grams and measured 75 millimeters
wide by 137 millimeters long by 42 millimeters high. The Datamath
was priced at $120 and included a full-floating decimal point that
could appear anywhere among the numbers on its eight-digit, lightemitting
diode (LED) display. It came with a rechargeable battery
that could also be connected to a standard alternating current (AC)
outlet. The Datamath also had the ability to conserve power while
awaiting the next keyboard entry. Finally, the machine had a built-in
limited amount of memory storage.

580 / Pocket calculator
Consequences
Prior to 1970, most calculating machines were of such dimensions
that professional mathematicians and engineers were either tied to
their desks or else carried slide rules whenever they had to be away
from their offices. By 1975, Keuffel & Esser, the largest slide rule manufacturer
in the world, was producing its last model, and mechanical
engineers found that problems that had previously taken a week
could now be solved in an hour using the new machines.
That year, the Smithsonian Institution accepted the world’s first
miniature electronic calculator for its permanent collection, noting
that it was the forerunner of more than one hundred million pocket
calculators then in use. By the 1990’s, more than fifty million portable
units were being sold each year in the United States. In general,
the electronic pocket calculator revolutionized the way in which
people related to the world of numbers.
Moreover, the portability of the hand-held calculator made it
ideal for use in remote locations, such as those a petroleum engineer
might have to explore. Its rapidity and reliability made it an indispensable
instrument for construction engineers, architects, and real
estate agents, who could figure the volume of a room and other
building dimensions almost instantly and then produce cost estimates
almost on the spot.
See also Cell phone; Differential analyzer; Mark I calculator; Personal
computer; Transistor radio; Walkman cassette player.
Further Reading
Ball, Guy. Collector’s Guide to Pocket Calculators. Tustin, Calif.: Wilson/Barnett
Publishing, 1996.
Clayton, Mark. “Calculators in Class: Freedom from Scratch Paper
or ‘Crutch’?” Christian Science Monitor (May 23, 2000).
Lederer, Victor. “Calculators: The Applications Are Unlimited. Administrative
Management 38 (July, 1977).
Lee, Jennifer. “Throw Teachers a New Curve.” New York Times (September
2, 1999).
“The Semiconductor Becomes a New Marketing Force.” Business
Week (August 24, 1974).

Polio vaccine (Sabin)
Polio vaccine (Sabin)
The invention: Albert Bruce Sabin’s vaccine was the first to stimulate
long-lasting immunity against polio without the risk of causing
paralytic disease.
The people behind the invention:
Albert Bruce Sabin (1906-1993), a Russian-born American
virologist
Jonas Edward Salk (1914-1995), an American physician,
immunologist, and virologist
Renato Dulbecco (1914- ), an Italian-born American
virologist who shared the 1975 Nobel Prize in Physiology or
Medicine
The Search for a Living Vaccine
581
Almost a century ago, the first major poliomyelitis (polio) epidemic
was recorded. Thereafter, epidemics of increasing frequency
and severity struck the industrialized world. By the 1950’s, as many
as sixteen thousand individuals, most of them children, were being
paralyzed by the disease each year.
Poliovirus enters the body through ingestion by the mouth. It
replicates in the throat and the intestines and establishes an infection
that normally is harmless. From there, the virus can enter the
bloodstream. In some individuals it makes its way to the nervous
system, where it attacks and destroys nerve cells crucial for muscle
movement. The presence of antibodies in the bloodstream will prevent
the virus from reaching the nervous system and causing paralysis.
Thus, the goal of vaccination is to administer poliovirus that
has been altered so that it cannot cause disease but nevertheless will
stimulate the production of antibodies to fight the disease.
Albert Bruce Sabin received his medical degree from New York
University College of Medicine in 1931. Polio was epidemic in 1931,
and for Sabin polio research became a lifelong interest. In 1936,
while working at the Rockefeller Institute, Sabin and Peter Olinsky
successfully grew poliovirus using tissues cultured in vitro. Tissue
culture proved to be an excellent source of virus. Jonas Edward Salk

582 / Polio vaccine (Sabin)
soon developed an inactive polio vaccine consisting of virus grown
from tissue culture that had been inactivated (killed) by chemical
treatment. This vaccine became available for general use in 1955, almost
fifty years after poliovirus had first been identified.
Sabin, however, was not convinced that an inactivated virus vaccine
was adequate. He believed that it would provide only temporary
protection and that individuals would have to be vaccinated
repeatedly in order to maintain protective levels of antibodies.
Knowing that natural infection with poliovirus induced lifelong immunity,
Sabin believed that a vaccine consisting of a living virus
was necessary to produce long-lasting immunity. Also, unlike the
inactive vaccine, which is injected, a living virus (weakened so that
it would not cause disease) could be taken orally and would invade
the body and replicate of its own accord.
Sabin was not alone in his beliefs. Hilary Koprowski and Harold
Cox also favored a living virus vaccine and had, in fact, begun
searching for weakened strains of poliovirus as early as 1946 by repeatedly
growing the virus in rodents. When Sabin began his search
for weakened virus strains in 1953, a fiercely competitive contest ensued
to achieve an acceptable live virus vaccine.
Rare, Mutant Polioviruses
Sabin’s approach was based on the principle that, as viruses acquire
the ability to replicate in a foreign species or tissue (for example,
in mice), they become less able to replicate in humans and thus
less able to cause disease. Sabin used tissue culture techniques to
isolate those polioviruses that grew most rapidly in monkey kidney
cells. He then employed a technique developed by Renato Dulbecco
that allowed him to recover individual virus particles. The recovered
viruses were injected directly into the brains or spinal cords of
monkeys in order to identify those viruses that did not damage the
nervous system. These meticulously performed experiments, which
involved approximately nine thousand monkeys and more than
one hundred chimpanzees, finally enabled Sabin to isolate rare mutant
polioviruses that would replicate in the intestinal tract but not
in the nervous systems of chimpanzees or, it was hoped, of humans.
In addition, the weakened virus strains were shown to stimulate an-

Polio vaccine (Sabin) / 583
tibodies when they were fed to chimpanzees; this was a critical attribute
for a vaccine strain.
By 1957, Sabin had identified three strains of attenuated viruses that
were ready for small experimental trials in humans. A small group of
volunteers, including Sabin’s own wife and children, were fed the vaccine
with promising results. Sabin then gave his vaccine to virologists
in the Soviet Union, Eastern Europe, Mexico, and Holland for further
testing. Combined with smaller studies in the United States, these trials
established the effectiveness and safety of his oral vaccine.
During this period, the strains developed by Cox and by Koprowski
were being tested also in millions of persons in field trials
around the world. In 1958, two laboratories independently compared
the vaccine strains and concluded that the Sabin strains were
superior. In 1962, after four years of deliberation by the U.S. Public
Health Service, all three of Sabin’s vaccine strains were licensed for
general use.
Albert Sabin
Born in Bialystok, Poland, in 1906, Albert Bruce Sabin emigrated
with his family to the United States in 1921. Like Jonas
Salk—the other great inventor of a polio vaccine—Sabin earned
his medical degree at New York University (1931), where he began
his research on polio.
While in the U.S. Army Medical Corps during World War II,
he helped produce vaccines for dengue fever and Japanese encephalitis.
After the war he returned to his professorship at the
University of Cincinnati College of Medicine and Children’s
Hospital Research Foundation. The polio vaccine he developed
there saved millions of children worldwide from paralytic polio.
Many of these lives were doubtless saved because of his refusal
to patent the vaccine, thereby making it simpler to produce
and distribute and less expensive to administer
Sabin’s work brought him more than forty honorary degrees
from American and foreign universities and medals from the
governments of the United States and Soviet Union. He was
president of the Weizmann Institute of Science after 1970 and
later became a professor of biomedicine at the Medical University
of South Carolina. He died in 1993.

584 / Polio vaccine (Sabin)
Consequences
The development of polio vaccines ranks as one of the triumphs of
modern medicine. In the early 1950’s, paralytic polio struck 13,500
out of every 100 million Americans. The use of the Salk vaccine
greatly reduced the incidence of polio, but outbreaks of paralytic disease
continued to occur: Fifty-seven hundred cases were reported in
1959 and twenty-five hundred cases in 1960. In 1962, the oral Sabin
vaccine became the vaccine of choice in the United States. Since its
widespread use, the number of paralytic cases in the United States
has dropped precipitously, eventually averaging fewer than ten per
year. Worldwide, the oral vaccine prevented an estimated 5 million
cases of paralytic poliomyelitis between 1970 and 1990.
The oral vaccine is not without problems. Occasionally, the living
virus mutates to a disease-causing (virulent) form as it multiplies in
the vaccinated person. When this occurs, the person may develop
paralytic poliomyelitis. The inactive vaccine, in contrast, cannot
mutate to a virulent form. Ironically, nearly every incidence of polio
in the United States is caused by the vaccine itself.
In the developing countries of the world, the issue of vaccination is
more pressing. Millions receive neither form of polio vaccine; as a result,
at least 250,000 individuals are paralyzed or die each year. The World
Health Organization and other health providers continue to work toward
the very practical goal of completely eradicating this disease.
See also Antibacterial drugs; Birth control pill; Iron lung; Penicillin;
Polio vaccine (Salk); Reserpine; Salvarsan; Tuberculosis vaccine;
Typhus vaccine; Yellow fever vaccine.
Further Reading
DeJauregui, Ruth. 100 Medical Milestones That Shaped World History.
San Mateo, Calif.: Bluewood Books, 1998.
Grady, Denise. “As Polio Fades, Dr. Salk’s Vaccine Re-emerges.”
New York Times (December 14, 1999).
Plotkin, Stanley A., and Edward A. Mortimer. Vaccines. 2d ed. Philadelphia:
W. B. Saunders, 1994.
Seavey, Nina Gilden, Jane S. Smith, and Paul Wagner. A Paralyzing
Fear: The Triumph over Polio in America. New York: TV Books, 1998.

Polio vaccine (Salk)
Polio vaccine (Salk)
The invention: Jonas Salk’s vaccine was the first that prevented polio,
resulting in the virtual eradication of crippling polio epidemics.
The people behind the invention:
Jonas Edward Salk (1914-1995), an American physician,
immunologist, and virologist
Thomas Francis, Jr. (1900-1969), an American microbiologist
Cause for Celebration
585
Poliomyelitis (polio) is an infectious disease that can adversely
affect the central nervous system, causing paralysis and great muscle
wasting due to the destruction of motor neurons (nerve cells) in
the spinal cord. Epidemiologists believe that polio has existed since
ancient times, and evidence of its presence in Egypt, circa 1400 b.c.e.,
has been presented. Fortunately, the Salk vaccine and the later vaccine
developed by the American virologist Albert Bruce Sabin can
prevent the disease. Consequently, except in underdeveloped nations,
polio is rare. Moreover, although once a person develops polio,
there is still no cure for it, a large number of polio cases end without
paralysis or any observable effect.
Polio is often called “infantile paralysis.” This results from the
fact that it is seen most often in children. It is caused by a virus and
begins with body aches, a stiff neck, and other symptoms that are
very similar to those of a severe case of influenza. In some cases,
within two weeks after its onset, the course of polio begins to lead to
muscle wasting and paralysis.
On April 12, 1955, the world was thrilled with the announcement
that Jonas Edward Salk’s poliomyelitis vaccine could prevent the
disease. It was reported that schools were closed in celebration of
this event. Salk, the son of a New York City garment worker, has
since become one of the most well-known and publicly venerated
medical scientists in the world.
Vaccination is a method of disease prevention by immunization,
whereby a small amount of virus is injected into the body to prevent

586 / Polio vaccine (Salk)
a viral disease. The process depends on the production of antibodies
(body proteins that are specifically coded to prevent the disease
spread by the virus) in response to the vaccination. Vaccines are
made of weakened or killed virus preparations.
Electrifying Results
Jonas Salk
The son of a garment industry worker, Jonas Edward Salk
was born in New York City in 1914. He worked his way through
school, graduating from New York University School of Medicine
in 1938. Afterward he joined microbiologist Thomas Francis,
Jr., in developing a vaccine for influenza.
In 1942, Salk began a research fellowship at the University of
Michigan and subsequently joined the epidemiology faculty.
He moved to the University of Pittsburgh in 1947, directing its
Viral Research Lab, and while there developed his vaccine for
poliomyelitis. The discovery catapulted Salk into worldwide
fame, but he was a controversial figure among scientists.
Although Salk received the Presidential Medal of Freedom,
a Congressional gold medal, and the Nehru Award for International
Understanding, he was turned down for membership in
the National Academy of Sciences. In 1963 he opened the Salk
Institute for Biological Sciences in La Jolla, California. Well
aware of his reputation among medical researchers, he once
joked, “I couldn’t possibly have become a member of this institute
if I hadn’t founded it myself.” He died in 1995.
The Salk vaccine was produced in two steps. First, polio viruses
were grown in monkey kidney tissue cultures. These polio viruses
were then killed by treatment with the right amount of formaldehyde
to produce an effective vaccine. The killed-virus polio vaccine
was found to be safe and to cause the production of antibodies
against the disease, a sign that it should prevent polio.
In early 1952, Salk tested a prototype vaccine against Type I polio virus
on children who were afflicted with the disease and were thus
deemed safe from reinfection. This test showed that the vaccination

greatly elevated the concentration of polio antibodies in these children.
On July 2, 1952, encouraged by these results, Salk vaccinated fortythree
children who had never had polio with vaccines against each of
the three virus types (Type I, Type II, and Type III). All inoculated children
produced high levels of polio antibodies, and none of them developed
the disease. Consequently, the vaccine appeared to be both safe in
humans and likely to become an effective public health tool.
In 1953, Salk reported these findings in the Journal of the American
Medical Association. In April, 1954, nationwide testing of the Salk
vaccine began, via the mass vaccination of American schoolchildren.
The results of the trial were electrifying. The vaccine was safe,
and it greatly reduced the incidence of the disease. In fact, it was estimated
that Salk’s vaccine gave schoolchildren 60 to 90 percent protection
against polio.
Salk was instantly praised. Then, however, several cases of polio
occurred as a consequence of the vaccine. Its use was immediately
suspended by the U.S. surgeon general, pending a complete examination.
Soon, it was evident that all the cases of vaccine-derived polio
were attributable to faulty batches of vaccine made by one
pharmaceutical company. Salk and his associates were in no way responsible
for the problem. Appropriate steps were taken to ensure
that such an error would not be repeated, and the Salk vaccine was
again released for use by the public.
Consequences
Polio vaccine (Salk) / 587
The first reports on the polio epidemic in the United States had
occurred on June 27, 1916, when one hundred residents of Brooklyn,
New York, were afflicted. Soon, the disease had spread. By August,
twenty-seven thousand people had developed polio. Nearly seven
thousand afflicted people died, and many survivors of the epidemic
were permanently paralyzed to varying extents. In New York City
alone, nine thousand people developed polio and two thousand
died. Chaos reigned as large numbers of terrified people attempted
to leave and were turned back by police. Smaller polio epidemics
occurred throughout the nation in the years that followed (for example,
the Catawba County, North Carolina, epidemic of 1944). A
particularly horrible aspect of polio was the fact that more than 70

588 / Polio vaccine (Salk)
percent of polio victims were small children. Adults caught it too;
the most famous of these adult polio victims was U.S. President
Franklin D. Roosevelt. There was no cure for the disease. The best
available treatment was physical therapy.
As of August, 1955, more than four million polio vaccines had
been given. The Salk vaccine appeared to work very well. There were
only half as many reported cases of polio in 1956 as there had been in
1955. It appeared that polio was being conquered. By 1957, the number
of cases reported nationwide had fallen below six thousand.
Thus, in two years, its incidence had dropped by about 80 percent.
This was very exciting, and soon other countries clamored for the
vaccine. By 1959, ninety other countries had been supplied with the
Salk vaccine. Worldwide, the disease was being eradicated. The introduction
of an oral polio vaccine by Albert Bruce Sabin supported
this progress.
Salk received many honors, including honorary degrees from
American and foreign universities, the Lasker Award, a Congressional
Medal for Distinguished Civilian Service, and membership in
the French Legion of Honor, yet he received neither the Nobel Prize
nor membership in the American National Academy of Sciences. It
is believed by many that this neglect was a result of the personal antagonism
of some of the members of the scientific community who
strongly disagreed with his theories of viral inactivation.
See also Antibacterial drugs; Birth control pill; Iron lung; Penicillin;
Polio vaccine (Sabin); Reserpine; Salvarsan; Tuberculosis vaccine;
Typhus vaccine; Yellow fever vaccine.
Further Reading
DeJauregui, Ruth. 100 Medical Milestones That Shaped World History.
San Mateo, Calif.: Bluewood Books, 1998.
Plotkin, Stanley A., and Edward A. Mortimer. Vaccines. 2d ed. Philadelphia:
W. B. Saunders, 1994.
Seavey, Nina Gilden, Jane S. Smith, and Paul Wagner. A Paralyzing
Fear: The Triumph over Polio in America. New York: TV Books, 1998.
Smith, Jane S. Patenting the Sun: Polio and the Salk Vaccine. New York:
Anchor/Doubleday, 1991.

Polyester
Polyester
The invention: A synthetic fibrous polymer used especially in fabrics.
The people behind the invention:
Wallace H. Carothers (1896-1937), an American polymer
chemist
Hilaire de Chardonnet (1839-1924), a French polymer chemist
John R. Whinfield (1901-1966), a British polymer chemist
A Story About Threads
589
Human beings have worn clothing since prehistoric times. At
first, clothing consisted of animal skins sewed together. Later, people
learned to spin threads from the fibers in plant or animal materials
and to weave fabrics from the threads (for example, wool, silk,
and cotton). By the end of the nineteenth century, efforts were begun
to produce synthetic fibers for use in fabrics. These efforts were
motivated by two concerns. First, it seemed likely that natural materials
would become too scarce to meet the needs of a rapidly increasing
world population. Second, a series of natural disasters—
affecting the silk industry in particular—had demonstrated the
problems of relying solely on natural fibers for fabrics.
The first efforts to develop synthetic fabric focused on artificial
silk, because of the high cost of silk, its beauty, and the fact that silk
production had been interrupted by natural disasters more often
than the production of any other material. The first synthetic silk
was rayon, which was originally patented by a French count,
Hilaire de Chardonnet, and was later much improved by other
polymer chemists. Rayon is a semisynthetic material that is made
from wood pulp or cotton.
Because there was a need for synthetic fabrics whose manufacture
did not require natural materials, other avenues were explored. One
of these avenues led to the development of totally synthetic polyester
fibers. In the United States, the best-known of these is Dacron, which
is manufactured by E. I. Du Pont de Nemours. Easily made into

590 / Polyester
threads, Dacron is widely used in clothing. It is also used to make audiotapes
and videotapes and in automobile and boat bodies.
From Polymers to Polyester
Dacron belongs to a group of chemicals known as “synthetic
polymers.” All polymers are made of giant molecules, each of
which is composed of a large number of simpler molecules (“monomers”)
that have been linked, chemically, to form long strings. Efforts
by industrial chemists to prepare synthetic polymers developed
in the twentieth century after it was discovered that many
natural building materials and fabrics (such as rubber, wood, wool,
silk, and cotton) were polymers, and as the ways in which monomers
could be joined to make polymers became better understood.
One group of chemists who studied polymers sought to make inexpensive
synthetic fibers to replace expensive silk and wool. Their efforts
led to the development of well-known synthetic fibers such as
nylon and Dacron.
Wallace H. Carothers of Du Pont pioneered the development of
polyamide polymers, collectively called “nylon,” and was the first
researcher to attempt to make polyester. It was British polymer
chemists John R. Whinfield and J. T. Dickson of Calico Printers Association
(CPA) Limited, however, who in 1941 perfected and patented
polyester that could be used to manufacture clothing. The
first polyester fiber products were produced in 1950 in Great Britain
by London’s British Imperial Chemical Industries, which had secured
the British patent rights from CPA. This polyester, which was
made of two monomers, terphthalic acid and ethylene glycol, was
called Terylene. In 1951, Du Pont, which had acquired Terylene patent
rights for the Western Hemisphere, began to market its own version
of this polyester, which was called Dacron. Soon, other companies
around the world were selling polyester materials of similar
composition.
Dacron and other polyesters are used in many items in the
United States. Made into fibers and woven, Dacron becomes cloth.
When pressed into thin sheets, it becomes Mylar, which is used in
videotapes and audiotapes. Dacron polyester, mixed with other materials,
is also used in many industrial items, including motor vehi-

cle and boat bodies. Terylene and similar polyester preparations
serve the same purposes in other countries.
The production of polyester begins when monomers are mixed
in huge reactor tanks and heated, which causes them to form giant
polymer chains composed of thousands of alternating monomer
units. If T represents terphthalic acid and E represents ethylene glycol,
a small part of a necklace-like polymer can be shown in the following
way: (TETETETETE). Once each batch of polyester polymer
has the desired composition, it is processed for storage until it is
needed. In this procedure, the material, in liquid form in the hightemperature
reactor, is passed through a device that cools it and
forms solid strips. These strips are then diced, dried, and stored.
When polyester fiber is desired, the diced polyester is melted and
then forced through tiny holes in a “spinneret” device; this process
is called “extruding.” The extruded polyester cools again, while
passing through the spinneret holes, and becomes fine fibers called
“filaments.” The filaments are immediately wound into threads that
are collected in rolls. These rolls of thread are then dyed and used to
weave various fabrics. If polyester sheets or other forms of polyester
are desired, the melted, diced polyester is processed in other ways.
Polyester preparations are often mixed with cotton, glass fibers, or
other synthetic polymers to produce various products.
Impact
Polyester / 591
The development of polyester was a natural consequence of the
search for synthetic fibers that developed from work on rayon. Once
polyester had been developed, its great utility led to its widespread
use in industry. In addition, the profitability of the material spurred
efforts to produce better synthetic fibers for specific uses. One example
is that of stretchy polymers such as Helance, which is a form
of nylon. In addition, new chemical types of polymer fibers were developed,
including the polyurethane materials known collectively
as “spandex” (for example, Lycra and Vyrenet).
The wide variety of uses for polyester is amazing. Mixed with
cotton, it becomes wash-and-wear clothing; mixed with glass, it is
used to make boat and motor vehicle bodies; combined with other
materials, it is used to make roofing materials, conveyor belts,

592 / Polyester
hoses, and tire cords. In Europe, polyester has become the main
packaging material for consumer goods, and the United States does
not lag far behind in this area.
The future is sure to hold more uses for polyester and the invention
of new polymers. These spinoffs of polyester will be essential in
the development of high technology.
See also Buna rubber; Neoprene; Nylon; Orlon; Plastic; Polyethylene;
Polystyrene.
Further Reading
Furukawa, Yasu. Inventing Polymer Science: Staudinger, Carothers, and
the Emergence of Macromolecular Chemistry. Philadelphia: University
of Pennsylvania Press, 1998.
Handley, Susannah. Nylon: The Story of a Fashion Revolution, A Celebration
of Design from Art Silk to Nylon and Thinking Fibres. Baltimore:
Johns Hopkins University Press, 1999.
Hermes, Matthew E. Enough for One Lifetime: Wallace Carothers, Inventor
of Nylon. Washington, D.C.: American Chemical Society
and the Chemical Heritage Foundation, 1996.
Smith, Matthew Boyd. Polyester: The Indestructible Fashion. Atglen,
Pa.: Schiffer, 1998.

Polyethylene
Polyethylene
The invention: An artificial polymer with strong insulating properties
and many other applications.
The people behind the invention:
Karl Ziegler (1898-1973), a German chemist
Giulio Natta (1903-1979), an Italian chemist
August Wilhelm von Hofmann (1818-1892), a German chemist
The Development of Synthetic Polymers
593
In 1841, August Hofmann completed his Ph.D. with Justus von
Liebig, a German chemist and founding father of organic chemistry.
One of Hofmann’s students, William Henry Perkin, discovered that
coal tars could be used to produce brilliant dyes. The German chemical
industry, under Hofmann’s leadership, soon took the lead in
this field, primarily because the discipline of organic chemistry was
much more developed in Germany than elsewhere.
The realities of the early twentieth century found the chemical
industry struggling to produce synthetic substitutes for natural
materials that were in short supply, particularly rubber. Rubber is
a natural polymer, a material composed of a long chain of small
molecules that are linked chemically. An early synthetic rubber,
neoprene, was one of many synthetic polymers (some others were
Bakelite, polyvinyl chloride, and polystyrene) developed in the
1920’s and 1930’s. Another polymer, polyethylene, was developed
in 1936 by Imperial Chemical Industries. Polyethylene was a
tough, waxy material that was produced at high temperature and
at pressures of about one thousand atmospheres. Its method of
production made the material expensive, but it was useful as an insulating
material.
World War II and the material shortages associated with it brought
synthetic materials into the limelight. Many new uses for polymers
were discovered, and after the war they were in demand for the production
of a variety of consumer goods, although polyethylene was
still too expensive to be used widely.

594 / Polyethylene
Organometallics Provide the Key
Karl Ziegler, an organic chemist with an excellent international
reputation, spent most of his career in Germany. With his international
reputation and lack of political connections, he was a natural
candidate to take charge of the Kaiser Wilhelm Institute for Coal Research
(later renamed the Max Planck Institute) in 1943. Wise planners
saw him as a director who would be favored by the conquering
Allies. His appointment was a shrewd one, since he was allowed to
retain his position after World War II ended. Ziegler thus played a
key role in the resurgence of German chemical research after the war.
Before accepting the position at the Kaiser Wilhelm Institute,
Ziegler made it clear that he would take the job only if he could pursue
his own research interests in addition to conducting coal research.
The location of the institute in the Ruhr Valley meant that
abundant supplies of ethylene were available from the local coal industry,
so it is not surprising that Ziegler began experimenting with
that material.
Although Ziegler’s placement as head of the institute was an important
factor in his scientific breakthrough, his previous research
was no less significant. Ziegler devoted much time to the field of
organometallic compounds, which are compounds that contain a
metal atom that is bonded to one or more carbon atoms. Ziegler was
interested in organoaluminum compounds, which are compounds
that contain aluminum-carbon bonds.
Ziegler was also interested in polymerization reactions, which
involve the linking of thousands of smaller molecules into the single
long chain of a polymer. Several synthetic polymers were known,
but chemists could exert little control on the actual process. It was
impossible to regulate the length of the polymer chain, and the extent
of branching in the chain was unpredictable. It was as a result of
studying the effect of organoaluminum compounds on these chain
formation reactions that the key discovery was made.
Ziegler and his coworkers already knew that ethylene would react
with organoaluminum compounds to produce hydrocarbons,
which are compounds that contain only carbon and hydrogen and
that have varying chain lengths. Regulating the product chain length
continued to be a problem.

At this point, fate intervened in the form of a trace of nickel left in a
reactor from a previous experiment. The nickel caused the chain
lengthening to stop after two ethylene molecules had been linked.
Ziegler and his colleagues then tried to determine whether metals
other than nickel caused a similar effect with a longer polymeric
chain. Several metals were tested, and the most important finding
was that a trace of titanium chloride in the reactor caused the deposition
of large quantities of high-density polyethylene at low pressures.
Ziegler licensed the procedure, and within a year, Giulio Natta
had modified the catalysts to give high yields of polymers with
highly ordered side chains branching from the main chain. This
opened the door for the easy production of synthetic rubber. For
their discovery of Ziegler-Natta catalysts, Ziegler and Natta shared
the 1963 Nobel Prize in Chemistry.
Consequences
Polyethylene / 595
Ziegler’s process produced polyethylene that was much more
rigid than the material produced at high pressure. His product also
had a higher density and a higher softening temperature. Industrial
exploitation of the process was unusually rapid, and within ten years
more than twenty plants utilizing the process had been built throughout
Europe, producing more than 120,000 metric tons of polyethylene.
This rapid exploitation was one reason Ziegler and Natta were
awarded the Nobel Prize after such a relatively short time.
By the late 1980’s, total production stood at roughly 18 billion
pounds worldwide. Other polymeric materials, including polypropylene,
can be produced by similar means. The ready availability
and low cost of these versatile materials have radically transformed
the packaging industry. Polyethylene bottles are far lighter
than their glass counterparts; in addition, gases and liquids do not
diffuse into polyethylene very easily, and it does not break easily.
As a result, more and more products are bottled in containers
made of polyethylene or other polymers. Other novel materials
possessing properties unparalleled by any naturally occurring material
(Kevlar, for example, which is used to make bullet-resistant
vests) have also been an outgrowth of the availability of low-cost
polymeric materials.

596 / Polyethylene
See also Buna rubber; Neoprene; Nylon; Orlon; Plastic; Polyester;
Polystyrene.
Further Reading
Boor, John. Ziegler-Natta Catalysts and Polymerizations. New York:
Academic Press, 1979.
Clarke, Alison J. Tupperware: The Promise of Plastic in 1950s America.
Washington, D.C.: Smithsonian Institution Press, 1999.
Natta, Giulio. “From Stereospecific Polymerization to Asymmetric
Autocatalytic Synthesis of Macromolecules.” In Chemistry, 1963-
1970. River Edge, N.J.: World Scientific, 1999.
Ziegler, Karl. “Consequences and Development of an Invention.” In
Chemistry, 1963-1970. River Edge, N.J.: World Scientific, 1999.

Polystyrene
Polystyrene
The invention: A clear, moldable polymer with many industrial
uses whose overuse has also threatened the environment.
The people behind the invention:
Edward Simon, an American chemist
Charles Gerhardt (1816-1856), a French chemist
Marcellin Pierre Berthelot (1827-1907), a French chemist
Polystyrene Is Characterized
597
In the late eighteenth century, a scientist by the name of Casper
Neuman described the isolation of a chemical called “storax” from a
balsam tree that grew in Asia Minor. This isolation led to the first report
on the physical properties of the substance later known as “styrene.”
The work of Neuman was confirmed and expanded upon
years later, first in 1839 by Edward Simon, who evaluated the temperature
dependence of styrene, and later by Charles Gerhardt,
who proposed its molecular formula. The work of these two men
sparked an interest in styrene and its derivatives.
Polystyrene belongs to a special class of molecules known as
polymers. Apolymer (the name means “many parts”) is a giant molecule
formed by combining small molecular units, called “monomers.”
This combination results in a macromolecule whose physical
properties—especially its strength and flexibility—are significantly
different from those of its monomer components. Such polymers are
often simply called “plastics.”
Polystyrene has become an important material in modern society
because it exhibits a variety of physical characteristics that can be
manipulated for the production of consumer products. Polystyrene
is a “thermoplastic,” which means that it can be softened by heat
and then reformed, after which it can be cooled to form a durable
and resilient product.
At 94 degrees Celsius, polystyrene softens; at room temperature,
however, it rings like a metal when struck. Because of the glasslike
nature and high refractive index of polystyrene, products made

598 / Polystyrene
from it are known for their shine and attractive texture. In addition,
the material is characterized by a high level of water resistance and
by electrical insulating qualities. It is also flammable, can by dissolved
or softened by many solvents, and is sensitive to light. These
qualities make polystyrene a valuable material in the manufacture
of consumer products.
Plastics on the Market
In 1866, Marcellin Pierre Berthelot prepared styrene from ethylene
and benzene mixtures in a heated reaction flask. This was the
first synthetic preparation of polystyrene. In 1925, the Naugatuck
Chemical Company began to operate the first commercial styrene/
polystyrene manufacturing plant. In the 1930’s, the Dow Chemical
Company became involved in the manufacturing and marketing of
styrene/polystyrene products. Dow’s Styron 666 was first marketed
as a general-purpose polystyrene in 1938. This material was
the first plastic product to demonstrate polystyrene’s excellent mechanical
properties and ease of fabrication.
The advent of World War II increased the need for plastics. When
the Allies’ supply of natural rubber was interrupted, chemists sought
to develop synthetic substitutes. The use of additives with polymer
species was found to alter some of the physical properties of those
species. Adding substances called “elastomers” during the polymerization
process was shown to give a rubberlike quality to a normally
brittle species. An example of this is Dow’s Styron 475, which
was marketed in 1948 as the first “impact” polystyrene. It is called
an impact polystyrene because it also contains butadiene, which increases
the product’s resistance to breakage. The continued characterization
of polystyrene products has led to the development of a
worldwide industry that fills a wide range of consumer needs.
Following World War II, the plastics industry revolutionized
many aspects of modern society. Polystyrene is only one of the
many plastics involved in this process, but it has found its way into
a multitude of consumer products. Disposable kitchen utensils,
trays and packages, cups, videocassettes, insulating foams, egg cartons,
food wrappings, paints, and appliance parts are only a few of
the typical applications of polystyrenes. In fact, the production of

polystyrene has grown to exceed 5 billion pounds per year.
The tremendous growth of this industry in the postwar era has
been fueled by a variety of factors. Having studied the physical
and chemical properties of polystyrene, chemists and engineers
were able to envision particular uses and to tailor the manufacture
of the product to fit those uses precisely. Because of its low cost of
production, superior performance, and light weight, polystyrene
has become the material of choice for the packaging industry. The
automobile industry also enjoys its benefits. Polystyrene’s lower
density compared to those of glass and steel makes it appropriate
for use in automobiles, since its light weight means that using
it can reduce the weight of automobiles, thereby increasing gas
efficiency.
Impact
Polystyrene / 599
There is no doubt that the marketing of polystyrene has greatly
affected almost every aspect of modern society. From computer keyboards
to food packaging, the use of polystyrene has had a powerful
impact on both the quality and the prices of products. Its use is not,
however, without drawbacks; it has also presented humankind
with a dilemma. The wholesale use of polystyrene has created an
environmental problem that represents a danger to wildlife, adds to
roadside pollution, and greatly contributes to the volume of solid
waste in landfills.
Polystyrene has become a household commodity because it lasts.
The reciprocal effect of this fact is that it may last forever. Unlike natural
products, which decompose upon burial, polystyrene is very
difficult to convert into degradable forms. The newest challenge facing
engineers and chemists is to provide for the safe and efficient
disposal of plastic products. Thermoplastics such as polystyrene
can be melted down and remolded into new products, which makes
recycling and reuse of polystyrene a viable option, but this option
requires the cooperation of the same consumers who have benefited
from the production of polystyrene products.
See also Food freezing; Nylon; Orlon; Plastic; Polyester; Polyethylene;
Pyrex glass; Teflon; Tupperware.

600 / Polystyrene
Further Reading
Fenichell, Stephen. Plastic: The Making of a Synthetic Century. New
York: HarperBusiness, 1997.
Mossman, S. T. I. Early Plastics: Perspectives, 1850-1950. London: Science
Museum, 1997.
Wünsch, J. R. Polystyrene: Synthesis, Production and Applications.
Shropshire, England: Rapra Technology, 2000.

Propeller-coordinated
machine gun
Propeller-coordinated machine gun
The invention: A mechanism that synchronized machine gun fire
with propeller movement to prevent World War I fighter plane
pilots from shooting off their own propellers during combat.
The people behind the invention:
Anthony Herman Gerard Fokker (1890-1939), a Dutch-born
American entrepreneur, pilot, aircraft designer, and
manufacturer
Roland Garros (1888-1918), a French aviator
Max Immelmann (1890-1916), a German aviator
Raymond Saulnier (1881-1964), a French aircraft designer and
manufacturer
French Innovation
601
The first true aerial combat of World War I took place in 1915. Before
then, weapons attached to airplanes were inadequate for any
real combat work. Hand-held weapons and clumsily mounted machine
guns were used by pilots and crew members in attempts to
convert their observation planes into fighters. On April 1, 1915, this
situation changed. From an airfield near Dunkerque, France, a
French airman, Lieutenant Roland Garros, took off in an airplane
equipped with a device that would make his plane the most feared
weapon in the air at that time.
During a visit to Paris, Garros met with Raymond Saulnier, a French
aircraft designer. In April of 1914, Saulnier had applied for a patent on
a device that mechanically linked the trigger of a machine gun to a cam
on the engine shaft. Theoretically, such an assembly would allow the
gun to fire between the moving blades of the propeller. Unfortunately,
the available machine gun Saulnier used to test his device was a
Hotchkiss gun, which tended to fire at an uneven rate. On Garros’s arrival,
Saulnier showed him a new invention: a steel deflector shield
that, when fastened to the propeller, would deflect the small percentage
of mistimed bullets that would otherwise destroy the blade.

602 / Propeller-coordinated machine gun
The first test-firing was a disaster, shooting the propeller off and
destroying the fuselage. Modifications were made to the deflector
braces, streamlining its form into a wedge shape with gutterchannels
for deflected bullets. The invention was attached to a
Morane-Saulnier monoplane, and on April 1, Garros took off alone
toward the German lines. Success was immediate. Garros shot
down a German observation plane that morning. During the next
two weeks, Garros shot down five more German aircraft.
German Luck
The German high command, frantic over the effectiveness of the
French “secret weapon,” sent out spies to try to steal the secret and
also ordered engineers to develop a similar weapon. Luck was with
them. On April 18, 1915, despite warnings by his superiors not to fly
over enemy-held territory, Garros was forced to crash-land behind
German lines with engine trouble. Before he could destroy his aircraft,
Garros and his plane were captured by German troops. The secret
weapon was revealed.
The Germans were ecstatic about the opportunity to examine
the new French weapon. Unlike the French, the Germans had the
first air-cooled machine gun, the Parabellum, which shot continuous
bands of one hundred bullets and was reliable enough to be
adapted to a timing mechanism.
In May of 1915, Anthony Herman Gerard Fokker was shown
Garros’s captured plane and was ordered to copy the idea. Instead,
Fokker and his assistant designed a new firing system. It is unclear
whether Fokker and his team were already working on a synchronizer
or to what extent they knew of Saulnier’s previous work in
France. Within several days, however, they had constructed a working
prototype and attached it to a Fokker Eindecker 1 airplane. The
design consisted of a simple linkage of cams and push-rods connected
to the oil-pump drive of an Oberursel engine and the trigger
of a Parabellum machine gun. The firing of the gun had to be timed
precisely to fire its six hundred rounds per minute between the
twelve-hundred-revolutions-per-minute propeller blades.
Fokker took his invention to Doberitz air base, and after a series

Propeller-coordinated machine gun / 603
Anthony Herman Gerard Fokker
Anthony Fokker was born on the island of Java in the Dutch
East Indies (now Indonesia) in 1890. He returned to his parent’s
home country, the Netherlands, to attend school and then studied
aeronautics in Germany. He built his first plane in 1910 and
established Fokker Aeroplanbau near Berlin in 1912.
His monoplanes were highly esteemed when World War I
erupted in 1914, and he offered his designs to both the German
and the French governments. The Germans hired him. By the
end of the war his fighters, especially the Dr I triplane and D VII
biplane, were practically synonymous with German air warfare
because they had been the scourge of Allied pilots.
In 1922 Fokker moved to the United States and opened the
Atlantic Aircraft Corporation in New Jersey. He had lost enthusiasm
for military aircraft and turned his skills toward producing
advanced designs for civilian use. The planes his company
turned out established one first after another. His T-2 monoplane
became the first to fly nonstop from coast to coast, New
York to San Diego. His ten-seat airliner, the F VII/3m, carried
Lieutenant Commander Richard Byrd over the North Pole in
1926 and Charles Kingsford-Smith across the Pacific Ocean in
1928.
By the time Fokker died in New York in 1939, he had become
a visionary. He foresaw passenger planes as the means to knit
together the far-flung nations of the world into a network of
rapid travel and communications.
of exhausting trials before the German high command, both on the
ground and in the air, he was allowed to take two prototypes of the
machine-gun-mounted airplanes to Douai in German-held France.
At Douai, two German pilots crowded into the cockpit with Fokker
and were given demonstrations of the plane’s capabilities. The airmen
were Oswald Boelcke, a test pilot and veteran of forty reconnaissance
missions, and Max Immelmann, a young, skillful aviator
who was assigned to the front.
When the first combat-ready versions of Fokker’s Eindecker 1
were delivered to the front lines, one was assigned to Boelcke, the
other to Immelmann. On August 1, 1915, with their aerodrome un-

604 / Propeller-coordinated machine gun
der attack from nine English bombers, Boelcke and Immelmann
manned their aircraft and attacked. Boelcke’s gun jammed, and he
was forced to cut off his attack and return to the aerodrome. Immelmann,
however, succeeded in shooting down one of the bombers
with his synchronized machine gun. It was the first victory credited
to the Fokker-designed weapon system.
Impact
At the outbreak of World War I, military strategists and commanders
on both sides saw the wartime function of airplanes as a
means to supply intelligence information behind enemy lines or as
airborne artillery spotting platforms. As the war progressed and aircraft
flew more or less freely across the trenches, providing vital information
to both armies, it became apparent to ground commanders
that while it was important to obtain intelligence on enemy
movements, it was important also to deny the enemy similar information.
Early in the war, the French used airplanes as strategic bombing
platforms. As both armies began to use their air forces for strategic
bombing of troops, railways, ports, and airfields, it became evident
that aircraft would have to be employed against enemy aircraft to
prevent reconnaissance and bombing raids.
With the invention of the synchronized forward-firing machine
gun, pilots could use their aircraft as attack weapons. A pilot finally
could coordinate control of his aircraft and his armaments with
maximum efficiency. This conversion of aircraft from nearly passive
observation platforms to attack fighters is the single greatest innovation
in the history of aerial warfare. The development of fighter
aircraft forced a change in military strategy, tactics, and logistics and
ushered in the era of modern warfare. Fighter planes are responsible
for the battle-tested military adage: Whoever controls the sky controls
the battlefield.
See also Airplane; Radar; Stealth aircraft.

Further Reading
Propeller-coordinated machine gun / 605
Dierikx, M. L. J. Fokker: A Transatlantic Biography. Washington:
Smithsonian Institution Press, 1997.
Franks, Norman L. R. Aircraft Versus Aircraft: The Illustrated Story of
Fighter Pilot Combat from 1914 to the Present Day. New York:
Barnes & Noble Books, 1999.
Guttman, Jon. Fighting Firsts: Fighter Aircraft Combat Debuts from
1914 to 1944. London: Cassell, 2000.

606
Pyrex glass
Pyrex glass
The invention: A superhard and durable glass product with widespread
uses in industry and home products.
The people behind the invention:
Jesse T. Littleton (1888-1966), the chief physicist of Corning
Glass Works’ research department
Eugene G. Sullivan (1872-1962), the founder of Corning’s
research laboratories
William C. Taylor (1886-1958), an assistant to Sullivan
Cooperating with Science
By the twentieth century, Corning Glass Works had a reputation
as a corporation that cooperated with the world of science to improve
existing products and develop new ones. In the 1870’s, the
company had hired university scientists to advise on improving the
optical quality of glasses, an early example of today’s common practice
of academics consulting for industry.
When Eugene G. Sullivan established Corning’s research laboratory
in 1908 (the first of its kind devoted to glass research), the task
that he undertook with William C. Taylor was that of making a heatresistant
glass for railroad lantern lenses. The problem was that ordinary
flint glass (the kind in bottles and windows, made by melting
together silica sand, soda, and lime) has a fairly high thermal expansion,
but a poor heat conductivity. The glass thus expands
unevenly when exposed to heat. This condition can cause the glass
to break, sometimes violently. Colored lenses for oil or gas railroad
signal lanterns sometimes shattered if they were heated too much
by the flame that produced the light and were then sprayed by rain
or wet snow. This changed a red “stop” light to a clear “proceed”
signal and caused many accidents or near misses in railroading in
the late nineteenth century.
Two solutions were possible: to improve the thermal conductivity
or reduce the thermal expansion. The first is what metals do:
When exposed to heat, most metals have an expansion much greater

than that of glass, but they conduct heat so quickly that they expand
nearly equally throughout and seldom lose structural integrity from
uneven expansion. Glass, however, is an inherently poor heat conductor,
so this approach was not possible.
Therefore, a formulation had to be found that had little or no
thermal expansivity. Pure silica (one example is quartz) fits this description,
but it is expensive and, with its high melting point, very
difficult to work.
The formulation that Sullivan and Taylor devised was a borosilicate
glass—essentially a soda-lime glass with the lime replaced by
borax, with a small amount of alumina added. This gave the low thermal
expansion needed for signal lenses. It also turned out to have
good acid-resistance, which led to its being used for the battery jars
required for railway telegraph systems and other applications. The
glass was marketed as “Nonex” (for “nonexpansion glass”).
From the Railroad to the Kitchen
Pyrex glass / 607
Jesse T. Littleton joined Corning’s research laboratory in 1913.
The company had a very successful lens and battery jar material,
but no one had even considered it for cooking or other heat-transfer
applications, because the prevailing opinion was that glass absorbed
and conducted heat poorly. This meant that, in glass pans,
cakes, pies, and the like would cook on the top, where they were exposed
to hot air, but would remain cold and wet (or at least undercooked)
next to the glass surface. As a physicist, Littleton knew that
glass absorbed radiant energy very well. He thought that the heatconduction
problem could be solved by using the glass vessel itself
to absorb and distribute heat. Glass also had a significant advantage
over metal in baking. Metal bakeware mostly reflects radiant energy
to the walls of the oven, where it is lost ultimately to the surroundings.
Glass would absorb this radiation energy and conduct it evenly to
the cake or pie, giving a better result than that of the metal bakeware.
Moreover, glass would not absorb and carry over flavors from
one baking effort to the next, as some metals do.
Littleton took a cut-off battery jar home and asked his wife to
bake a cake in it. He took it to the laboratory the next day, handing
pieces around and not disclosing the method of baking until all had

608 / Pyrex glass
Jesse T. Littleton
To prove that glass is good for baking, place an uncooked pie
in a pie tin and place another pie pan under it, made half of tin
and half of non-expanding glass. Place it in all the oven. That is
the experiment Jesse Talbot Littleton, Jr., used at Corning Glass
Works soon after he hired on in 1913. The story behind it began
with a ceramic dish that cracked when his wife baked a cake.
That would not happen, he realized, with the right kind of
glass. Although his wife baked a cake successfully in a glass
battery jar bottom at his request, Littleton had to demonstrate
the feat for his superiors scientifically. The half of the pie over
the glass, it turned out, cooked faster and more evenly. Kitchen
glassware was born.
Littleton was born in Belle Haven, Virginia, in 1888. After
taking degrees from Southern University and Tulane University,
he earned a doctorate in physics from the University of
Wisconsin in 1911. He briefly vowed to remain a bachelor and
dedicate his life to physics, but Besse Cook, a pretty Mississippi
school teacher, turned his head, and so he got married instead.
He was the first physicist added to the newly organized research
laboratories at Corning in New York. There he studied
practical problems involved in the industrial applications of
glass, including tempering, and helped invent a gas pressure
meter to measure the flow of air in blowing glass and a sensitive,
faster thermometer. He rose rapidly in the organization. In
1920 he became chief of the physical lab, assistant director of research
in 1940, vice president in 1943, director of all Corning research
and development in 1946, and general technical adviser
in 1951.
Littleton retired a year later and, a passionate outdoorsman,
devoted himself to hunting and fishing. A leading figure in the
ceramics industry, he belonged to the American Academy for
the Advancement of Science, American Physical Society, and
the American Institute of Engineers and was an editor for the
Journal of Applied Physics. He died in 1966.

agreed that the results were excellent. With this agreement, he was
able to commit laboratory time to developing variations on the
Nonex formula that were more suitable for cooking. The result was
Pyrex, patented and trademarked in May of 1915.
Impact
Pyrex glass / 609
In the 1930’s, Pyrex “Flameware” was introduced, with a new
glass formulation that could resist the increased heat of stovetop
cooking. In the half century since Flameware was introduced,
Corning went on to produce a variety of other products and materials:
tableware in tempered opal glass; cookware in Pyroceram, a
glass product that during heat treatment gained such mechanical
strength as to be virtually unbreakable; even hot plates and stoves
topped with Pyroceram.
In the same year that Pyrex was marketed for cooking, it was
also introduced for laboratory apparatus. Laboratory glassware
had been coming from Germany at the beginning of the twentieth
century; World War I cut off the supply. Corning filled the gap
with Pyrex beakers, flasks, and other items. The delicate blownglass
equipment that came from Germany was completely displaced
by the more rugged and heat-resistant machine-made Pyrex
ware.
Any number of operations are possible with Pyrex that cannot
be performed safely in flint glass: Test tubes can be thrust directly
into burner flames, with no preliminary warming; beakers and
flasks can be heated on hot plates; and materials that dissolve
when exposed to heat can be made into solutions directly in Pyrex
storage bottles, a process that cannot be performed in regular
glass. The list of such applications is almost endless.
Pyrex has also proved to be the material of choice for lenses in
the great reflector telescopes, beginning in 1934 with that at Mount
Palomar. By its nature, astronomical observation must be done
with the scope open to the weather. This means that the mirror
must not change shape with temperature variations, which rules
out metal mirrors. Silvered (or aluminized) Pyrex serves very well,
and Corning has developed great expertise in casting and machining
Pyrex blanks for mirrors of all sizes.

610 / Pyrex glass
See also Laminated glass; Microwave cooking; Plastic; Polystyrene;
Teflon; Tupperware.
Further Reading
Blaszczyk, Regina Lee. Imagining Consumers: Design and Innovation
from Wedgwood to Corning. Baltimore: Johns Hopkins University
Press, 2000.
Graham, Margaret B. W., and Alec T. Shuldiner. Corning and the Craft
of Innovation. New York: Oxford University Press, 2001.
Stage, Sarah, and Virginia Bramble Vincenti. Rethinking Home Economics:
Women and the History of a Profession. Ithaca, N.Y.: Cornell
University Press, 1997.
Rogove, Susan Tobier, and Marcia B. Steinhauer. Pyrex by Corning: A
Collector’s Guide. Marietta, Ohio: Antique Publications, 1993.

Radar
Radar
The invention: An electronic system for detecting objects at great
distances, radar was a major factor in the Allied victory of World
War II and now pervades modern life, including scientific research.
The people behind the invention:
Sir Robert Watson-Watt (1892-1973), the father of radar who
proposed the chain air-warning system
Arnold F. Wilkins, the person who first calculated the intensity
of a radio wave
William C. Curtis (1914-1976), an American engineer
Looking for Thunder
611
Sir Robert Watson-Watt, a scientist with twenty years of experience
in government, led the development of the first radar, an acronym
for radio detection and ranging. “Radar” refers to any instrument
that uses the reflection of radio waves to determine the
distance, direction, and speed of an object.
In 1915, during World War I (1914-1918), Watson-Watt joined
Great Britain’s Meteorological Office. He began work on the detection
and location of thunderstorms at the Royal Aircraft Establishment
in Farnborough and remained there throughout the
war. Thunderstorms were known to be a prolific source of “atmospherics”
(audible disturbances produced in radio receiving apparatus
by atmospheric electrical phenomena), and Watson-Watt
began the design of an elementary radio direction finder that
gave the general position of such storms. Research continued after
the war and reached a high point in 1922 when sealed-off
cathode-ray tubes first became available. With assistance from
J. F. Herd, a fellow Scot who had joined him at Farnborough, he
constructed an instantaneous direction finder, using the new
cathode-ray tubes, that gave the direction of thunderstorm activity.
It was admittedly of low sensitivity, but it worked, and it was
the first of its kind.

612 / Radar
William C. Curtis
In addition to radar’s applications in navigation, civil aviation,
and science, it rapidly became an integral part of military
aircraft by guiding weaponry and detecting enemy aircraft and
missiles. The research and development industry that grew to
provide offensive and defensive systems greatly expanded the
opportunities for young scientists during the Cold War. Among
them was William C. Curtis (1914-1976), one of the most influential
African Americans in defense research.
Curtis graduated from the Tuskegee Institute (later Tuskegee
University), where he later served as its first dean of engineering.
While there, he helped form and train the Tuskegee
Airmen, a famous squadron of African American fighter pilots
during World War II. He also worked for the Radio Corporation
of American (RCA) for twenty-three years. It was while at RCA
that he contributed innovations to military radar. These include
the Black Cat weapons system, MG-3 fire control system, 300-A
weapon radar system, and Airborne Interceptor Data Link.
Watson-Watt did much of this work at a new site at Ditton Park,
near Slough, where the National Physical Laboratory had a field
station devoted to radio research. In 1927, the two endeavors were
combined as the Radio Research Station; it came under the general
supervision of the National Physical Laboratory, with Watson-Watt
as the first superintendent. This became a center with unrivaled expertise
in direction finding using the cathode-ray tube and in studying
the ionosphere using radio waves. No doubt these facilities
were a factor when Watson-Watt invented radar in 1935.
As radar developed, its practical uses expanded. Meteorological
services around the world, using ground-based radar, gave warning
of approaching rainstorms. Airborne radars proved to be a great
help to aircraft by allowing them to recognize potentially hazardous
storm areas. This type of radar was used also to assist research into
cloud and rain physics. In this type of research, radar-equipped research
aircraft observe the radar echoes inside a cloud as rain develops,
and then fly through the cloud, using on-board instruments to
measure the water content.

Technician at a modern radar display. (PhotoDisc)

614 / Radar
Aiming Radar at the Moon
The principles of radar were further developed through the discipline
of radio astronomy. This field began with certain observations
made by the American electrical engineer Karl Jansky in 1933
at the Bell Laboratories at Holmdell, New Jersey. Radio astronomers
learn about objects in space by intercepting the radio waves that
these objects emit.
Jansky found that radio signals were coming to Earth from space.
He called these mysterious pulses “cosmic noise.” In particular, there
was an unusual amount of radar noise when the radio antennas were
pointed at the Sun, which increased at the time of sun-spot activity.
All this information lay dormant until after World War II (1939-
1945), at which time many investigators turned their attention to interpreting
the cosmic noise. The pioneers were Sir Bernard Lovell at
Manchester, England, Sir Martin Ryle at Cambridge, England, and
Joseph Pawsey of the Commonwealth of Science Industrial Research
Organization, in Australia. The intensity of these radio waves was
first calculated by Arnold F. Wilkins.
As more powerful tools became available toward the end of
World War II, curiosity caused experimenters to try to detect radio
signals from the Moon. This was accomplished successfully in the
late 1940’s and led to experiments on other objects in the solar system:
planets, satellites, comets, and asteroids.
Impact
Radar introduced some new and revolutionary concepts into warfare,
and in doing so gave birth to entirely new branches of technology.
In the application of radar to marine navigation, the long-range
navigation system developed during the war was taken up at once
by the merchant fleets that used military-style radar equipment
without modification. In addition, radar systems that could detect
buoys and other ships and obstructions in closed waters, particularly
under conditions of low visibility, proved particularly useful
to peacetime marine navigation.
In the same way, radar was adopted to assist in the navigation of
civil aircraft. The various types of track guidance systems devel-

oped after the war were aimed at guiding aircraft in the critical last
hundred kilometers or so of their run into an airport. Subsequent
improvements in the system meant that an aircraft could place itself
on an approach or landing path with great accuracy.
The ability of radar to measure distance to an extraordinary degree
of accuracy resulted in the development of an instrument that
provided pilots with a direct measurement of the distances between
airports. Along with these aids, ground-based radars were developed
for the control of aircraft along the air routes or in the airport
control area.
The development of electronic computers can be traced back to
the enormous advances in circuit design, which were an integral part
of radar research during the war. During that time, some elements
of electronic computing had been built into bombsights and other
weaponry; later, it was realized that a whole range of computing operations
could be performed electronically. By the end of the war,
many pulse-forming networks, pulse-counting circuits, and memory
circuits existed in the form needed for an electronic computer.
Finally, the developing radio technology has continued to help
astronomers explore the universe. Large radio telescopes exist in almost
every country and enable scientists to study the solar system
in great detail. Radar-assisted cosmic background radiation studies
have been a building block for the big bang theory of the origin of
the universe.
See also Airplane; Cruise missile; Radio interferometer; Sonar;
Stealth aircraft.
Further Reading
Radar / 615
Brown, Louis. A Radar History of World War II: Technical and Military
Imperatives. Philadelphia: Institute of Physics, 1999.
Latham, Colin, and Anne Stobbs. Pioneers of Radar. Gloucestershire:
Sutton, 1999.
Rowland, John. The Radar Man: The Story of Sir Robert Watson-Watt.
New York: Roy Publishers, 1964.
Watson-Watt, Robert Alexander. The Pulse of Radar: The Autobiography
of Sir Robert Watson-Watt. New York: Dial Press, 1959.

616
Radio
Radio
The invention: The first radio transmissions of music and voice
laid the basis for the modern radio and television industries.
The people behind the invention:
Guglielmo Marconi (1874-1937), an Italian physicist and
inventor
Reginald Aubrey Fessenden (1866-1932), an American radio
pioneer
True Radio
The first major experimenter in the United States to work with
wireless radio was Reginald Aubrey Fessenden. This transplanted
Canadian was a skilled, self-made scientist, but unlike American inventor
Thomas Alva Edison, he lacked the business skills to gain the
full credit and wealth that such pathbreaking work might have merited.
Guglielmo Marconi, in contrast, is most often remembered as
the person who invented wireless (as opposed to telegraphic) radio.
There was a great difference between the contributions of Marconi
and Fessenden. Marconi limited himself to experiments with
radio telegraphy; that is, he sought to send through the air messages
that were currently being sent by wire—signals consisting of dots
and dashes. Fessenden sought to perfect radio telephony, or voice
communication by wireless transmission. Fessenden thus pioneered
the essential precursor of modern radio broadcasting. At the beginning
of the twentieth century, Fessenden spent much time and energy
publicizing his experiments, thus promoting interest in the
new science of radio broadcasting.
Fessenden began his career as an inventor while working for the
U.S. Weather Bureau. He set out to invent a radio system by which
to broadcast weather forecasts to users on land and at sea. Fessenden
believed that his technique of using continuous waves in the
radio frequency range (rather than interrupted waves Marconi had
used to produce the dots and dashes of Morse code) would provide
the power necessary to carry Morse telegraph code yet be effective
enough to handle voice communication. He would turn out to be

correct. He conducted experiments as early as 1900 at Rock Point,
Maryland, about 80 kilometers south of Washington, D.C., and registered
his first patent in the area of radio research in 1902.
Fame and Glory
Radio / 617
In 1900, Fessenden asked the General Electric Company to produce
a high-speed generator of alternating current—or alternator—
to use as the basis of his radio transmitter. This proved to be the first
major request for wireless radio apparatus that could project voices
and music. It took the engineers three years to design and deliver
the alternator. Meanwhile, Fessenden worked on an improved radio
receiver. To fund his experiments, Fessenden aroused the interest
of financial backers, who put up one million dollars to create the
National Electric Signalling Company in 1902.
Fessenden, along with a small group of handpicked scientists,
worked at Brant Rock on the Massachusetts coast south of Boston.
Working outside the corporate system, Fessenden sought fame and
glory based on his own work, rather than on something owned by a
corporate patron.
Fessenden’s moment of glory came on December 24, 1906, with
the first announced broadcast of his radio telephone. Using an ordinary
telephone microphone and his special alternator to generate
the necessary radio energy, Fessenden alerted ships up and down
the Atlantic coast with his wireless telegraph and arranged for
newspaper reporters to listen in from New York City. Fessenden
made himself the center of the show. He played the violin, sang,
and read from the Bible. Anticipating what would become standard
practice fifty years later, Fessenden also transmitted the sounds of a
phonograph recording. He ended his first broadcast by wishing those
listening “a Merry Christmas.” A similar, equally well-publicized
demonstration came on December 31.
Although Fessenden was skilled at drawing attention to his invention
and must be credited, among others, as one of the engineering
founders of the principles of radio, he was far less skilled at
making money with his experiments, and thus his long-term impact
was limited. The National Electric Signalling Company had a fine
beginning and for a time was a supplier of equipment to the United

618 / Radio
Fruit Company. The financial panic of 1907, however, wiped out an
opportunity to sell the Fessenden patents—at a vast profit—to a corporate
giant, the American Telephone and Telegraph Corporation.
Impact
Had there been more receiving equipment available and in place,
a massive audience could have heard Fessenden’s first broadcast.
He had the correct idea, even to the point of playing a crude phonograph
record. Yet Fessenden, Marconi, and their rivals were unable
to establish a regular series of broadcasts. Their “stations” were experimental
and promotional.
It took the stresses of World War I to encourage broader use of
wireless radio based on Fessenden’s experiments. Suddenly, communicating
from ship to ship or from a ship to shore became a frequent
matter of life or death. Generating publicity was no longer
necessary. Governments fought over crucial patent rights. The Radio
Corporation of America (RCA) pooled vital knowledge. Ultimately,
RCA came to acquire the Fessenden patents. Radio broadcasting
commenced, and the radio industry, with its multiple uses
for mass communication, was off and running.
Antique tabletop radio. (PhotoDisc)

Guglielmo Marconi
Guglielmo Marconi failed his entrance examinations to the
University of Bologna in 1894. He had a weak educational background,
particularly in science, but he was not about to let
that—or his father’s disapproval—stop him after he conceived
a deep interest in wireless telegraphy during his teenage years.
Marconi was born in 1874 to a wealthy Italian landowner
and an Irish whiskey distiller’s daughter and grew up both in
Italy and England. His parents provided tutors for
him, but he and his brother often accompanied their
mother, a socialite, on extensive travels. He acquired
considerable social skills, easy self-confidence, and
determination from the experience.
Thus, when he failed his exams, he simply tried another
route for his ambitions. He and his mother persuaded
a science professor to let Marconi use a university
laboratory unofficially. His father thought it a
waste of time. However, he changed his mind when
his son succeeded in building equipment that could
transmit electronic signals around their house without wires, an
achievement right at the vanguard of technology.
Now supported by his father’s money, Marconi and his
brother built an elaborate set of equipment—including an oscillator,
coherer, galvanometer, and antennas—that they hoped
would send a signal outside over a long distance. His brother
walked off a mile and a half, out of sight, with the galvanometer
and a rifle. When the galvanometer moved, indicating a signal
had arrived from the oscillator, he fired the rifle to let Marconi
know he had succeeded. The incident is widely cited as the first
radio transmission.
Marconi went on to send signals over greater and greater
distances. He patented a tuner to permit transmissions at specific
frequencies, and he started the Wireless Telegraph and Signal
Company to bring his inventions to the public; its American
branch was the Radio Corporation of America (RCA). He not
only grew wealthy at a young age; he also was awarded half of
the 1909 Nobel Prize in Physics for his work. He died in Rome
in 1937, one of the most famous inventors in the world.
Radio / 619
(Library of Congress)

620 / Radio
See also Communications satellite; Compact disc; Dolby noise
reduction; FM radio; Long-distance radiotelephony; Radio crystal
sets; Television; Transistor; Transistor radio.
Further Reading
Fessenden, and Helen May Trott. Fessenden: Builder of Tomorrows.
New York: Arno Press, 1974.
Lewis, Tom. Empire of the Air: The Men Who Made Radio. New York:
HarperPerennial, 1993.
Masini, Giancarlo. Marconi. New York: Marsilio Publishers, 1995.
Seitz. Frederick. The Cosmic Inventor: Reginald Aubrey Fessenden,
1866-1932. Philadelphia: American Philosophical Society, 1999.

Radio crystal sets
Radio crystal sets
The invention: The first primitive radio receivers, crystal sets led
to the development of the modern radio.
The people behind the invention:
H. H. Dunwoody (1842-1933), an American inventor
Sir John A. Fleming (1849-1945), a British scientist-inventor
Heinrich Rudolph Hertz (1857-1894), a German physicist
Guglielmo Marconi (1874-1937), an Italian engineer-inventor
James Clerk Maxwell (1831-1879), a Scottish physicist
Greenleaf W. Pickard (1877-1956), an American inventor
From Morse Code to Music
621
In the 1860’s, James Clerk Maxwell demonstrated that electricity
and light had electromagnetic and wave properties. The conceptualization
of electromagnetic waves led Maxwell to propose that
such waves, made by an electrical discharge, would eventually be
sent long distances through space and used for communication
purposes. Then, near the end of the nineteenth century, the technology
that produced and transmitted the needed Hertzian (or radio)
waves was devised by Heinrich Rudolph Hertz, Guglielmo Marconi
(inventor of the wireless telegraph), and many others. The resultant
radio broadcasts, however, were limited to the dots and
dashes of the Morse code.
Then, in 1901, H. H. Dunwoody and Greenleaf W. Pickard invented
the crystal set. Crystal sets were the first radio receivers
that made it possible to hear music and the many other types of
now-familiar radio programs. In addition, the simple construction
of the crystal set enabled countless amateur radio enthusiasts
to build “wireless receivers” (the name for early radios) and
to modify them. Although, except as curiosities, crystal sets were
long ago replaced by more effective radios, they are where it all
began.

622 / Radio crystal sets
Crystals, Diodes, Transistors, and Chips
Radio broadcasting works by means of electromagnetic radio
waves, which are low-energy cousins of light waves. All electromagnetic
waves have characteristic vibration frequencies and wavelengths.
This article will deal mostly with long radio waves of frequencies
from 550 to 1,600 kilocycles (kilohertz), which can be seen
on amplitude-modulation (AM) radio dials. Frequency-modulation
(FM), shortwave, and microwave radio transmission use higherenergy
radio frequencies.
The broadcasting of radio programs begins with the conversion
of sound to electrical impulses by means of microphones. Then, radio
transmitters turn the electrical impulses into radio waves that
are broadcast together with higher-energy carrier waves. The combined
waves travel at the speed of light to listeners. Listeners hear
radio programs by using radio receivers that pick up broadcast
waves through antenna wires and reverse the steps used in broadcasting.
This is done by converting those waves to electrical impulses
and then into sound waves. The two main types of radio
broadcasting are AM and FM, which allow the selection (modulation)
of the power (amplitude) or energy (frequency) of the broadcast
waves.
The crystal set radio receiver of Dunwoody and Pickard had
many shortcomings. These led to the major modifications that produced
modern radios. Crystal sets, however, began the radio industry
and fostered its development. Today, it is possible to purchase
somewhat modified forms of crystal sets, as curiosity items. All
crystal sets, original or modern versions, are crude AM radio receivers
that are composed of four components: an antenna wire, a crystal
detector, a tuning circuit, and a headphone or loudspeaker.
Antenna wires (aerials) pick up radio waves broadcast by external
sources. Originally simple wires, today’s aerials are made to
work better by means of insulation and grounding. The crystal detector
of a crystal set is a mineral crystal that allows radio waves to
be selected (tuned). The original detectors were crystals of a leadsulfur
mineral, galena. Later, other minerals (such as silicon and carborundum)
were also found to work. The tuning circuit is composed
of 80 to 100 turns of insulated wire, wound on a 0.33-inch

support. Some surprising supports used in homemade tuning circuits
include cardboard toilet-paper-roll centers and Quaker Oats
cereal boxes. When realism is desired in collector crystal sets, the
coil is usually connected to a wire probe selector called a “cat’s
whisker.” In some such crystal sets, a condenser (capacitor) and additional
components are used to extend the range of tunable signals.
Headphones convert chosen radio signals to sound waves that are
heard by only one listener. If desired, loudspeakers can be used to
enable a roomful of listeners to hear chosen programs.
An interesting characteristic of the crystal set is the fact that its
operation does not require an external power supply. Offsetting
this are its short reception range and a great difficulty in tuning or
maintaining tuned-in radio signals. The short range of these radio
receivers led to, among other things, the use of power supplies
(house current or batteries) in more sophisticated radios. Modern
solutions to tuning problems include using manufactured diode
vacuum tubes to replace crystal detectors, which are a kind of natural
diode. The first manufactured diodes, used in later crystal sets
and other radios, were invented by John Ambrose Fleming, a colleague
of Marconi’s. Other modifications of crystal sets that led to
more sophisticated modern radios include more powerful aerials,
better circuits, and vacuum tubes. Then came miniaturization,
which was made possible by the use of transistors and silicon chips.
Impact
Radio crystal sets / 623
The impact of the invention of crystal sets is almost incalculable,
since they began the modern radio industry. These early radio receivers
enabled countless radio enthusiasts to build radios, to receive radio
messages, and to become interested in developing radio communication
systems. Crystal sets can be viewed as having spawned all
the variant modern radios. These include boom boxes and other portable
radios; navigational radios used in ships and supersonic jet
airplanes; and the shortwave, microwave, and satellite networks
used in the various aspects of modern communication.
The later miniaturization of radios and the development of sophisticated
radio system components (for example, transistors
and silicon chips) set the stage for both television and computers.

624 / Radio crystal sets
Certainly, if one tried to assess the ultimate impact of crystal sets by
simply counting the number of modern radios in the United States,
one would find that few Americans more than ten years old own
fewer than two radios. Typically, one of these is run by house electric
current and the other is a portable set that is carried almost everywhere.
See also FM radio; Long-distance radiotelephony; Radio; Television;
Transistor radio.
Further Reading
Masini, Giancarlo. Marconi. New York: Marsilio, 1995.
Sievers, Maurice L. Crystal Clear: Vintage American Crystal Sets, Crystal
Detectors, and Crystals. Vestal, N.Y.: Vestal Press, 1991.
Tolstoy, Ivan. James Clerk Maxwell: A Biography. Chicago: University
of Chicago Press, 1982.

Radio interferometer
Radio interferometer
The invention: An astronomical instrument that combines multiple
radio telescopes into a single system that makes possible the
exploration of distant space.
The people behind the invention:
Sir Martin Ryle (1918-1984), an English astronomer
Karl Jansky (1905-1950), an American radio engineer
Hendrik Christoffel van de Hulst (1918- ), a Dutch radio
astronomer
Harold Irving Ewan (1922- ), an American astrophysicist
Edward Mills Purcell (1912-1997), an American physicist
Seeing with Radio
625
Since the early 1600’s, astronomers have relied on optical telescopes
for viewing stellar objects. Optical telescopes detect the
visible light from stars, galaxies, quasars, and other astronomical
objects. Throughout the late twentieth century, astronomers developed
more powerful optical telescopes for peering deeper into the
cosmos and viewing objects located hundreds of millions of lightyears
away from the earth.
In 1933, Karl Jansky, an American radio engineer with Bell Telephone
Laboratories, constructed a radio antenna receiver for locating
sources of telephone interference. Jansky discovered a daily radio
burst that he was able to trace to the center of the Milky Way
galaxy. In 1935, Grote Reber, another American radio engineer, followed
up Jansky’s work with the construction of the first dishshaped
“radio” telescope. Reber used his 9-meter-diameter radio
telescope to repeat Jansky’s experiments and to locate other radio
sources in space. He was able to map precisely the locations of various
radio sources in space, some of which later were identified as
galaxies and quasars.
Following World War II (that is, after 1945), radio astronomy
blossomed with the help of surplus radar equipment. Radio astronomy
tries to locate objects in space by picking up the radio waves

626 / Radio interferometer
that they emit. In 1944, the Dutch astronomer Hendrik Christoffel
van de Hulst had proposed that hydrogen atoms emit radio waves
with a 21-centimeter wavelength. Because hydrogen is the most
abundant element in the universe, van de Hulst’s discovery had explained
the nature of extraterrestrial radio waves. His theory later
was confirmed by the American radio astronomers Harold Irving
Ewen and Edward Mills Purcell of Harvard University.
By coupling the newly invented computer technology with radio
telescopes, astronomers were able to generate a radio image of a star
almost identical to the star’s optical image. A major advantage of radio
telescopes over optical telescopes is the ability of radio telescopes
to detect extraterrestrial radio emissions day or night, as well as their
ability to bypass the cosmic dust that dims or blocks visible light.
More with Less
After 1945, major research groups were formed in England, Australia,
and The Netherlands. Sir Martin Ryle was head of the Mullard
Radio Astronomy Observatory of the Cavendish Laboratory,
University of Cambridge. He had worked with radar for the Telecommunications
Research Establishment during World War II.
The radio telescopes developed by Ryle and other astronomers
operate on the same basic principle as satellite television receivers.
A constant stream of radio waves strikes the parabolic-shaped reflector
dish, which aims all the radio waves at a focusing point
above the dish. The focusing point directs the concentrated radio
beam to the center of the dish, where it is sent to a radio receiver,
then an amplifier, and finally to a chart recorder or computer.
With large-diameter radio telescopes, astronomers can locate
stars and galaxies that cannot be seen with optical telescopes. This
ability to detect more distant objects is called “resolution.” Like
optical telescopes, large-diameter radio telescopes have better resolution
than smaller ones. Very large radio telescopes were constructed
in the late 1950’s and early 1960’s (Jodrell Bank, England;
Green Bank, West Virginia; Arecibo, Puerto Rico). Instead of just
building larger radio telescopes to achieve greater resolution, however,
Ryle developed a method called “interferometry.” In Ryle’s
method, a computer is used to combine the incoming radio waves

Moving
Spacecraft
Angular
Separation Fixed
Radio interferometer / 627
Radio Star
(Quasar)
California Spain
One use of VLBI is to navigate a spacecraft: By measuring the angular separation between a
fixed radio star, such as a quasar, and a moving spacecraft, the craft’s location, orientation,
and path can be precisely monitored and adjusted.
of two or more movable radio telescopes pointed at the same stellar
object.
Suppose that one had a 30-meter-diameter radio telescope. Its radio
wave-collecting area would be limited to its diameter. If a second
identical 30-meter-diameter radio telescope was linked with
the first, then one would have an interferometer. The two radio telescopes
would point exactly at the same stellar object, and the radio
emissions from this object captured by the two telescopes would be
combined by computer to produce a higher-resolution image. If the
two radio telescopes were located 1.6 kilometers apart, then their
combined resolution would be equivalent to that of a single radio
telescope dish 1.6 kilometers in diameter.
Ryle constructed the first true radio telescope interferometer at
the Mullard Radio Astronomy Observatory in 1955. He used combinations
of radio telescopes to produce interferometers containing
about twelve radio receivers. Ryle’s interferometer greatly improved
radio telescope resolution for detecting stellar radio sources, mapping
the locations of stars and galaxies, assisting in the discovery of

628 / Radio interferometer
“quasars” (quasi-stellar radio sources), measuring the earth’s rotation
around the Sun, and measuring the motion of the solar system
through space.
Consequences
Following Ryle’s discovery, interferometers were constructed at
radio astronomy observatories throughout the world. The United
States established the National Radio Astronomy Observatory (NRAO)
in rural Green Bank, West Virginia. The NRAO is operated by nine
eastern universities and is funded by the National Science Foundation.
At Green Bank, a three-telescope interferometer was constructed,
with each radio telescope having a 26-meter-diameter
dish. During the late 1970’s, the NRAO constructed the largest radio
interferometer in the world, the Very Large Array (VLA). The VLA,
located approximately 80 kilometers west of Socorro, New Mexico,
consists of twenty-seven 25-meter-diameter radio telescopes linked
by a supercomputer. The VLA has a resolution equivalent to that of
a single radio telescope 32 kilometers in diameter.
Even larger radio telescope interferometers can be created with
a technique known as “very long baseline interferometry” (VLBI).
VLBI has been used to construct a radio telescope having an effective
diameter of several thousand kilometers. Such an arrangement
involves the precise synchronization of radio telescopes located
in several different parts of the world. Supernova 1987A in
the Large Magellanic Cloud was studied using a VLBI arrangement
between observatories located in Australia, South America,
and South Africa.
Launching radio telescopes into orbit and linking them with
ground-based radio telescopes could produce a radio telescope
whose effective diameter would be larger than that of the earth.
Such instruments will enable astronomers to map the distribution
of galaxies, quasars, and other cosmic objects, to understand the
origin and evolution of the universe, and possibly to detect meaningful
radio signals from extraterrestrial civilizations.
See also Neutrino detector; Weather satellite; Artificial satellite;
Communications satellite; Radar; Rocket; Weather satellite.

Further Reading
Radio interferometer / 629
Graham-Smith, Francis. Sir Martin Ryle: A Biographical Memoir. London:
Royal Society, 1987.
Malphrus, Benjamin K. The History of Radio Astronomy and the National
Radio Astronomy Observatory: Evolution Toward Big Science.
Malabar, Fla.: Krieger, 1996.
Pound, Robert V. Edward Mills Purcell: August 30, 1912-March 7,
1997. Washington, D.C.: National Academy Press, 2000.

630
Refrigerant gas
Refrigerant gas
The invention: A safe refrigerant gas for domestic refrigerators,
dichlorodifluoromethane helped promote a rapid growth in the
acceptance of electrical refrigerators in homes.
The people behind the invention:
Thomas Midgley, Jr. (1889-1944), an American engineer and
chemist
Charles F. Kettering (1876-1958), an American engineer and
inventor who was the head of research for General Motors
Albert Henne (1901-1967), an American chemist who was
Midgley’s chief assistant
Frédéric Swarts (1866-1940), a Belgian chemist
Toxic Gases
Refrigerators, freezers, and air conditioners have had a major impact
on the way people live and work in the twentieth century. With
them, people can live more comfortably in hot and humid areas,
and a great variety of perishable foods can be transported and
stored for extended periods. As recently as the early nineteenth century,
the foods most regularly available to Americans were bread
and salted meats. Items now considered essential to a balanced diet,
such as vegetables, fruits, and dairy products, were produced and
consumed only in small amounts.
Through the early part of the twentieth century, the pattern of
food storage and distribution evolved to make perishable foods
more available. Farmers shipped dairy products and frozen meats
to mechanically refrigerated warehouses. Smaller stores and most
American households used iceboxes to keep perishable foods fresh.
The iceman was a familiar figure on the streets of American towns,
delivering large blocks of ice regularly.
In 1930, domestic mechanical refrigerators were being produced
in increasing numbers. Most of them were vapor compression machines,
in which a gas was compressed in a closed system of pipes
outside the refrigerator by a mechanical pump and condensed to a

liquid. The liquid was pumped into a sealed chamber in the refrigerator
and allowed to evaporate to a gas. The process of evaporation
removes heat from the environment, thus cooling the interior of the
refrigerator.
The major drawback of early home refrigerators involved the
types of gases used. In 1930, these included ammonia, sulfur dioxide,
and methyl chloride. These gases were acceptable if the refrigerator’s
gas pipes never sprang a leak. Unfortunately, leaks sometimes
occurred, and all these gases are toxic. Ammonia and sulfur
dioxide both have unpleasant odors; if they leaked, at least they
would be detected rapidly. Methyl chloride however, can form a
dangerously explosive mixture with air, and it has only a very faint,
and not unpleasant, odor. In a hospital in Cleveland during the
1920’s, a refrigerator with methyl chloride leaked, and there was a
disastrous explosion of the methyl chloride-air mixture. After that,
methyl chloride for use in refrigerators was mixed with a small
amount of a very bad-smelling compound to make leaks detectable.
(The same tactic is used with natural gas.)
Three-Day Success
Refrigerant gas / 631
General Motors, through its Frigidaire division, had a substantial
interest in the domestic refrigerator market. Frigidaire refrigerators
used sulfur dioxide as the refrigerant gas. Charles F. Kettering,
director of research for General Motors, decided that Frigidaire
needed a new refrigerant gas that would have good thermal properties
but would be nontoxic and nonexplosive. In early 1930, he sent
Lester S. Keilholtz, chief engineer of General Motors’ Frigidaire division,
to Thomas Midgley, Jr., a mechanical engineer and selftaught
chemist. He challenged them to develop such a new gas.
Midgley’s associates, Albert Henne and Robert McNary, researched
what types of compounds might already fit Kettering’s specifications.
Working with research that had been done by the Belgian
chemist Frédéric Swarts in the late nineteenth and early twentieth
centuries, Midgley, Henne, and McNary realized that dichlorodifluoromethane
would have ideal thermal properties and the right
boiling point for a refrigerant gas. The only question left to be answered
was whether the compound was toxic.

632 / Refrigerant gas
The chemists prepared a few grams of dichlorodifluoromethane
and put it, along with a guinea pig, into a closed chamber. They
were delighted to see that the animal seemed to suffer no ill effects
at all and was able to breathe and move normally. They were briefly
puzzled when a second batch of the compound killed a guinea pig
almost instantly. Soon, they discovered that an impurity in one of
the ingredients had produced a potent poison in their refrigerant
gas. A simple washing procedure completely removed the poisonous
contaminant.
This astonishingly successful research project was completed in
three days. The boiling point of dichlorodifluoromethane is −5.6 degrees
Celsius. It is nontoxic and nonflammable and possesses excellent
thermal properties. When Midgley was awarded the Perkin
Medal for industrial chemistry in 1937, he gave the audience a
graphic demonstration of the properties of dichlorodifluoromethane:
He inhaled deeply of its vapors and exhaled gently into a jar
containing a burning candle. The candle flame promptly went out.
This visual evidence proved that dichlorodifluoromethane was not
poisonous and would not burn.
Impact
The availability of this safe refrigerant gas, which was renamed
Freon, led to drastic changes in the United States. The current patterns
of food production, distribution, and consumption are a direct
result, as is air conditioning. Air conditioning was developed early
in the twentieth century; by the late 1970’s, most American cars and
residences were equipped with air conditioning, and other countries
with hot climates followed suit. Consequently, major relocations
of populations and businesses have become possible. Since
World War II, there have been steady migrations to the “Sun Belt,”
the states spanning the United States from southeast to southwest,
because air conditioners have made these areas much more livable.
Freon is a member of a family of chemicals called “chlorofluorocarbons.”
In addition to refrigeration, it is also used as a propellant
in aerosols and in the production of polystyrene plastics. In 1974,
scientists began to suspect that chlorofluorocarbons, when released
into the air, might have a serious effect on the environment. They

speculated that the compounds might migrate into the stratosphere,
where they could be decomposed by the intense ultraviolet light
from the sunlight that is prevented from reaching the earth’s surface
by the thin but vital layer of ozone in the stratosphere. In the process,
large amounts of the ozone layer might also be destroyed—
letting in the dangerous ultraviolet light. In addition to possible climatic
effects, the resulting increase in ultraviolet light reaching the
earth’s surface would raise the incidence of skin cancers. As a result,
chemical manufacturers are trying to develop alternative refrigerant
gases that will not harm the ozone layer.
See also Electric refrigerator; Electric refrigerator; Food freezing;
Microwave cooking.
Further Reading
Refrigerant gas / 633
Leslie, Stuart W. Boss Kettering. New York: Columbia University
Press, 1983.
Mahoney, Thomas A. “The Seventy-one-year Saga of CFC’s.” Air
Conditioning, Heating and Refrigeration News (March 15, 1999).
Preville, Cherie R., and Chris King. “Cooling Takes Off in the Roaring
Twenties.” Air Conditioning, Heating and Refrigeration News
(April 30, 2001).

634
Reserpine
Reserpine
The invention: A drug with unique hypertension-decreasing effects
that provides clinical medicine with a versatile and effective
tool.
The people behind the invention:
Robert Wallace Wilkins (1906- ), an American physician and
clinical researcher
Walter E. Judson (1916- ) , an American clinical researcher
Treating Hypertension
Excessively elevated blood pressure, clinically known as “hypertension,”
has long been recognized as a pervasive and serious human
malady. In a few cases, hypertension is recognized as an effect
brought about by particular pathologies (diseases or disorders). Often,
however, hypertension occurs as the result of unknown causes.
Despite the uncertainty about its origins, unattended hypertension
leads to potentially dramatic health problems, including increased
risk of kidney disease, heart disease, and stroke.
Recognizing the need to treat hypertension in a relatively straightforward
and effective way, Robert Wallace Wilkins, a clinical researcher
at Boston University’s School of Medicine and the head of
Massachusetts Memorial Hospital’s Hypertension Clinic, began to
experiment with reserpine in the early 1950’s. Initially, the samples
that were made available to Wilkins were crude and unpurified.
Eventually, however, a purified version was used.
Reserpine has a long and fascinating history of use—both clinically
and in folk medicine—in India. The source of reserpine is the
root of the shrub Rauwolfia serpentina, first mentioned in Western
medical literature in the 1500’s but virtually unknown, or at least
unaccepted, outside India until the mid-twentieth century. Crude
preparations of the shrub had been used for a variety of ailments in
India for centuries prior to its use in the West.
Wilkins’s work with the drug did not begin on an encouraging
note, because reserpine does not act rapidly—a fact that had been

noted in Indian medical literature. The standard observation in
Western pharmacotherapy, however, was that most drugs work
rapidly; if a week has elapsed without positive effects being shown
by a drug, the conventional Western wisdom is that it is unlikely
to work at all. Additionally, physicians and patients alike tend to
look for rapid improvement or at least positive indications. Reserpine
is deceptive in this temporal context, and Wilkins and his
coworkers were nearly deceived. In working with crude preparations
of Rauwolfia serpentina, they were becoming very pessimistic,
when a patient who had been treated for many consecutive
days began to show symptomatic relief. Nevertheless, only after
months of treatment did Wilkins become a believer in the drug’s
beneficial effects.
The Action of Reserpine
Reserpine / 635
When preparations of pure reserpine became available in 1952,
the drug did not at first appear to be the active ingredient in the
crude preparations. When patients’ heart rate and blood pressure
began to drop after weeks of treatment, however, the investigators
saw that reserpine was indeed responsible for the improvements.
Once reserpine’s activity began, Wilkins observed a number of
important and unique consequences. Both the crude preparations
and pure reserpine significantly reduced the two most meaningful
measures of blood pressure. These two measures are systolic blood
pressure and diastolic blood pressure. Systolic pressure represents
the peak of pressure produced in the arteries following a contraction
of the heart. Diastolic pressure is the low point that occurs
when the heart is resting. To lower the mean blood pressure in the
system significantly, both of these pressures must be reduced. The
administration of low doses of reserpine produced an average drop
in pressure of about 15 percent, a figure that was considered less
than dramatic but still highly significant. The complex phenomenon
of blood pressure is determined by a multitude of factors, including
the resistance of the arteries, the force of contraction of the
heart, and the heartbeat rate. In addition to lowering the blood pressure,
reserpine reduced the heartbeat rate by about 15 percent, providing
an important auxiliary action.

636 / Reserpine
In the early 1950’s, various therapeutic drugs were used to treat
hypertension. Wilkins recognized that reserpine’s major contribution
would be as a drug that could be used in combination with
drugs that were already in use. His studies established that reserpine,
combined with at least one of the drugs already in use, produced
an additive effect in lowering blood pressure. Indeed, at
times, the drug combinations produced a “synergistic effect,” which
means that the combination of drugs created an effect that was more
effective than the sum of the effects of the drugs when they were administered
alone. Wilkins also discovered that reserpine was most
effective when administered in low dosages. Increasing the dosage
did not increase the drug’s effect significantly, but it did increase the
likelihood of unwanted side effects. This fact meant that reserpine
was indeed most effective when administered in low dosages along
with other drugs.
Wilkins believed that reserpine’s most unique effects were not
those found directly in the cardiovascular system but those produced
indirectly by the brain. Hypertension is often accompanied
by neurotic anxiety, which is both a consequence of the justifiable
fears of future negative health changes brought on by
prolonged hypertension and contributory to the hypertension itself.
Wilkins’s patients invariably felt better mentally, were less
anxious, and were sedated, but in an unusual way. Reserpine
made patients drowsy but did not generally cause sleep, and if
sleep did occur, patients could be awakened easily. Such effects
are now recognized as characteristic of tranquilizing drugs, or
antipsychotics. In effect, Wilkins had discovered a new and important
category of drugs: tranquilizers.
Impact
Reserpine holds a vital position in the historical development of
antihypertensive drugs for two reasons. First, it was the first drug
that was discovered to block activity in areas of the nervous system
that use norepinephrine or its close relative dopamine as transmitter
substances. Second, it was the first hypertension drug to be
widely accepted and used. Its unusual combination of characteristics
made it effective in most patients.

Since the 1950’s, medical science has rigorously examined cardiovascular
functioning and diseases such as hypertension. Many
new factors, such as diet and stress, have been recognized as factors
in hypertension. Controlling diet and life-style help tremendously
in treating hypertension, but if the nervous system could not be partially
controlled, many cases of hypertension would continue to be
problematic. Reserpine has made that control possible.
See also Abortion pill; Antibacterial drugs; Artificial kidney;
Birth control pill; Salvarsan.
Further Reading
Reserpine / 637
MacGregor, G. A., and Norman M. Kaplan. Hypertension. 2ded.
Abingdon: Health Press, 2001.
“Reconsidering Reserpine.” American Family Physician 45 (March,
1992).
Weber, Michael A. Hypertension Medicine. Totowa, N.J.: Humana,
2001.

638
Rice and wheat strains
Rice and wheat strains
The invention: Artificially created high-yielding wheat and rice
varieties that are helping food producers in developing countries
keep pace with population growth
The people behind the invention:
Orville A. Vogel (1907-1991), an agronomist who developed
high-yielding semidwarf winter wheats and equipment for
wheat research
Norman E. Borlaug (1914- ), a distinguished agricultural
scientist
Robert F. Chandler, Jr. (1907-1999), an international agricultural
consultant and director of the International Rice Research
Institute, 1959-1972
William S. Gaud (1907-1977), a lawyer and the administrator of
the U.S. Agency for International Development, 1966-1969
The Problem of Hunger
In the 1960’s, agricultural scientists created new, high-yielding
strains of rice and wheat designed to fight hunger in developing
countries. Although the introduction of these new grains raised levels
of food production in poor countries, population growth and
other factors limited the success of the so-called “Green Revolution.”
Before World War II, many countries of Asia, Africa, and Latin
America exported grain to Western Europe. After the war, however,
these countries began importing food, especially from the United
States. By 1960, they were importing about nineteen million tons of
grain a year; that level nearly doubled to thirty-six million tons in
1966. Rapidly growing populations forced the largest developing
countries—China, India, and Brazil in particular—to import huge
amounts of grain. Famine was averted on the Indian subcontinent
in 1966 and 1967 only by the United States shipping wheat to the region.
The United States then changed its food policy. Instead of contributing
food aid directly to hungry countries, the U.S. began

working to help such countries feed themselves.
The new rice and wheat strains were introduced just as countries
in Africa and Asia were gaining their independence from the European
nations that had colonized them. The Cold War was still going
strong, and Washington and other Western capitals feared that the
Soviet Union was gaining influence in the emerging countries. To
help counter this threat, the U.S. Agency for International Development
(USAID) was active in the Third World in the 1960’s, directing
or contributing to dozens of agricultural projects, including building
rural infrastructure (farm-to-market roads, irrigation projects,
and rural electric systems), introducing modern agricultural techniques,
and importing fertilizer or constructing fertilizer factories in
other countries. By raising the standard of living of impoverished
people in developing countries through applying technology to agriculture,
policymakers hoped to eliminate the socioeconomic conditions
that would support communism.
The Green Revolution
Rice and wheat strains / 639
It was against this background that William S. Gaud, administrator
of USAID from 1966 to 1969, first talked about a “green revolution”
in a 1968 speech before the Society for International Development
in Washington, D.C. The term “green revolution” has
been used to refer to both the scientific development of highyielding
food crops and the broader socioeconomic changes in a
country’s agricultural sector stemming from farmers’ adoption of
these crops.
In 1947, S. C. Salmon, a United States Department of Agriculture
(USDA) scientist, brought a wheat-dwarfing gene to the United
States. Developed in Japan, the gene produced wheat on a short
stalk that was strong enough to bear a heavy head of grain. Orville
Vogel, another USDA scientist, then introduced the gene into local
wheat strains, creating a successful dwarf variety known as Gaines
wheat. Under irrigation, Gaines wheat produced record yields. After
hearing about Vogel’s work, Norman Borlaug, who headed
the Rockefeller Foundation’s wheat-breeding program in Mexico,
adapted Gaines wheat, later called “miracle wheat,” to a variety of
growing conditions in Mexico.

640 / Rice and wheat strains
Workers in an Asian rice field. (PhotoDisc)
Success with the development of high-yielding wheat varieties
persuaded the Rockefeller and Ford foundations to pursue similar
ends in rice culture. The foundations funded the International Rice
Research Institute (IRRI) in Los Banos, Philippines, appointing as director
Robert F. Chandler, Jr., an international agricultural consultant.
Under his leadership, IRRI researchers cross-bred Peta, a tall variety
of rice from Indonesia, with Deo-geo-woo-gen, a dwarf rice from Taiwan,
to produce a new strain, IR-8. Released in 1966 and dubbed
“miracle rice,” IR-8 produced yields double those of other Asian rice
varieties and in a shorter time, 120 days in contrast to 150 to 180 days.
Statistics from India illustrate the expansion of the new grain varieties.
During the 1966-1967 growing season, Indian farmers planted
improved rice strains on 900,000 hectares, or 2.5 percent of the total
area planted in rice. By 1984-1985, the surface area planted in improved
rice varieties stood at 23.4 million hectares, or 56.9 percent of
the total. The rate of adoption was even faster for wheat. In 1966-
1967, improved varieties covered 500,000 hectares, comprising 4.2
percent of the total wheat crop. By the 1984-1985 growing season,
the surface area had expanded to 19.6 million hectares, or 82.9 percent
of the total wheat crop.

To produce such high yields, IR-8 and other genetically engineered
varieties of rice and wheat required the use of irrigation, fertilizers,
and pesticides. Irrigation further increased food production
by allowing year-round farming and the planting of multiple crops
on the same plot of land, either two crops of high-yielding grain varieties
or one grain crop and another food crop.
Expectations
Rice and wheat strains / 641
The rationale behind the introduction of high-yielding grains in
developing countries was that it would start a cycle of improvement
in the lives of the rural poor. High-yielding grains would lead to
bigger harvests and better-nourished and healthier families. If better
nutrition enabled more children to survive, the need to have large
families to ensure care for elderly parents would ease. A higher survival
rate of children would lead couples to use family planning,
slowing overall population growth and allowing per capita food intake
to rise.
The greatest impact of the Green Revolution has been seen in
Asia, which experienced dramatic increases in rice production, and
on the Indian subcontinent, with increases in rice and wheat yields.
Latin America, especially Mexico, enjoyed increases in wheat harvests.
Subsaharan Africa initially was left out of the revolution, as
scientists paid scant attention to increasing the yields of such staple
food crops as yams, cassava, millet, and sorghum. By the 1980’s,
however, this situation was being remedied with new research directed
toward millet and sorghum.
Research is conducted by a network of international agricultural
research centers. Backed by both public and private funds, these
centers cooperate with international assistance agencies, private
foundations, universities, multinational corporations, and government
agencies to pursue and disseminate research into improved
crop varieties to farmers in the Third World. IRRI and the International
Maize and Wheat Improvement Center (IMMYT) in Mexico
City are two of these agencies.

642 / Rice and wheat strains
Impact
Expectations went unrealized in the first few decades following
the green revolution. Despite the higher yields from millions of
tons of improved grain seeds imported into the developing world,
lower-yielding grains still accounted for much of the surface area
planted in grain. The reasons for this explain the limits and impact
of the Green Revolution.
The subsistence mentality dies hard. The main targets of Green
Revolution programs were small farmers, people whose crops provide
barely enough to feed their families and provide seed for the
next crop. If an experimental grain failed, they faced starvation.
Such farmers hedged their bets when faced with a new proposition,
for example, by intercropping, alternating rows of different grains
in the same field. In this way, even if one crop failed, another might
feed the family.
Poor farmers in developing countries also were likely to be illiterate
and not eager to try something they did not fully understand.
Also, by definition, poor farmers often did not have the means to
purchase the inputs—irrigation, fertilizer, and pesticides—required
to grow the improved varieties.
In many developing countries, therefore, rich farmers tended to be
the innovators. More likely than poor farmers to be literate, they also
had the money to exploit fully the improved grain varieties. They
also were more likely than subsistence-level farmers to be in touch
with the monetary economy, making purchases from the agricultural
supply industry and arranging sales through established marketing
channels, rather than producing primarily for personal or family use.
Once wealthy farmers adopted the new grains, it often became
more difficult for poor farmers to do so. Increased demand for limited
supplies, such as pesticides and fertilizers, raised costs, while
bigger-than-usual harvests depressed market prices. With high sales
volumes, owners of large farms could withstand the higher costs and
lower-per-unit profits, but smaller farmers often could not.
Often, the result of adopting improved grains was that small
farmers could no longer make ends meet solely by farming. Instead,
they were forced to hire themselves out as laborers on large farms.
Surges of laborers into a limited market depressed rural wages,

making it even more difficult for small farmers to eke out a living.
The result was that rich farmers got richer and poor farmers got
poorer. Often, small farmers who could no longer support their
families would leave rural areas and migrate to the cities, seeking
work and swelling the ranks of the urban poor.
Mixed Results
Orville A. Vogel
Rice and wheat strains / 643
Born in 1907, Orville Vogel grew up on a farm in eastern Nebraska,
and farming remained his passion for his entire life. He
earned bachelor’s and master’s degrees in agriculture from the
University of Nebraska, and then a doctorate in agronomy from
Washington State University (WSU) in 1939.
Eastern Washington agreed with him, and he stayed there.
He began his career as a wheat breeder 1931 for the U.S. Department
of Agriculture, stationed at WSU. During the next fortytwo
years, he also took on the responsibilities of associate
agronomist for the university’s Division of Agronomy and from
1960 until his retirement in 1973 was professor of agronomy.
At heart Vogel was an experimenter and tinkerer, renowned
among his peers for his keen powers of observation and his unselfishness.
In addition to the wheat strains he bred that helped
launch the Green Revolution, he took part in the search for
plant varieties resistant to snow mold and foot rot. However,
according to the father of the Green Revolution, Nobel laureate
Norman Borlaug, Vogel’s greatest contribution may not have
been semi-dwarf wheat varieties but the many innovations in
farming equipment he built as a sideline. These unheralded inventions
automated the planting and harvesting of research
plots, and so made research much easier to carry out and faster.
In recognition of his achievements, Vogel received the U.S.
National Medal of Science in 1975 and entered the Agricultural
Research Service’s Science Hall of Fame in 1987. Vogel died in
Washington in 1991.
The effects of the Green Revolution were thus mixed. The dissemination
of improved grain varieties unquestionably increased
grain harvests in some of the poorest countries of the world. Seed

644 / Rice and wheat strains
companies developed, produced, and sold commercial quantities of
improved grains, and fertilizer and pesticide manufacturers logged
sales to developing countries thanks to USAID-sponsored projects.
Along with disrupting the rural social structure and encouraging
rural flight to the cities, the Green Revolution has had other negative
effects. For example, the millions of tube wells sunk in India to
irrigate crops reduced groundwater levels in some regions faster
than they could be recharged. In other areas, excessive use of pesticides
created health hazards, and fertilizer use led to streams and
ponds being clogged by weeds. The scientific community became
concerned that the use of improved varieties of grain, many of
which were developed from the same mother variety, reduced the
genetic diversity of the world’s food crops, making them especially
vulnerable to attack by disease or pests.
Perhaps the most significant impact of the Green Revolution is
the change it wrought in the income and class structure of rural areas;
often, malnutrition was not eliminated in either the countryside
or the cities. Almost without exception, the relative position of peasants
deteriorated. Many analysts admit that the Green Revolution
did not end world hunger, but they argue that it did buy time. The
poorest of the poor would be even worse off without it.
See also Artificial chromosome; Cloning; Genetic “fingerprinting”;
Genetically engineered insulin; In vitro plant culture.
Further Reading
Glaeser, Bernhard, ed. The Green Revolution Revisited: Critique and Alternatives.
London: Allen & Unwin, 1987.
Hayami, Yujiro, and Masao Kikuchi. A Rice Village Saga: Three Decades
of Green Revolution in the Philippines. Lanham, Md.: Barnes
and Noble, 2000.
Karim, M. Bazlul. The Green Revolution: An International Bibliography.
New York: Greenwood Press, 1986.
Lipton, Michael, and Richard Longhurst. New Seeds and Poor People.
Baltimore: Johns Hopkins University Press, 1989.
Perkins, John H. Geopolitics and the Green Revolution: Wheat, Genes,
and the Cold War. New York: Oxford University Press, 1997.

Richter scale
Richter scale
The invention: A scale for measuring the strength of earthquakes
based on their seismograph recordings.
The people behind the invention:
Charles F. Richter (1900-1985), an American seismologist
Beno Gutenberg (1889-1960), a German American seismologist
Kiyoo Wadati (1902- ), a pioneering Japanese seismologist
Giuseppe Mercalli (1850-1914), an Italian physicist,
volcanologist, and meteorologist
Earthquake Study by Eyewitness Report
645
Earthquakes range in strength from barely detectable tremors to
catastrophes that devastate large regions and take hundreds of thousands
of lives. Yet the human impact of earthquakes is not an accurate
measure of their power; minor earthquakes in heavily populated regions
may cause great destruction, whereas powerful earthquakes in
remote areas may go unnoticed. To study earthquakes, it is essential
to have an accurate means of measuring their power.
The first attempt to measure the power of earthquakes was the
development of intensity scales, which relied on damage effects
and reports by witnesses to measure the force of vibration. The
first such scale was devised by geologists Michele Stefano de Rossi
and François-Alphonse Forel in 1883. It ranked earthquakes on a
scale of 1 to 10. The de Rossi-Forel scale proved to have two serious
limitations: Its level 10 encompassed a great range of effects, and its
description of effects on human-made and natural objects was so specifically
European that it was difficult to apply the scale elsewhere.
To remedy these problems, Giuseppe Mercalli published a revised
intensity scale in 1902. The Mercalli scale, as it came to be
called, added two levels to the high end of the de Rossi-Forel scale,
making its highest level 12. It also was rewritten to make it more
globally applicable. With later modifications by Charles F. Richter,
the Mercalli scale is still in use.
Intensity measurements, even though they are somewhat subjec-

646 / Richter scale
Charles F. Richter
Charles Francis Richter was born in Ohio in 1900. After his
mother divorced his father, she moved the family to Los Angles
in 1909. A precocious student, Richter entered the University of
Southern California at sixteen and transferred to Stanford University
a year later, majoring in physics. He graduated in 1920
and finished a doctorate in theoretical physics at the California
Institute of Technology in 1928.
While Richter was a graduate student at Caltech, Noble laureate
Robert A. Millikan lured him away from his original interest,
astronomy, to become an assistant at the seismology laboratory.
Richter realized that seismology was then a relatively new
discipline and that he could help it mature. He stayed with it—
and Caltech—for the rest of his university career, retiring as
professor emeritus in 1970. In 1971 he opened a consulting
firm—Lindvall, Richter and Associates—to assess the earthquake
readiness of structures.
Richter published more than two hundred articles about
earthquakes and earthquake engineering and two influential
books, Elementary Seismology and Seismicity of the Earth (with
Beno Gutenberg). These works, together with his teaching,
trained a generation of earthquake researchers and gave them a
basic tool, the Richter scale, to work with. He died in California
in 1985.
tive, are very useful in mapping the extent of earthquake effects.
Nevertheless, intensity measurements are still not ideal measuring
techniques. Intensity varies from place to place and is strongly influenced
by geologic features, and different observers frequently report
different intensities. There is a need for an objective method of
describing the strength of earthquakes with a single measurement.
Measuring Earthquakes One Hundred Kilometers Away
An objective technique for determining the power of earthquakes
was devised in the early 1930’s by Richter at the California Institute
of Technology in Pasadena, California. The eventual usefulness of
the scale that came to be called the “Richter scale” was completely
unforeseen at first.

Amplified Maximum Ground Motion (Microns)
9
10
8
10
Richter scale / 647
Alaska, 1964
San Francisco, 1906
Great devastation;
many fatalities possible
In 1931, the California Institute of Technology was preparing to
issue a catalog of all earthquakes detected by its seismographs in the
preceding three years. Several hundred earthquakes were listed,
most of which had not been felt by humans, but detected only by instruments.
Richter was concerned about the possible misinterpretations
of the listing. With no indication of the strength of the earthquakes,
the public might overestimate the risk of earthquakes in
areas where seismographs were numerous and underestimate the
risk in areas where seismographs were few.
To remedy the lack of a measuring method, Richter devised the
scale that now bears his name. On this scale, earthquake force is expressed
in magnitudes, which in turn are expressed in whole numbers
and decimals. Each increase of one magnitude indicates a tenfold jump
in the earthquake’s force. These measurements were defined for a
standard seismograph located one hundred kilometers from the earthquake.
By comparing records for earthquakes recorded on different
8
8.9
Great
Major
New Madrid, Missouri, 1812
7
10
7
6 10
5
10
4
10
2
10
1
10 -1 0
3
1
2
Not felt
Strong
6
Moderate
5
4 Small
Minor
Damage begins;
fatalities rare
-1 0 1 2 3 4 5 6 7 8 9
Magnitude
Graphic representation of the Richter scale showing examples of historically important
earthquakes.

648 / Richter scale
devices at different distances, Richter was able to create conversion tables
for measuring magnitudes for any instrument at any distance.
Impact
Richter had hoped to create a rough means of separating small,
medium, and large earthquakes, but he found that the scale was capable
of making much finer distinctions. Most magnitude estimates
made with a variety of instruments at various distances from earthquakes
agreed to within a few tenths of a magnitude. Richter formally
published a description of his scale in January, 1935, in the
Bulletin of the Seismological Society of America. Other systems of estimating
magnitude had been attempted, notably that of Kiyoo Wadati,
published in 1931, but Richter’s system proved to be the most workable
scale yet devised and rapidly became the standard.
Over the next few years, the scale was refined. One critical refinement
was in the way seismic recordings were converted into magnitude.
Earthquakes produce many types of waves, but it was not
known which type should be the standard for magnitude. So-called
surface waves travel along the surface of the earth. It is these waves
that produce most of the damage in large earthquakes; therefore, it
seemed logical to let these waves be the standard. Earthquakes deep
within the earth, however, produce few surface waves. Magnitudes
based on surface waves would therefore be too small for these earthquakes.
Deep earthquakes produce mostly waves that travel through
the solid body of the earth; these are the so-called body waves.
It became apparent that two scales were needed: one based on
surface waves and one on body waves. Richter and his colleague
Beno Gutenberg developed scales for the two different types of
waves, which are still in use. Magnitudes estimated from surface
waves are symbolized by a capital M, and those based on body
waves are denoted by a lowercase m.
From a knowledge of Earth movements associated with seismic
waves, Richter and Gutenberg succeeded in defining the energy
output of an earthquake in measurements of magnitude. A magnitude
6 earthquake releases about as much energy as a one-megaton
nuclear explosion; a magnitude 0 earthquake releases about as
much energy as a small car dropped off a two-story building.

See also Carbon dating; Geiger counter; Gyrocompass; Sonar;
Scanning tunneling microscope.
Further Reading
Richter scale / 649
Bates, Charles C., Thomas Frohock Gaskell, and Robert B. Rice. Geophysics
in the Affairs of Man: A Personalized History of Exploration
Geophysics and Its Allied Sciences of Seismology and Oceanography.
New York: Pergamon Press, 1982.
Davison, Charles. 1927. Reprint. The Founders of Seismology. New
York: Arno Press, 1978.
Howell, Benjamin F. An Introduction to Seismological Research: History
and Development. Cambridge, N.Y.: Cambridge University Press,
1990.

650
Robot (household)
Robot (household)
The invention: The first available personal robot, Hero 1 could
speak; carry small objects in a gripping arm, and sense light, motion,
sound, and time.
The people behind the invention:
Karel Capek (1890-1938), a Czech playwright
The Health Company, an American electronics manufacturer
Personal Robots
In 1920, the Czech playwright Karel Capek introduced the term
robot, which he used to refer to intelligent, humanoid automatons
that were subservient to humans. Robots such as those described
by Capek have not yet been developed; their closest counterparts
are the nonintelligent automatons used by industry and by private
individuals. Most industrial robots are heavy-duty, immobile machines
designed to replace humans in routine, undesirable, monotonous
jobs. Most often, they use programmed gripping arms to
carry out tasks such as spray painting cars, assembling watches,
and shearing sheep.
Modern personal robots are smaller, more mobile, less expensive
models that serve mostly as toys or teaching tools. In some
cases, they can be programmed to carry out activities such as walking
dogs or serving mixed drinks. Usually, however, it takes more
effort to program a robot to perform such activities than it does to
do them oneself.
The Hero 1, which was first manufactured by the Heath Company
in 1982, has been a very popular personal robot. Conceived
as a toy and a teaching tool, the Hero 1 can be programmed
to speak; to sense light, sound, motion, and time; and
to carry small objects. The Hero 1 and other personal robots are
often viewed as tools that will someday make it possible to produce
intelligent robots.

Hero 1 Operation
Robot (household) / 651
The concept of artificial beings serving humanity has existed
since antiquity (for example, it is found in Greek mythology). Such
devices, which are now called robots, were first actualized, in a
simple form, in the 1960’s. Then, in the mid-1970’s, the manufacture
of personal robots began. One of the first personal robots was
the Turtle, which was made by the Terrapin Company of Cambridge,
Massachusetts. The Turtle was a toy that entertained owners
via remote control, programmable motion, a beeper, and blinking
displays. The Turtle was controlled by a computer to which it
was linked by a cable.
Among the first significant personal robots was the Hero 1. This
robot, which was usually sold in the form of a $1,000 kit that had to
be assembled, is a squat, thirty-nine-pound mobile unit containing a
head, a body, and a base. The head contains control boards, sensors,
and a manipulator arm. The body houses control boards and related
electronics, while the base contains a three-wheel-drive unit that
renders the robot mobile.
The Heath Company, which produced the Hero 1, viewed it as
providing entertainment for and teaching people who are interested
in robot applications. To facilitate these uses, the following
abilities were incorporated into the Hero 1: independent operation
via rechargeable batteries; motion- and distance/position-sensing
capability; light, sound, and language use/recognition; a manipulator
arm to carry out simple tasks; and easy programmability.
The Hero 1 is powered by four rechargeable batteries arranged as
two 12-volt power supplies. Recharging is accomplished by means
of a recharging box that is plugged into a home outlet. It takes six to
eight hours to recharge depleted batteries, and complete charging is
signaled by an indicator light. In the functioning robot, the power
supplies provide 5-volt and 12-volt outputs to logic and motor circuits,
respectively.
The Hero 1 moves by means of a drive mechanism in its base. The
mechanism contains three wheels, two of which are unpowered
drones. The third wheel, which is powered for forward and reverse
motion, is connected to a stepper motor that makes possible directional
steering. Also included in the powered wheel is a metal disk

652 / Robot (household)
with spaced reflective slots that helps Hero 1 to identify its position.
As the robot moves, light is used to count the slots, and the slot
count is used to measure the distance the robot has traveled, and
therefore its position.
The robot’s “senses,” located in its head, consist of sound, light,
and motion detectors as well as a phoneme synthesizer (phonemes
are sounds, or units of speech). All these components are connected
with the computer. The Hero 1 can detect sounds between 200 and
5,000 hertz. Its motion sensor detects all movement within a 15-foot
radius. The phoneme synthesizer is capable of producing most
words by using combinations of 64 phonemes. In addition, the robot
keeps track of time by using an internal clock/calendar.
The Hero 1 can carry out various tasks by using a gripper that
serves as a hand. The arm on which the gripper is located is connected
to the back of the robot’s head. The head (and, therefore, the
arm) can rotate 350 degrees horizontally. In addition, the arm contains
a shoulder motor that allows it to rise or drop 150 degrees vertically,
and its forearm can be either extended or retracted. Finally, a
wrist motor allows the gripper’s tip to rotate by 350 degrees, and the
two-fingered gripper can open up to a maximum width of 3.5
inches. The arm is not useful except as an educational tool, since its
load-bearing capacity is only about a pound and its gripper can exert
a force of only 6 ounces.
The computational capabilities of the robot are much more impressive
than its physical capabilities. Programming is accomplished
by means of a simple keypad located on the robot’s head, which
provides an inexpensive, easy-to-use method of operator-computer
communication. To make things simpler for users who want entertainment
without having to learn robotics, a manual mode is included
for programming. In the manual mode, a hand-held teaching
pendant is connected to Hero 1 and used to program all the
motion capabilities of the robot. The programming of sensory and
language abilities, however, must be accomplished by using the
keyboard. Using the keyboard and the various options that are
available enables Hero 1 owners to program the robot to perform
many interesting activities.

Consequences
The Hero 1 had a huge impact on robotics; thousands of people
purchased it and used it for entertainment, study, and robot design.
The Heath Company itself learned from the Hero 1 and later introduced
an improved version: Heathkit 2000. This personal robot,
which costs between $2,000 and $4,500, has ten times the capabilities
of Hero 1, operates via radio-controlled keyboard, contains a
voice synthesizer that can be programmed in any language, and
plugs itself in for recharging.
Other companies, including the Androbot Company in California,
have manufactured personal robots that sell for up to $10,000.
One such robot is the Androbot BOB (brains on board). It can guard
a home, call the police, walk at 2.5 kilometers per hour, and sing.
Androbot has also designed Topo, a personal robot that can serve
drinks. Still other robots can sort laundry and/or vacuum-clean
houses. Although modern robots lack intelligence and merely have
the ability to move when they are directed to by a program or by remote
control, there is no doubt that intelligent robots will be developed
in the future.
See also Electric refrigerator; Microwave cooking; Robot (industrial);
Vacuum cleaner; Washing machine.
Further Reading
Robot (household) / 653
Aleksander, Igor, and Piers Burnett. Reinventing Man: The Robot Becomes
Reality. London: Kogan Page, 1983.
Asimov, Isaac. Robots: Machines in Man’s Image. New York: Harmony
Books, 1985.
Bell, Trudy E. “Robots in the Home: Promises, Promises.” IEEE Spectrum
22, no. 5 (May, 1985).
Whalen, Bernie. “Upscale Consumers Adopt Home Robots, but
Widespread Lifestyle Impact Is Years Away.” Marketing News 17,
no. 24 (November 25, 1983).

654
Robot (industrial)
Robot (industrial)
The invention: The first industrial robots, Unimates were designed to
replace humans in undesirable, hazardous, and monotonous jobs.
The people behind the invention:
Karel Capek (1890-1938), a Czech playwright
George C. Devol, Jr. (1912- ), an American inventor
Joseph F. Engelberger (1925- ), an American entrepreneur
Robots, from Concept to Reality
The 1920 play Rossum’s Universal Robots, by Czech writer Karel
Capek, introduced robots to the world. Capek’s humanoid robots—
robot, a word created by Capek, essentially means slave—revolted
and took over the world, which made the concept of robots somewhat
frightening. The development of robots, which are now defined
as machines that do work that would ordinarily be carried out
by humans, has not yet advanced to the stage of being able to produce
humanoid robots, however, much less robots capable of carrying
out a revolt.
Most modern robots are found in industry, where they perform
dangerous or monotonous tasks that previously were done by humans.
The first industrial robots were the Unimates (short for “universal
automaton”), which were derived from a robot design invented
by George C. Devol and patented in 1954. The first Unimate
prototypes, developed by Devol and Joseph F. Engelberger, were
completed in 1962 by Unimation Incorporated and tested in industry.
They were so successful that the company, located in Danbury,
Connecticut, manufactured and sold thousands of Unimates to
companies in the United States and abroad. Unimates are very versatile
at performing routine industrial tasks and are easy to program
and reprogram. The tasks they perform include various steps in automobile
manufacturing, spray painting, and running lathes. The
huge success of the Unimates led companies in other countries to
produce their own industrial robots, and advancing technology has
improved all industrial robots tremendously.

A New Industrial Revolution
Robot (industrial) / 655
Each of the first Unimate robots, which were priced at $25,000,
was almost five feet tall and stood on a four-foot by five-foot base. It
has often been said that a Unimate resembles the gun turret of a
minitank, set atop a rectangular box. In operation, such a robot will
swivel, swing, and/or dip and turn at the wrist of its hydraulically
powered arm, which has a steel hand. The precisely articulated
hand can pick up an egg without breaking it. At the same time, however,
it is powerful enough to lift a hundred-pound weight.
The Unimate is a robotic jack of all trades: It can be programmed,
in about an hour, to carry out a complex operation, after which it can
have its memory erased and be reprogrammed in another hour to
do something entirely different. In addition, programming a Unimate
requires no special training. The programmer simply uses a teachcable
selector that allows the programmer to move the Unimate arm
through the desired operation. This selector consists of a group of
pushbutton control boxes, each of which is equipped with buttons
in opposed pairs. Each button pair records the motion that will put a
Unimate arm through one of five possible motions, in opposite directions.
For example, pushing the correct buttons will record a motion
in which the robot’s arm moves out to one side, aims upward,
and angles appropriately to carry out the first portion of its intended
job. If the Unimate overshoots, undershoots, or otherwise
performs the function incorrectly, the activity can be fine-tuned
with the buttons.
Once the desired action has been performed correctly, pressing a
“record” button on the robot’s main control panel enters the operation
into its computer memory. In this fashion, Unimates can be programmed
to carry out complex actions that require as many as two
hundred commands. Each command tells the Unimate to move its
arm or hand in a given way by combining the following five motions:
sliding the arm forward, swinging the arm horizontally, tilting
the arm up or down, bending the wrist up or down, and swiveling
the hand in a half-circle clockwise or counterclockwise.
Before pressing the “record” button on the Unimate’s control
panel, the operator can also command the hand to grasp an item
when in a particular position. Furthermore, the strength of the

656 / Robot (industrial)
grasp can be controlled, as can the duration of time between each action.
Finally, the Unimate can be instructed to start or stop another
routine (such as operating a paint sprayer) at any point. Once the instructor
is satisfied with the robot’s performance, pressing a “repeat
continuous” control starts the Unimate working. The robot will stop
repeating its program only when it is turned off.
Inside the base of an original Unimate is a magnetic drum that
contains its memory. The drum turns intermittently, moving each of
two hundred long strips of metal beneath recording heads. This
strip movement brings specific portions of each strip—dictated by
particular motions—into position below the heads. When the “record”
button is pressed after a motion is completed, the hand position
is recorded as a series of numbers that tells the computer the
complete hand position in each of the five permissible movement
modes.
Once “repeat continuous” is pressed, the computer begins the
command series by turning the drum appropriately, carrying out
each memorized command in the chosen sequence. When the sequence
ends, the computer begins again, and the process repeats
until the robot is turned off. If a Unimate user wishes to change the
function of such a robot, its drum can be erased and reprogrammed.
Users can also remove programmed drums, store them for future
use, and replace them with new drums.
Consequences
The first Unimates had a huge impact on industrial manufacturing.
In time, different sizes of robots became available so that additional
tasks could be performed, and the robots’ circuitry was improved.
Because they have no eyes and cannot make judgments,
Unimates are limited to relatively simple tasks that are coordinated
by means of timed operations and simple computer interactions.
Most of the thousands of modern Unimates and their multinational
cousins in industry are very similar to the original Unimates
in terms of general capabilities, although they can now assemble
watches and perform other delicate tasks that the original Unimates
could not perform. The crude magnetic drums and computer controls
have given way to silicon chips and microcomputers, which

have made the robots more accurate and reliable. Some robots can
even build other robots, and others can perform tasks such as mowing
lawns and walking dogs.
Various improvements have been planned that will ultimately
lead to some very interesting and advanced modifications. It is
likely that highly sophisticated humanoid robots like those predicted
by Karel Capek will be produced at some future time. One
can only hope that these robots will not rebel against their human
creators.
See also CAD/CAM; Robot (household); SAINT; Virtual machine.
Further Reading
Robot (industrial) / 657
Aleksander, Igor, and Piers Burnett. Reinventing Man: The Robot Becomes
Reality. London: Kogan Page, 1983.
Asimov, Isaac. Robots: Machines in Man’s Image. New York: Harmony
Books, 1985.
Chakravarty, Subrata N. “Springtime for an Ugly Duckling.” Forbes
127, no. 9 (April, 1981).
Hartley, J. “Robots Attack the Quiet World of Arc Welding.” Engineer
246, no. 6376 (June, 1978).
Lamb, W. G. Unimates at Work. Edited by C. W. Burckhardt. Basel,
Switzerland: Birkhauser Verlag, 1975.
Tuttle, Howard C. “Robots’ Contribution: Faster Cycles, Better
Quality.” Production 88, no. 5 (November, 1981).

658
Rocket
Rocket
The invention: Liquid-fueled rockets developed by Robert H. Goddard
made possible all later developments in modern rocketry,
which in turn has made the exploration of space practical.
The person behind the invention:
Robert H. Goddard (1882-1945), an American physics professor
History in a Cabbage Patch
Just as the age of air travel began on an out-of-the-way shoreline
at Kitty Hawk, North Carolina, with the Wright brothers’ airplane
in 1903, so too the seemingly impossible dream of spaceflight
began in a cabbage patch in Auburn, Massachusetts, with
Robert H. Goddard’s launch of a liquid-fueled rocket on March 16,
1926. On that clear, cold day, with snow still on the ground, Goddard
launched a three-meter-long rocket using liquid oxygen and
gasoline. The flight lasted only about two and one-half seconds,
during which the rocket rose 12 meters and landed about 56 meters
away.
Although the launch was successful, the rocket’s design was
clumsy. At first, Goddard had thought that a rocket would be
steadier if the motor and nozzles were ahead of the fuel tanks,
rather like a horse and buggy. After this first launch, it was clear
that the motor needed to be placed at the rear of the rocket. Although
Goddard had spent several years working on different
pumps to control the flow of fuel to the motor, the first rocket had
no pumps or electrical system. Henry Sacks, a Clark University
machinist, launched the rocket by turning a valve, placing an alcohol
stove beneath the motor, and dashing for safety. Goddard and
his coworker Percy Roope watched the launch from behind an iron
wall.
Despite its humble setting, this simple event changed the course
of history. Many people saw in Goddard’s launch the possibilities
for high-altitude research, space travel, and modern weaponry. Although
Goddard invented and experimented mostly in private,

others in the United States, the Soviet Union, and Germany quickly
followed in his footsteps. The V-2 rockets used by Nazi Germany
in World War II (1939-1945) included many of Goddard’s designs
and ideas.
A Lifelong Interest
Rocket / 659
Goddard’s success was no accident. He had first become interested
in rockets and space travel when he was seventeen, no doubt
because of reading books such as H. G. Wells’s The War of the Worlds
(1898) and Garrett P. Serviss’s Edison’s Conquest of Mars (1898). In
1907, he sent to several scientific journals a paper describing his ideas
about traveling through a near vacuum. Although the essay was rejected,
Goddard began thinking about liquid fuels in 1909. After finishing
his doctorate in physics at Clark University and postdoctoral
studies at Princeton University, he began to experiment.
One of the things that made Goddard so successful was his ability
to combine things he had learned from chemistry, physics, and
engineering into rocket design. More than anyone else at the time,
Goddard had the ability to combine ideas with practice.
Goddard was convinced that the key for moving about in space
was the English physicist and mathematician Sir Isaac Newton’s
third law of motion (for every action there is an equal and opposite
reaction). To prove this, he showed that a gun recoiled when it was
fired in a vacuum. During World War I (1914-1918), Goddard
moved to the Mount Wilson Observatory in California, where he
investigated the use of black powder and smokeless powder as
rocket fuel. Goddard’s work led to the invention of the bazooka, a
weapon that was much used during World War II, as well as bombardment
and antiaircraft rockets.
After World War I, Goddard returned to Clark University. By
1920, mostly because of the experiments he had done during the
war, he had decided that a liquid-fuel motor, with its smooth thrust,
had the best chance of boosting a rocket into space. The most powerful
fuel was hydrogen, but it is very difficult to handle. Oxygen had
many advantages, but it was hard to find and extremely dangerous,
since it boils at −148 degrees Celsius and explodes when it comes in
contact with oils, greases, and flames. Other possible fuels were pro-

(Library of Congress)
660 / Rocket
Robert H. Goddard
In 1920 The New York Times made fun of Robert Hutchings
Goddard (1882-1945) for claiming that rockets could travel
through outer space to the Moon. It was impossible, the newspaper’s
editorial writer confidently asserted, because in outer
space the engine would have no air to push against and so
could not move the rocket. A sensitive, quiet man, the Clark
University physics professor was stung by the public rebuke,
all the more so because it displayed ignorance of
basic physics. “Every vision is a joke,” Goddard
said, somewhat bitterly, “until the first man accomplishes
it.”
Goddard had already proved that a rocket could
move in a vacuum, but he refrained from rebutting
the Times article. In 1919 he had become the first
American to describe mathematically the theory of
rocket propulsion in his classic article “A Method of
Reaching Extreme Altitude,” and during World War I
he had acquired experience designing solid-fuel rockets.
However, even though he was the world’s leading
expert on rocketry, he decided to seek privacy for
his experiments. His successful launch of a liquidfuel
rocket in 1926, followed by new designs that reached ever
higher altitudes, was a source of satisfaction, as were his 214
patents, but real recognition of his achievements did not come
his way until World War II. In 1942 he was named director of research
at the U.S. Navy’s Bureau of Aeronautics, for which he
worked on jet-assisted takeoff rockets and variable-thrust liquid-propellant
rockets. In 1943 the Curtiss-Wright Corporation
hired him as a consulting engineer, and in 1945 he became director
of the American Rocket Society.
The New York Times finally apologized to Goddard for its
1920 article on the morning after Apollo 11 took off for the
Moon in 1969. However, Goddard, who battled tuberculosis
most of his life, had died twenty-four years earlier.
pane, ether, kerosene, or gasoline, but they all had serious disadvantages.
Finally, Goddard found a local source of oxygen and was able
to begin testing its thrust.

Another problem was designing a fuel pump. Goddard and his
assistant Nils Riffolt spent years on this problem before the historic
test flight of March, 1926. In the end, because of pressure from the
Smithsonian Institution and others who were funding his research,
Goddard decided to do without a pump and use an inert gas to
push the fuel into the explosion chamber.
Goddard worked without much funding between 1920 and 1925.
Riffolt helped him greatly in designing a pump, and Goddard’s
wife, Esther, photographed some of the tests and helped in other
ways. Clark University had granted him some research money in
1923, but by 1925 money was in short supply, and the Smithsonian
Institution did not seem willing to grant more. Goddard was convinced
that his research would be taken seriously if he could show
some serious results, so on March 16, 1926, he launched a rocket
even though his design was not yet perfect. The success of that
launch not only changed his career but also set the stage for rocketry
experiments both in the United States and in Europe.
Impact
Rocket / 661
Goddard was described as being secretive and a loner. He never
tried to cash in on his invention but continued his research during
the next three years. On July 17, 1929, Goddard launched a rocket
carrying a camera and instruments for measuring temperature
and air pressure. The New York Times published a story about the
noisy crash of this rocket and local officials’ concerns about public
safety. The article also mentioned Goddard’s idea that a similar
rocket might someday strike the Moon. When American aviation
hero Charles A. Lindbergh learned of Goddard’s work, Lindbergh
helped him to get grants from the Carnegie Institution and the
Guggenheim Foundation.
By the middle of 1930, Goddard and a small group of assistants
had established a full-time research program near Roswell, New
Mexico. Now that money was not so much of a problem, Goddard
began to make significant advances in almost every area of astronautics.
In 1941, Goddard launched a rocket to a height of 2,700 meters.
Flight stability was helped by a gyroscope, and he was finally
able to use a fuel pump.

662 / Rocket
During the 1920’s and 1930’s, members of the American Rocket
Society and the German Society for Space Travel continued their
own research. When World War II began, rocket research became a
high priority for the American and German governments.
Germany’s success with the V-2 rocket was a direct result of
Goddard’s research and inventions, but the United States did not
benefit fully from Goddard’s work until after his death. Nevertheless,
Goddard remains modern rocketry’s foremost pioneer—a scientist
with vision, understanding, and practical skill.
See also Airplane; Artificial satellite; Communications satellite;
Cruise missile; Hydrogen bomb; Stealth aircraft; Supersonic passenger
plane; Turbojet; V-2 rocket; Weather satellite.
Further Reading
Alway, Peter. Retro Rockets: Experimental Rockets, 1926-1941. Ann Arbor,
Mich.: Saturn Press, 1996.
Goddard, Robert Hutchings. The Autobiography of Robert Hutchings
Goddard, Father of the Space Age: Early Years to 1927. Worcester,
Mass.: A. J. St. Onge, 1966.
Lehman, Milton. Robert H. Goddard: Pioneer of Space Research. New
York: Da Capo Press, 1988.

Rotary dial telephone
Rotary dial telephone
The invention: The first device allowing callers to connect their
telephones to other parties without the aid of an operator, the rotary
dial telephone preceded the touch-tone phone.
The people behind the invention:
Alexander Graham Bell (1847-1922), an American inventor
Antoine Barnay (1883-1945), a French engineer
Elisha Gray (1835-1901), an American inventor
Rotary Telephones Dials Make Phone Linkups Automatic
663
The telephone uses electricity to carry sound messages over long
distances. When a call is made from a telephone set, the caller
speaks into a telephone transmitter and the resultant sound waves
are converted into electrical signals. The electrical signals are then
transported over a telephone line to the receiver of a second telephone
set that was designated when the call was initiated. This receiver
reverses the process, converting the electrical signals into the
sounds heard by the recipient of the call. The process continues as
the parties talk to each other.
The telephone was invented in the 1870’s and patented in 1876 by
Alexander Graham Bell. Bell’s patent application barely preceded
an application submitted by his competitor Elisha Gray. After a
heated patent battle between Bell and Gray, which Bell won, Bell
founded the Bell Telephone Company, which later came to be called
the American Telephone and Telegraph Company.
At first, the transmission of phone calls between callers and recipients
was carried out manually, by switchboard operators. In
1923, however, automation began with Antoine Barnay’s development
of the rotary telephone dial. This dial caused the emission of
variable electrical impulses that could be decoded automatically
and used to link the telephone sets of callers and call recipients. In
time, the rotary dial system gave way to push-button dialing and
other more modern networking techniques.

664 / Rotary dial telephone
Rotary-dial telephone. (Image Club Graphics)
Telephones, Switchboards, and Automation
The carbon transmitter, which is still used in many modern telephone
sets, was the key to the development of the telephone by Alexander
Graham Bell. This type of transmitter—and its more modern
replacements—operates like an electric version of the human
ear. When a person talks into the telephone set in a carbon transmitter-equipped
telephone, the sound waves that are produced strike
an electrically connected metal diaphragm and cause it to vibrate.
The speed of vibration of this electric eardrum varies in accordance
with the changes in air pressure caused by the changing tones of the
speaker’s voice.
Behind the diaphragm of a carbon transmitter is a cup filled with
powdered carbon. As the vibrations cause the diaphragm to press
against the carbon, the electrical signals—electrical currents of varying
strength—pass out of the instrument through a telephone wire.
Once the electrical signals reach the receiver of the phone being
called, they activate electromagnets in the receiver that make a second
diaphragm vibrate. This vibration converts the electrical signals
into sounds that are very similar to the sounds made by the person
who is speaking. Therefore, a telephone receiver may be viewed
as an electric mouth.
In modern telephone systems, transportation of the electrical signals
between any two phone sets requires the passage of those signals
through vast telephone networks consisting of huge numbers
of wires, radio systems, and other media. The linkup of any two

Alexander Graham Bell
Rotary dial telephone / 665
During the funeral for Alexander Graham Bell in 1922, telephone
service throughout the United States stopped for one
minute to honor him. To most people he was the inventor of the
telephone. In fact, his genius ranged much further.
Bell was born in Edinburgh, Scotland, in 1847. His father,
an elocutionist who invented a phonetic alphabet, and his
mother, who was deaf, imbued him with deep curiosity, especially
about sound. As a boy Bell became an exceptional pianist,
and he produced his first invention, for cleaning wheat, at
fourteen. After Edinburgh’s Royal High School, he attended
classes at Edinburgh University and University College, London,
but at the age of twenty-three, battling tuberculosis, he
left school to move with his parents to Ontario, Canada, to
convalesce. Meanwhile, he worked on his idea for a telegraph
capable of sending multiple messages at once. From it grew
the basic concept for the telephone. He developed it while
teaching Visible Speech at the Boston School for Deaf Mutes
after 1871. Assisted by Thomas Watson, he succeeded in sending
speech over a wire and was issued a patent for his device,
among the most valuable ever granted, in 1876. His demonstration
of the telephone later that year at Philadelphia’s
Centennial Exhibition and its subsequent development into a
household appliance brought him wealth and fame.
He moved to Nova Scotia, Canada, and continued inventing.
He created a photophone, tetrahedron modules for construction,
and an airplane, the Silver Dart, which flew in 1909.
Even though existing technology made them impracticable,
some of his ideas anticipated computers and magnetic sound
recording. His last patented invention, tested three years before
his death, was a hydrofoil. Capable of reaching seventy-one
miles per hour and freighting fourteen thousand pounds, the
HD-4 was then the fastest watercraft in the world.
Bell also helped found the National Geographic Society in
1888 and became its president in 1898. He hired Gilbert Grosvenor
to edit the society’s famous magazine, National Geographic
and together they planned the format—breathtaking
photography and vivid writing—that made it one of the world’s
best known magazines.

666 / Rotary dial telephone
phone sets was originally, however, accomplished manually—on a
relatively small scale—by a switchboard operator who made the
necessary connections by hand. In such switchboard systems, each
telephone set in the network was associated with a jack connector in
the switchboard. The operator observed all incoming calls, identified
the phone sets for which they were intended, and then used
wires to connect the appropriate jacks. At the end of the call, the
jacks were disconnected.
This cumbersome methodology limited the size and efficiency of
telephone networks and invaded the privacy of callers. The development
of automated switching systems soon solved these problems
and made switchboard operators obsolete. It was here that
Antoine Barnay’s rotary dial was used, making possible an exchange
that automatically linked the phone sets of callers and call
recipients in the following way.
First, a caller lifted a telephone “off the hook,” causing a switchhook,
like those used in modern phones, to close the circuit that connected
the telephone set to the telephone network. Immediately, a
dial tone (still familiar to callers) came on to indicate that the automatic
switching system could handle the planned call. When the
phone dial was used, each number or letter that was dialed produced
a fixed number of clicks. Every click indicated that an electrical
pulse had been sent to the network’s automatic switching system,
causing switches to change position slightly. Immediately after
a complete telephone number was dialed, the overall operation of
the automatic switchers connected the two telephone sets. This connection
was carried out much more quickly and accurately than had
been possible when telephone operators at manual switchboards
made the connection.
Impact
The telephone has become the world’s most important communication
device. Most adults use it between six and eight times per
day, for personal and business calls. This widespread use has developed
because huge changes have occurred in telephones and telephone
networks. For example, automatic switching and the rotary
dial system were only the beginning of changes in phone calling.

Touch-tone dialing replaced Barnay’s electrical pulses with audio
tones outside the frequency of human speech. This much-improved
system can be used to send calls over much longer distances than
was possible with the rotary dial system, and it also interacts well
with both answering machines and computers.
Another advance in modern telephoning is the use of radio
transmission techniques in mobile phones, rendering telephone
cords obsolete. The mobile phone communicates with base stations
arranged in “cells” throughout the service area covered. As the user
changes location, the phone link automatically moves from cell to
cell in a cellular network.
In addition, the use of microwave, laser, and fiber-optic technologies
has helped to lengthen the distance over which phone calls can
be transmitted. These technologies have also increased the number
of messages that phone networks can handle simultaneously and
have made it possible to send radio and television programs (such
as cable television), scientific data (via modems), and written messages
(via facsimile, or “fax,” machines) over phone lines. Many
other advances in telephone technology are expected as society’s
needs change and new technology is developed.
See also Cell phone; Internet; Long-distance telephone; Telephone
switching; Touch-tone telephone.
Further Reading
Rotary dial telephone / 667
Aitken, William. Who Invented the Telephone? London: Blackie and
Son, 1939.
Coe, Lewis. The Telephone and Its Several Inventors: A History. Jefferson,
N.C.: McFarland, 1995.
Evenson, A. Edward. The Telephone Patent Conspiracy of 1876: The
Elisha Gray-Alexander Bell Controversy and Its Many Players. Jefferson,
N.C.: McFarland, 2000.
Lisser, Eleena de. “Telecommunications: If You Have a Rotary
Phone, Press 1: The Trials of Using the Old Apparatus.” Wall
Street Journal (July 28, 1994).
Mackay, James A. Alexander Graham Bell: A Life. New York: J. Wiley,
1997.

668
SAINT
SAINT
The invention: Taking its name from the acronym for symbolic automatic
integrator, SAINT is recognized as the first “expert system”—a
computer program designed to perform mental tasks requiring
human expertise.
The person behind the invention:
James R. Slagle (1934-1994), an American computer scientist
The Advent of Artificial Intelligence
In 1944, the Harvard-IBM Mark I was completed. This was an
electromechanical (that is, not fully electronic) digital computer
that was operated by means of coding instructions punched into
paper tape. The machine took about six seconds to perform a multiplication
operation, twelve for a division operation. In the following
year, 1945, the world’s first fully electronic digital computer,
the Electronic Numerical Integrator and Calculator (ENIAC),
became operational. This machine, which was constructed at the
University of Pennsylvania, was thirty meters long, three meters
high, and one meter deep.
At the same time that these machines were being built, a similar
machine was being constructed in the United Kingdom: the automated
computing engine (ACE). Akey figure in the British development
was Alan Turing, a mathematician who had used computers
to break German codes during World War II. After the war, Turing
became interested in the area of “computing machinery and intelligence.”
He posed the question “Can machines think?” and set the
following problem, which is known as the “Turing test.” This test
involves an interrogator who sits at a computer terminal and asks
questions on the terminal about a subject for which he or she seeks intelligent
answers. The interrogator does not know, however, whether
the system is linked to a human or if the responses are, in fact, generated
by a program that is acting intelligently. If the interrogator cannot
tell the difference between the human operator and the computer
system, then the system is said to have passed the Turing test
and has exhibited intelligent behavior.

SAINT: An Expert System
SAINT / 669
In the attempt to answer Turing’s question and create machines
that could pass the Turing test, researchers investigated techniques
for performing tasks that were considered to require expert levels of
knowledge. These tasks included games such as checkers, chess, and
poker. These games were chosen because the total possible number of
variations in each game was very large. This led the researchers to
several interesting questions for study. How do experts make a decision
in a particular set of circumstances? How can a problem such as
a game of chess be represented in terms of a computer program? Is it
possible to know why the system chose a particular solution?
One researcher, James R. Slagle at the Massachusetts Institute of
Technology, chose to develop a program that would be able to solve
elementary symbolic integration problems (involving the manipulation
of integrals in calculus) at the level of a good college freshman.
The program that Slagle constructed was known as SAINT, an
acronym for symbolic automatic integrator, and it is acknowledged
as the first “expert system.”
An expert system is a system that performs at the level of a human
expert. An expert system has three basic components: a knowledge
base, in which domain-specific information is held (for example, rules
on how best to perform certain types of integration problems); an inference
engine, which decides how to break down a given problem utilizing
the rules in the knowledge base; and a human-computer interface
that inputs data—in this case, the integral to be solved—and
outputs the result of performing the integration. Another feature of expert
systems is their ability to explain their reasoning.
The integration problems that could be solved by SAINT were
in the form of elementary integral functions. SAINT could perform
indefinite integration (also called “antidifferentiation”) on these
functions. In addition, it was capable of performing definite and
indefinite integration on trivial extensions of indefinite integration.
SAINT was tested on a set of eighty-six problems, fifty-four of
which were drawn from the MIT final examinations in freshman
calculus; it succeeded in solving all but two. Slagle added more
rules to the knowledge base so that problems of the type it encountered
but could not solve could be solved in the future.

670 / SAINT
The power of the SAINT system was, in part, based on its ability
to perform integration through the adoption of a “heuristic” processing
system. Aheuristic method is one that helps in discovering a
problem’s solution by making plausible but feasible guesses about
the best strategy to apply next to the current problem situation. A
heuristic is a rule of thumb that makes it possible to take short cuts
in reaching a solution, rather than having to go through every step
in a solution path. These heuristic rules are contained in the knowledge
base. SAINT was written in the LISP programming language
and ran on an IBM 7090 computer. The program and research were
Slagle’s doctoral dissertation.
Consequences
User
Interface
Global
Database
Control
Mechanism
Knowledge
Base
Basic structure of an expert system.
Facts
Search
and
Resolve
Rules
The SAINT system that Slagle developed was significant for several
reasons: First, it was the first serious attempt at producing a
program that could come close to passing the Turing test. Second, it
brought the idea of representing an expert’s knowledge in a computer
program together with strategies for solving complex and difficult
problems in an area that previously required human expertise.
Third, it identified the area of knowledge-based systems and

James R. Slagle
SAINT / 671
James R. Slagle was born in 1934 in Brooklyn, New York, and
attended nearby St. John’s University. He majored in mathematics
and graduated with a bachelor of science degree in 1955,
also winning the highest scholastic average award. While earning
his master’s degree (1957) and doctorate (1961) at the Massachusetts
Institute of Technology (MIT), he was a staff mathematician
in the university’s Lincoln Laboratory.
Slagle taught in MIT’s electrical engineering department
part-time after completing his dissertation on the first expert
computer system and then moved to Lawrence-Livermore
National Laboratory near Berkeley, California. While working
there he also taught at the University of California. From 1967
until 1974 he was an adjunct member of the computer science
faculty of Johns Hopkins University in Baltimore, Maryland,
and then was appointed chief of the computer science laboratory
at the Naval Research Laboratory (NRL) in Washington, D.C., receiving
the Outstanding Handicapped Federal Employee of the
Year Award in 1979. In 1984 he was made a special assistant in
the Navy Center for Applied Research in Artificial Intelligence
at NRL but left in 1984 to become Distinguished Professor of
Computer Science at the University of Minnesota.
In these various positions Slagle helped mature the fledgling
discipline of artificial intelligence, publishing the influential
book Artificial Intelligence in 1971. He developed an expert system
designed to set up other expert systems—A Generalized
Network-based Expert System Shell, or AGNESS. He also worked
on parallel expert systems, artificial neural networks, timebased
logic, and methods for uncovering causal knowledge in
large databases. He died in 1994.
showed that computers could feasibly be used for programs that
did not relate to business data processing. Fourth, the SAINT system
showed how the use of heuristic rules and information could
lead to the solution of problems that could not have been solved
previously because of the amount of time needed to calculate a solution.
SAINT’s major impact was in outlining the uses of these techniques,
which led to continued research in the subfield of artificial
intelligence that became known as expert systems.

672 / SAINT
See also BASIC programming language; CAD/CAM; COBOL
computer language; Differential analyzer; FORTRAN programming
language; Robot (industrial).
Further Reading
Campbell-Kelly, Martin, and William Aspray. Computer: A History of
the Information Machine. New York: Basic Books, 1996.
Ceruzzi, Paul E. A History of Modern Computing. Cambridge, Mass.:
MIT Press, 2000.
Rojas, Paul. Encyclopedia of Computers and Computer History. London:
Fitzroy Dearborn, 2001.

Salvarsan
Salvarsan
The invention: The first successful chemotherapeutic for the treatment
of syphilis
The people behind the invention:
Paul Ehrlich (1854-1915), a German research physician and
chemist
Wilhelm von Waldeyer (1836-1921), a German anatomist
Friedrich von Frerichs (1819-1885), a German physician and
professor
Sahachiro Hata (1872-1938), a Japanese physician and
bacteriologist
Fritz Schaudinn (1871-1906), a German zoologist
The Great Pox
673
The ravages of syphilis on humankind are seldom discussed
openly. A disease that struck all varieties of people and was transmitted
by direct and usually sexual contact, syphilis was both
feared and reviled. Many segments of society across all national
boundaries were secure in their belief that syphilis was divine punishment
of the wicked for their evil ways.
It was not until 1903 that bacteriologists Élie Metchnikoff and
Pierre-Paul-Émile Roux demonstrated the transmittal of syphilis to
apes, ending the long-held belief that syphilis was exclusively a human
disease. The disease destroyed families, careers, and lives,
driving its infected victims mad, destroying the brain, or destroying
the cardiovascular system. It was methodical and slow, but in every
case, it killed with singular precision. There was no hope of a safe
and effective cure prior to the discovery of Salvarsan.
Prior to 1910, conventional treatment consisted principally of
mercury or, later, potassium iodide. Mercury, however, administered
in large doses, led to severe ulcerations of the tongue, jaws,
and palate. Swelling of the gums and loosening of the teeth resulted.
Dribbling saliva and the attending fetid odor also occurred. These
side effects of mercury treatment were so severe that many pre-

674 / Salvarsan
ferred to suffer the disease to the end rather than undergo the standard
cure. About 1906, Metchnikoff and Roux demonstrated that
mercurial ointments, applied very early, at the first appearance of
the primary lesion, were effective.
Once the spirochete-type bacteria invaded the bloodstream and
tissues, the infected person experienced symptoms of varying nature
and degree—high fever, intense headaches, and excruciating
pain. The patient’s skin often erupted in pustular lesions similar in
appearance to smallpox. It was the distinguishing feature of these
pustular lesions that gave syphilis its other name: the “Great Pox.”
Death brought the only relief then available.
Poison Dyes
Paul Ehrlich became fascinated by the reactions of dyes with biological
cells and tissues while a student at the University of Strasbourg
under Wilhelm von Waldeyer. It was von Waldeyer who
sparked Ehrlich’s interest in the chemical viewpoint of medicine.
Thus, as a student, Ehrlich spent hours at this laboratory experimenting
with different dyes on various tissues. In 1878, he published
a book that detailed the discriminate staining of cells and cellular
components by various dyes.
Ehrlich joined Friedrich von Frerichs at the Charité Hospital in
Berlin, where Frerichs allowed Ehrlich to do as much research as he
wanted. Ehrlich began studying atoxyl in 1908, the year he won
jointly with Metchnikoff the Nobel Prize in Physiology or Medicine
for his work on immunity. Atoxyl was effective against trypanosome—a
parasite responsible for a variety of infections, notably
sleeping sickness—but also imposed serious side effects upon the
patient, not the least of which was blindness. It was Ehrlich’s study
of atoxyl, and several hundred derivatives sought as alternatives to
atoxyl in trypanosome treatment, that led to the development of derivative
606 (Salvarsan). Although compound 606 was the first
chemotherapeutic to be used effectively against syphilis, it was discontinued
as an atoxyl alternative and shelved as useless for five
years.
The discovery and development of compound 606 was enhanced
by two critical events. First, the Germans Fritz Schaudinn and Erich

The wonder drug Salvarsan was often called “Ehrlich’s silver bullet,” after its developer,
Paul Ehrlich (left). (Library of Congress)

676 / Salvarsan
Hoffmann discovered that syphilis is a bacterially caused disease.
The causative microorganism is a spirochete so frail and gossameric
in substance that it is nearly impossible to detect by casual microscopic
examination; Schaudinn chanced upon it one day in March,
1905. This discovery led, in turn, to German bacteriologist August
von Wassermann’s development of the now famous test for syphilis:
the Wassermann test. Second, a Japanese bacteriologist, Sahachiro
Hata, came to Frankfurt in 1909 to study syphilis with
Ehrlich. Hata had studied syphilis in rabbits in Japan. Hata’s assignment
was to test every atoxyl derivative ever developed under
Ehrlich for its efficacy in syphilis treatment. After hundreds of tests
and clinical trials, Ehrlich and Hata announced Salvarsan as a
“magic bullet” that could cure syphilis, at the April, 1910, Congress
of Internal Medicine in Wiesbaden, Germany.
The announcement was electrifying. The remedy was immediately
and widely sought, but it was not without its problems. A few deaths
resulted from its use, and it was not safe for treatment of the gravely ill.
Some of the difficulties inherent in Salvarsan were overcome by the development
of neosalvarsan in 1912 and sodium salvarsan in 1913. Although
Ehrlich achieved much, he fell short of his own assigned goal, a
chemotherapeutic that would cure in one injection.
Impact
The significance of the development of Salvarsan as an antisyphilitic
chemotherapeutic agent cannot be overstated. Syphilis at
that time was as frightening and horrifying as leprosy and was a virtual
sentence of slow, torturous death. Salvarsan was such a significant
development that Ehrlich was recommended for a 1912 and
1913 Nobel Prize for his work in chemotherapy.
It was several decades before any further significant advances in
“wonder drugs” occurred, namely, the discovery of prontosil in 1932
and its first clinical use in 1935. On the heels of prontosil—a sulfa
drug—came other sulfa drugs. The sulfa drugs would remain supreme
in the fight against bacterial infection until the antibiotics, the
first being penicillin, were discovered in 1928; however, they were
not clinically recognized until World War II (1939-1945). With the discovery
of streptomycin in 1943 and Aureomycin in 1944, the assault

against bacteria was finally on a sound basis. Medicine possessed an
arsenal with which to combat the pathogenic microbes that for centuries
before had visited misery and death upon humankind.
See also Abortion pill; Antibacterial drugs; Birth control pill;
Penicillin; Reserpine; Syphilis test; Tuberculosis vaccine; Typhus
vaccine; Yellow fever vaccine.
Further Reading
Salvarsan / 677
Bäumler, Ernst. Paul Ehrlich: Scientist for Life. New York: Holmes &
Meier, 1984.
Leyden, John G. “From Nobel Prize to Courthouse Battle: Paul
Ehrlich’s ‘Wonder Drug’ for Syphilis Won Him Acclaim but also
Led Critics to Hound Him.” Washington Post (July 27, 1999).
Quétel, Claude. History of Syphilis. Baltimore: Johns Hopkins University
Press, 1992.

678
Scanning tunneling microscope
Scanning tunneling microscope
The invention: A major advance on the field ion microscope, the
scanning tunneling microscope has pointed toward new directions
in the visualization and control of matter at the atomic
level.
The people behind the invention:
Gerd Binnig (1947- ), a West German physicist who was a
cowinner of the 1986 Nobel Prize in Physics
Heinrich Rohrer (1933- ), a Swiss physicist who was a
cowinner of the 1986 Nobel Prize in Physics
Ernst Ruska (1906-1988), a West German engineer who was a
cowinner of the 1986 Nobel Prize in Physics
Antoni van Leeuwenhoek (1632-1723), a Dutch naturalist
The Limit of Light
The field of microscopy began at the end of the seventeenth century,
when Antoni van Leeuwenhoek developed the first optical microscope.
In this type of microscope, a magnified image of a sample
is obtained by directing light onto it and then taking the light
through a lens system. Van Leeuwenhoek’s microscope allowed
him to observe the existence of life on a scale that is invisible to the
naked eye. Since then, developments in the optical microscope have
revealed the existence of single cells, pathogenic agents, and bacteria.
There is a limit, however, to the resolving power of optical microscopes.
Known as “Abbe’s barrier,” after the German physicist and
lens maker Ernst Abbe, this limit means that objects smaller than
about 400 nanometers (about a millionth of a millimeter) cannot be
viewed by conventional microscopes.
In 1925, the physicist Louis de Broglie predicted that electrons
would exhibit wave behavior as well as particle behavior. This prediction
was confirmed by Clinton J. Davisson and Lester H. Germer
of Bell Telephone Laboratories in 1927. It was found that highenergy
electrons have shorter wavelengths than low-energy electrons
and that electrons with sufficient energies exhibit wave-

lengths comparable to the diameter of the atom. In 1927, Hans
Busch showed in a mathematical analysis that current-carrying
coils behave like electron lenses and that they obey the same lens
equation that governs optical lenses. Using these findings, Ernst
Ruska developed the electron microscope in the early 1930’s.
By 1944, the German corporation of Siemens and Halske had
manufactured electron microscopes with a resolution of 7 nanometers;
modern instruments are capable of resolving objects as
small as 0.5 nanometer. This development made it possible to view
structures as small as a few atoms across as well as large atoms and
large molecules.
The electron beam used in this type of microscope limits the usefulness
of the device. First, to avoid the scattering of the electrons,
the samples must be put in a vacuum, which limits the applicability
of the microscope to samples that can sustain such an environment.
Most important, some fragile samples, such as organic molecules,
are inevitably destroyed by the high-energy beams required for
high resolutions.
Viewing Atoms
Scanning tunneling microscope / 679
From 1936 to 1955, Erwin Wilhelm Müller developed the field ion
microscope (FIM), which used an extremely sharp needle to hold the
sample. This was the first microscope to make possible the direct
viewing of atomic structures, but it was limited to samples capable of
sustaining the high electric fields necessary for its operation.
In the early 1970’s, Russel D. Young and Clayton Teague of the
National Bureau of Standards (NBS) developed the “topografiner,”
a new kind of FIM. In this microscope, the sample is placed at a large
distance from the tip of the needle. The tip is scanned across the surface
of the sample with a precision of about a nanometer. The precision
in the three-dimensional motion of the tip was obtained by using
three legs made of piezoelectric crystals. These materials change
shape in a reproducible manner when subjected to a voltage. The
extent of expansion or contraction of the crystal depends on the
amount of voltage that is applied. Thus, the operator can control the
motion of the probe by varying the voltage acting on the three legs.
The resolution of the topografiner is limited by the size of the probe.

680 / Scanning tunneling microscope
Gerd Binnig and Heinrich Rohrer
Both Gerd Binnig and Heinrich Rohrer believe an early and
pleasurable introduction to teamwork led to their later success
in inventing the scanning tunneling microscope, for which they
shared the 1986 Nobel Prize in Physics with Ernst Ruska.
Binnig was born in Frankfurt, Germany, in 1947. He acquired
an early interest in physics but was always deeply influenced
by classical music, introduced to him by his mother, and
the rock music that his younger brother played for him. Binnig
played in rock bands as a teenager and learned to enjoy the creative
interplay of teamwork. At J. W. Goethe University in
Frankfurt he earned a bachelor’s degree (1973) and doctorate
(1978) in physics and then took a position at International Business
Machine’s Zurich Research Laboratory. There he recaptured
the pleasures of working with a talented team after joining
Rohrer in research.
Rohrer had been at the Zurich facility since just after it
opened in 1963. He was born in Buch, Switzerland, in 1933, and
educated at the Swiss Federal Institute of Technology in Zurich,
where he completed his doctorate in 1960. After post-doctoral
work at Rutgers University, he joined the IBM research team, a
time that he describes as among the most enjoyable passages of
his career.
In addition to the Nobel Prize, the pair also received the German
Physics Prize, Otto Klung Prize, Hewlett Packard Prize,
and King Faisal Prize. Rohrer became an IBM Fellow in 1986
and was selected to manage the physical sciences department at
the Zurich Research Laboratory. He retired from IBM in July
1997. Binnig became an IBM Fellow in 1987.
The idea for the scanning tunneling microscope (STM) arose
when Heinrich Rohrer of the International Business Machines (IBM)
Corporation’s Zurich research laboratory met Gerd Binnig in Frankfurt
in 1978. The STM is very similar to the topografiner. In the STM,
however, the tip is kept at a height of less than a nanometer away
from the surface, and the voltage that is applied between the specimen
and the probe is low. Under these conditions, the electron
cloud of atoms at the end of the tip overlaps with the electron cloud
of atoms at the surface of the specimen. This overlapping results in a

measurable electrical current flowing through the vacuum or insulating
material existing between the tip and the sample. When the
probe is moved across the surface and the voltage between the
probe and sample is kept constant, the change in the distance between
the probe and the surface (caused by surface irregularities)
results in a change of the tunneling current.
Two methods are used to translate these changes into an image of
the surface. The first method involves changing the height of the
probe to keep the tunneling current constant; the voltage used to
change the height is translated by a computer into an image of the
surface. The second method scans the probe at a constant height
away from the sample; the voltage across the probe and sample is
changed to keep the tunneling current constant. These changes in
voltage are translated into the image of the surface. The main limitation
of the technique is that it is applicable only to conducting samples
or to samples with some surface treatment.
Consequences
Scanning tunneling microscope / 681
In October, 1989, the STM was successfully used in the manipulation
of matter at the atomic level. By letting the probe sink into the
surface of a metal-oxide crystal, researchers at Rutgers University
were able to dig a square hole about 250 atoms across and 10 atoms
deep. Amore impressive feat was reported in the April 5, 1990, issue
of Nature; M. Eigler and Erhard K. Schweiser of IBM’s Almaden Research
Center spelled out their employer’s three-letter acronym using
thirty-five atoms of xenon. This ability to move and place individual
atoms precisely raises several possibilities, which include the
creation of custom-made molecules, atomic-scale data storage, and
ultrasmall electrical logic circuits.
The success of the STM has led to the development of several
new microscopes that are designed to study other features of sample
surfaces. Although they all use the scanning probe technique to
make measurements, they use different techniques for the actual detection.
The most popular of these new devices is the atomic force
microscope (AFM). This device measures the tiny electric forces that
exist between the electrons of the probe and the electrons of the
sample without the need for electron flow, which makes the tech-

682 / Scanning tunneling microscope
nique particularly useful in imaging nonconducting surfaces. Other
scanned probe microscopes use physical properties such as temperature
and magnetism to probe the surfaces.
See also Cyclotron; Electron microscope; Ion field microscope;
Mass spectrograph; Neutrino detector; Sonar; Synchrocyclotron;
Tevatron accelerator; Ultramicroscope.
Further Reading
Morris, Michael D. Microscopic and Spectroscopic Imaging of the Chemical
State. New York: M. Dekker, 1993.
Wiesendanger, Robert. Scanning Probe Microscopy: Analytical Methods.
New York: Springer-Verlag, 1998.
_____, and Hans-Joachim Güntherodt. Scanning Tunneling Microscopy
II: Further Applications and Related Scanning Techniques.2ded.
New York: Springer, 1995.
_____. Scanning Tunneling Microscopy III: Theory of STM and Related
Scanning Probe Methods. 2d ed. New York: Springer, 1996.

Silicones
Silicones
The invention: Synthetic polymers characterized by lubricity, extreme
water repellency, thermal stability, and inertness that are
widely used in lubricants, protective coatings, paints, adhesives,
electrical insulation, and prosthetic replacements for body parts.
The people behind the invention:
Eugene G. Rochow (1909- ), an American research chemist
Frederic Stanley Kipping (1863-1949), a Scottish chemist and
professor
James Franklin Hyde (1903- ), an American organic chemist
Synthesizing Silicones
683
Frederic Stanley Kipping, in the first four decades of the twentieth
century, made an extensive study of the organic (carbon-based)
chemistry of the element silicon. He had a distinguished academic
career and summarized his silicon work in a lecture in 1937 (“Organic
Derivatives of Silicon”). Since Kipping did not have available
any naturally occurring compounds with chemical bonds between
carbon and silicon atoms (organosilicon compounds), it was necessary
for him to find methods of establishing such bonds. The basic
method involved replacing atoms in naturally occurring silicon
compounds with carbon atoms from organic compounds.
While Kipping was probably the first to prepare a silicone and was
certainly the first to use the term silicone, he did not pursue the commercial
possibilities of silicones. Yet his careful experimental work was
a valuable starting point for all subsequent workers in organosilicon
chemistry, including those who later developed the silicone industry.
On May 10, 1940, chemist Eugene G. Rochow of the General
Electric (GE) Company’s corporate research laboratory in
Schenectady, New York, discovered that methyl chloride gas,
passed over a heated mixture of elemental silicon and copper, reacted
to form compounds with silicon-carbon bonds. Kipping
had shown that these silicon compounds react with water to form
silicones.

684 / Silicones
The importance of Rochow’s discovery was that it opened the
way to a continuous process that did not consume expensive metals,
such as magnesium, or flammable ether solvents, such as those
used by Kipping and other researchers. The copper acts as a catalyst,
and the desired silicon compounds are formed with only minor
quantities of by-products. This “direct synthesis,” as it came to be
called, is now done commercially on a large scale.
Silicone Structure
Silicones are examples of what chemists call polymers. Basically, a
polymer is a large molecule made up of many smaller molecules
that are linked together. At the molecular level, silicones consist of
long, repeating chains of atoms. In this molecular characteristic, silicones
resemble plastics and rubber.
Silicone molecules have a chain composed of alternate silicon and
oxygen atoms. Each silicon atom bears two organic groups as substituents,
while the oxygen atoms serve to link the silicon atoms into a
chain. The silicon-oxygen backbone of the silicones is responsible for
their unique and useful properties, such as the ability of a silicone oil
to remain liquid over an extremely broad temperature range and to
resist oxidative and thermal breakdown at high temperatures.
A fundamental scientific consideration with silicone, as with any
polymer, is to obtain the desired physical and chemical properties in
a product by closely controlling its chemical structure and molecular
weight. Oily silicones with thousands of alternating silicon and
oxygen atoms have been prepared. The average length of the molecular
chain determines the flow characteristics (viscosity) of the oil.
In samples with very long chains, rubber-like elasticity can be
achieved by cross-linking the silicone chains in a controlled manner
and adding a filler such as silica. High degrees of cross-linking
could produce a hard, intractable material instead of rubber.
The action of water on the compounds produced from Rochow’s
direct synthesis is a rapid method of obtaining silicones, but does
not provide much control of the molecular weight. Further development
work at GE and at the Dow-Corning company showed that
the best procedure for controlled formation of silicone polymers involved
treating the crude silicones with acid to produce a mixture

Eugene G. Rochow
Silicones / 685
Eugene George Rochow was born in 1909 and grew up in the
rural New Jersey town of Maplewood. There his father, who
worked in the tanning industry, and his big brother maintained
a small attic laboratory. They experimented with electricity, radio—Eugene
put together his own crystal set in an oatmeal
box—and chemistry.
Rochow followed his brother to Cornell University in 1927.
The Great Depression began during his junior year, and although
he had to take jobs as lecture assistant to get by, he managed
to earn his bachelor’s degree in chemistry in 1931 and his
doctorate in 1935. Luck came his way in the extremely tight job
market: General Electric (GE) hired him for his expertise in inorganic
chemistry.
In 1938 the automobile industry, among other manufacturers,
had a growing need for a high-temperature-resistant insulators.
Scientists at Corning were convinced that silicone would
have the best properties for the purpose, but they could not find
a way to synthesize it cheaply and in large volume. When word
about their ideas got back to Rochow at GE, he reasoned that a
flexible silicone able to withstand temperatures of 200 to 300 degrees
Celsius could be made by bonding silicone to carbon. His
research succeeded in producing methyl silicone in 1939, and
he devised a way to make it cheaply in 1941. It was the first
commercially practical silicone. His process is still used.
After World War II GE asked him to work on an effort to
make aircraft carriers nuclear powered. However, Rochow was
a Quaker and pacifist, and he refused. Instead, he moved to
Harvard University as a chemistry professor in 1948 and remained
there until his retirement in 1970. As the founder of a
new branch of industrial chemistry, he received most of the discipline’s
awards and medals, including the Perkin Award, and
honorary doctorates.
from which high yields of an intermediate called “D4” could be obtained
by distillation. The intermediate D4 could be polymerized in
a controlled manner by use of acidic or basic catalysts. Wilton I.
Patnode of GE and James F. Hyde of Dow-Corning made important
advances in this area. Hyde’s discovery of the use of traces of potassium
hydroxide as a polymerization catalyst for D4 made possible

686 / Silicones
the manufacture of silicone rubber, which is the most commercially
valuable of all the silicones.
Impact
Although Kipping’s discovery and naming of the silicones occurred
from 1901 to 1904, the practical use and impact of silicones
started in 1940, with Rochow’s discovery of direct synthesis.
Production of silicones in the United States came rapidly enough
to permit them to have some influence on military supplies for
World War II (1939-1945). In aircraft communication equipment, extensive
waterproofing of parts by silicones resulted in greater reliability
of the radios under tropical conditions of humidity, where
condensing water could be destructive. Silicone rubber, because
of its ability to withstand heat, was used in gaskets under hightemperature
conditions, in searchlights, and in the engines on B-29
bombers. Silicone grease applied to aircraft engines also helped to
protect spark plugs from moisture and promote easier starting.
After World War II, the uses for silicones multiplied. Silicone rubber
appeared in many products from caulking compounds to wire insulation
to breast implants for cosmetic surgery. Silicone rubber boots were
used on the moon walks where ordinary rubber would have failed.
Silicones in their present form owe much to years of patient developmental
work in industrial laboratories. Basic research, such as
that conducted by Kipping and others, served to point the way and
catalyzed the process of commercialization.
See also Buna rubber; Neoprene; Nylon; Plastic; Polystyrene; Teflon.
Further Reading
Clarson, Stephen J. Silicones and Silicone-Modified Materials. Washington,
D.C.: American Chemical Society, 2000.
Koerner, G. Silicones, Chemistry and Technology. Boca Raton, Fla.:
CRC Press, 1991.
Potter, Michael, and Noel R. Rose. Immunology of Silicones. New
York: Springer, 1996.
Smith, A. Lee. The Analytical Chemistry of Silicones. New York: Wiley,
1991.

Solar thermal engine
Solar thermal engine
The invention: The first commercially practical plant for generating
electricity from solar energy.
The people behind the invention:
Frank Shuman (1862-1918), an American inventor
John Ericsson (1803-1889), an American engineer
Augustin Mouchout (1825-1911), a French physics professor
Power from the Sun
687
According to tradition, the Greek scholar Archimedes used
reflective mirrors to concentrate the rays of the Sun and set afire
the ships of an attacking Roman fleet in 212 b.c.e. The story illustrates
the long tradition of using mirrors to concentrate solar energy
from a large area onto a small one, producing very high
temperatures.
With the backing of Napoleon III, the Frenchman Augustin
Mouchout built, between 1864 and 1872, several steam engines
that were powered by the Sun. Mirrors concentrated the sun’s rays
to a point, producing a temperature that would boil water. The
steam drove an engine that operated a water pump. The largest engine
had a cone-shaped collector, or “axicon,” lined with silverplated
metal. The French government operated the engine for six
months but decided it was too expensive to be practical.
John Ericsson, the American famous for designing and building
the Civil War ironclad ship Monitor, built seven steam-driven
solar engines between 1871 and 1878. In Ericsson’s design,
rays were focused onto a line rather than a point. Long mirrors,
curved into a parabolic shape, tracked the Sun. The rays were focused
onto a water-filled tube mounted above the reflectors to
produce steam. The engineer’s largest engine, which used an 11- ×
16-foot trough-shaped mirror, delivered nearly 2 horsepower. Because
his solar engines were ten times more expensive than conventional
steam engines, Ericsson converted them to run on coal to
avoid financial loss.

688 / Solar thermal engine
Frank Shuman, a well-known inventor in Philadelphia, Pennsylvania,
entered the field of solar energy in 1906. The self-taught engineer
believed that curved, movable mirrors were too expensive. His
first large solar engine was a hot-box, or flat-plate, collector. It lay
flat on the ground and had blackened pipes filled with a liquid that
had a low boiling point. The solar-heated vapor ran a 3.5-horsepower
engine.
Shuman’s wealthy investors formed the Sun Power Company to
develop and construct the largest solar plant ever built. The site chosen
was in Egypt, but the plant was built near Shuman’s home for
testing before it was sent to Egypt.
When the inventor added ordinary flat mirrors to reflect more
sunlight into each collector, he doubled the heat production of the
collectors. The 572 trough-type collectors were assembled in twentysix
rows. Water was piped through the troughs and converted to
steam. A condenser converted the steam to water, which reentered
the collectors. The engine pumped 3,000 gallons of water per minute
and produced 14 horsepower per day; performance was expected to
improve 25 percent in the sunny climate of Egypt.
British investors requested that professor C. V. Boys review the
solar plant before it was shipped to Egypt. Boys pointed out that the
bottom of each collector was not receiving any direct solar energy;
in fact, heat was being lost through the bottom. He suggested that
each row of flat mirrors be replaced by a single parabolic reflector,
and Shuman agreed. Shuman thought Boys’s idea was original, but
he later realized it was based on Ericsson’s design.
The company finally constructed the improved plant in Meadi,
Egypt, a farming district on the Nile River. Five solar collectors,
spaced 25 feet apart, were built in a north-south line. Each was
about 200 feet long and 10 feet wide. Trough-shaped reflectors were
made of mirrors held in place by brass springs that expanded
and contracted with changing temperatures. The parabolic mirrors
shifted automatically so that the rays were always focused on the
boiler. Inside the 15-inch boiler that ran down the middle of the collector,
water was heated and converted to steam. The engine produced
more than 55 horsepower, which was enough to pump 6,000
gallons of water per minute.
The purchase price of Shuman’s solar plant was twice as high as

Solar thermal engine / 689
Trough-shaped collectors with flat mirrors (above) produced enough solar thermal energy to
pump 3,000 gallons of water per minute. Trough-shaped collectors with parabolic mirrors
(below) produced enough solar thermal energy to pump 6,000 gallons of water per minute.
that of a coal-fired plant, but its operating costs were far lower. In
Egypt, where coal was expensive, the entire purchase price would
be recouped in four years. Afterward, the plant would operate for
practically nothing. The first practical solar engine was now in operation,
providing enough energy to drive a large-scale irrigation system
in the floodplain of the Nile River.
By 1914, Shuman’s work was enthusiastically supported, and solar
plants were planned for India and Africa. Shuman hoped to
build 20,000 reflectors in the Sahara Desert and generate energy
equal to all the coal mined in one year, but the outbreak of World

690 / Solar thermal engine
War I ended his dreams of large-scale solar developments. The
Meadi project was abandoned in 1915, and Shuman died before the
war ended. Powerful nations lost interest in solar power and began
to replace coal with oil. Rich oil reserves were discovered in many
desert zones that were ideal locations for solar power.
Impact
Although World War I ended Frank Shuman’s career, his breakthrough
proved to the world that solar power held great promise for
the future. His ideas were revived in 1957, when the Soviet Union
planned a huge solar project for Siberia. A large boiler was fixed on
a platform 140 feet high. Parabolic mirrors, mounted on 1,300 railroad
cars, revolved on circular tracks to focus light on the boiler. The
full-scale model was never built, but the design inspired the solar
power tower.
In the Mojave desert near Barstow, California, an experimental
power tower, Solar One, began operation in 1982. The system collects
solar energy to deliver steam to turbines that produce electric
power. The 30-story tower is surrounded by more than 1,800 mirrors
that adjust continually to track the Sun. Solar One generates
about 10 megawatts per day, enough power for 5,000 people.
Solar One was expensive, but future power towers will generate
electricity as cheaply as fossil fuels can. If the costs of the air and
water pollution caused by coal burning were considered, solar power
plants would already be recognized as cost effective. Meanwhile,
Frank Shuman’s success in establishing and operating a thoroughly
practical large-scale solar engine continues to inspire research and
development.
See also Compressed-air-accumulating power plant; Fuel cell;
Geothermal power; Nuclear power plant; Photoelectric cell; Photovoltaic
cell; Tidal power plant.
Further Reading
De Kay, James T. Monitor: The Story of the Legendary Civil War Ironclad
and the Man Whose Invention Changed the Course of History. New
York: Ballantine, 1999.

Solar thermal engine / 691
Mancini, Thomas R., James M. Chavez, and Gregory J. Kolb. “Solar
Thermal Power Today and Tomorrow.” Mechanical Engineering
116, no. 8 (August, 1994).
Moore, Cameron M. “Cooking Up Electricity with Sunlight.” The
World & I 12, no. 7 (July, 1997).
Parrish, Michael. “Enron Makes Electrifying Proposal Energy: The
Respected Developer Announces a Huge Solar Plant and a Breakthrough
Price.” Los Angeles Times (November 5, 1994).

692
Sonar
Sonar
The invention: A device that detects soundwaves transmitted
through water, sonar was originally developed to detect enemy
submarines but is also used in navigation, fish location, and
ocean mapping.
The people behind the invention:
Jacques Curie (1855-1941), a French physicist
Pierre Curie (1859-1906), a French physicist
Paul Langévin (1872-1946), a French physicist
Active Sonar, Submarines, and Piezoelectricity
Sonar, which stands for sound navigation and ranging, is the
American name for a device that the British call “asdic.” There are
two types of sonar. Active sonar, the more widely used of the two
types, detects and locates underwater objects when those objects reflect
sound pulses sent out by the sonar. Passive sonar merely listens
for sounds made by underwater objects. Passive sonar is used
mostly when the loud signals produced by active sonar cannot be
used (for example, in submarines).
The invention of active sonar was the result of American, British,
and French efforts, although it is often credited to Paul Langévin,
who built the first working active sonar system by 1917. Langévin’s
original reason for developing sonar was to locate icebergs, but the
horrors of German submarine warfare in World War I led to the new
goal of submarine detection. Both Langévin’s short-range system
and long-range modern sonar depend on the phenomenon of “piezoelectricity,”
which was discovered by Pierre and Jacques Curie in
1880. (Piezoelectricity is electricity that is produced by certain materials,
such as certain crystals, when they are subjected to pressure.)
Since its invention, active sonar has been improved and its capabilities
have been increased. Active sonar systems are used to detect
submarines, to navigate safely, to locate schools of fish, and to map
the oceans.

Sonar Theory, Development, and Use
Sonar / 693
Although active sonar had been developed by 1917, it was not
available for military use until World War II. An interesting major
use of sonar before that time was measuring the depth of the ocean.
That use began when the 1922 German Meteor Oceanographic Expedition
was equipped with an active sonar system. The system
was to be used to help pay German World War I debts by aiding in
the recovery of gold from wrecked vessels. It was not used successfully
to recover treasure, but the expedition’s use of sonar to determine
ocean depth led to the discovery of the Mid-Atlantic Ridge.
This development revolutionized underwater geology.
Active sonar operates by sending out sound pulses, often called
“pings,” that travel through water and are reflected as echoes when
they strike large objects. Echoes from these targets are received by
the system, amplified, and interpreted. Sound is used instead of
light or radar because its absorption by water is much lower. The
time that passes between ping transmission and the return of an
echo is used to identify the distance of a target from the system by
means of a method called “echo ranging.” The basis for echo ranging
is the normal speed of sound in seawater (5,000 feet per second).
The distance of the target from the radar system is calculated by
means of a simple equation: range = speed of sound × 0.5 elapsed
time. The time is divided in half because it is made up of the time
taken to reach the target and the time taken to return.
The ability of active sonar to show detail increases as the energy
of transmitted sound pulses is raised by decreasing the
sound wavelength. Figuring out active sonar data is complicated
by many factors. These include the roughness of the ocean, which
scatters sound and causes the strength of echoes to vary, making
it hard to estimate the size and identity of a target; the speed of
the sound wave, which changes in accordance with variations in
water temperature, pressure, and saltiness; and noise caused by
waves, sea animals, and ships, which limits the range of active sonar
systems.
A simple active pulse sonar system produces a piezoelectric signal
of a given frequency and time duration. Then, the signal is amplified
and turned into sound, which enters the water. Any echo

694 / Sonar
that is produced returns to the system to be amplified and used to
determine the identity and distance of the target.
Most active sonar systems are mounted near surface vessel keels
or on submarine hulls in one of three ways. The first and most popular
mounting method permits vertical rotation and scanning of a
section of the ocean whose center is the system’s location. The second
method, which is most often used in depth sounders, directs
the beam downward in order to measure ocean depth. The third
method, called wide scanning, involves the use of two sonar systems,
one mounted on each side of the vessel, in such a way that the
two beams that are produced scan the whole ocean at right angles to
the direction of the vessel’s movement.
Active single-beam sonar operation applies an alternating voltage
to a piezoelectric crystal, making it part of an underwater loudspeaker
(transducer) that creates a sound beam of a particular frequency.
When an echo returns, the system becomes an underwater
microphone (receiver) that identifies the target and determines its
range. The sound frequency that is used is determined by the sonar’s
Sonar
Active sonar detects and locates underwater objects that reflect sound pulses sent out by the
sonar.

purpose and the fact that the absorption of sound by water increases
with frequency. For example, long-range submarine-seeking sonar
systems (whose detection range is about ten miles) operate at 3 to 40
kilohertz. In contrast, short-range systems that work at about 500 feet
(in mine sweepers, for example) use 150 kilohertz to 2 megahertz.
Impact
Paul Langévin
If he had not published the Special Theory of Relativity in
1905, Albert Einstein once said, Paul Langévin would have
done so not long afterward. Born in Paris in 1872, Langévin was
among the foremost physicists of his generation. He studied in
the best French schools of science—and with such teachers as
Pierre Curie and Jean Perrin—and became a professor of physics
at the College de France in 1904. He moved to the Sorbonne
in 1909.
Langévin’s research was always widely influential. In addition
to his invention of active sonar, he was especially noted for
his studies of the molecular structure of gases, analysis of secondary
X rays from irradiated metals, his theory of magnetism,
and work on piezoelectricity and piezoceramics. His suggestion
that magnetic properties are linked to the valence electrons of atoms
inspired Niels Bohr’s classic model of the atom. In his later
career, a champion of Einstein’s theories of relativity, Langévin
worked on the implications of the space-time continuum.
During World War II, Langévin, a pacifist, publicly denounced
the Nazis and their occupation of France. They jailed him for it.
He escaped to Switzerland in 1944, returning as soon as France
was liberated. He died in late 1946.
Sonar / 695
Modern active sonar has affected military and nonmilitary activities
ranging from submarine location to undersea mapping and
fish location. In all these uses, two very important goals have been
to increase the ability of sonar to identify a target and to increase the
effective range of sonar. Much work related to these two goals has
involved the development of new piezoelectric materials and the replacement
of natural minerals (such as quartz) with synthetic piezoelectric
ceramics.

696 / Sonar
Efforts have also been made to redesign the organization of sonar
systems. One very useful development has been changing beammaking
transducers from one-beam units to multibeam modules
made of many small piezoelectric elements. Systems that incorporate
these developments have many advantages, particularly the ability
to search simultaneously in many directions. In addition, systems
have been redesigned to be able to scan many echo beams simultaneously
with electronic scanners that feed into a central receiver.
These changes, along with computer-aided tracking and target
classification, have led to the development of greatly improved active
sonar systems. It is expected that sonar systems will become
even more powerful in the future, finding uses that have not yet
been imagined.
See also Aqualung; Bathyscaphe; Bathysphere; Geiger counter;
Gyrocompass; Radar; Richter scale; Ultrasound.
Further Reading
Curie, Marie. Pierre Curie. New York: Dover Publications, 1923.
Hackmann, Willem Dirk. Seek and Strike: Sonar, Anti-Submarine Warfare,
and the Royal Navy, 1914-54. London: H.M.S.O., 1984.
Segrè, Emilio. From X-Rays to Quarks: Modern Physicists and Their
Discoveries. San Francisco: W. H. Freeman, 1980.
Senior, John E. Marie and Pierre Curie. Gloucestershire: Sutton, 1998.

Stealth aircraft
Stealth aircraft
The invention: The first generation of “radar-invisible” aircraft,
stealth planes were designed to elude enemy radar systems.
The people behind the invention:
Lockhead Corporation, an American research and development firm
Northrop Corporation, an American aerospace firm
Radar
During World War II, two weapons were developed that radically
altered the thinking of the U.S. military-industrial establishment
and the composition of U.S. military forces. These weapons
were the atomic bombs that were dropped on the Japanese cities of
Hiroshima and Nagasaki by U.S. forces and “radio detection and
ranging,” or radar. Radar saved the English during the Battle of Britain,
and it was radar that made it necessary to rethink aircraft design.
With radar, attacking aircraft can be detected hundreds of
miles from their intended targets, which makes it possible for those
aircraft to be intercepted before they can attack. During World
War II, radar, using microwaves, was able to relay the number, distance,
direction, and speed of German aircraft to British fighter interceptors.
This development allowed the fighter pilots of the Royal
Air Force, “the few” who were so highly praised by Winston Churchill,
to shoot down four times as many planes as they lost.
Because of the development of radar, American airplane design
strategy has been to reduce the planes’ cross sections, reduce or
eliminate the use of metal by replacing it with composite materials,
and eliminate the angles that are found on most aircraft control surfaces.
These actions help make aircraft less visible—and in some
cases, almost invisible—to radar. The Lockheed F-117A Nightrider
and the Northrop B-2 Stealth Bomber are the results of these efforts.
Airborne “Ninjas”
697
Hidden inside Lockheed Corporation is a research and development
organization that is unique in the corporate world. This

698 / Stealth aircraft
facility has provided the Air Force with the Sidewinder heatseeking
missile; the SR-71, a titanium-skinned aircraft that can fly
at four times the speed of sound; and, most recently, the F-117A
Nightrider. The Nightrider eluded Iraqi radar so effectively during
the 1991 Persian Gulf War that the Iraqis nicknamed it Shaba,
which is an Arabic word that means ghost. In an unusual move
for military projects, the Nightrider was delivered to the Air
Force in 1982, before the plane had been perfected. This was done
so that Air Force pilots could test fly the plane and provide input
that could be used to improve the aircraft before it went into full
production.
The Northrop B-2 Stealth Bomber was the result of a design philosophy
that was completely different from that of the F-117A
Nightrider. The F-117A, for example, has a very angular appearance,
but the angles are all greater than 180 degrees. This configuration
spreads out radar waves rather than allowing them to be concentrated
and sent back to their point of origin. The B-2, however,
stays away from angles entirely, opting for a smooth surface that
also acts to spread out the radar energy. (The B-2 so closely resembles
the YB-49 Flying Wing, which was developed in the late 1940’s,
that it even has the same wingspan.) The surface of the aircraft is
covered with radar-absorbing material and carries its engines and
weapons inside to reduce the radar cross section. There are no vertical
control surfaces, which has the disadvantage of making the aircraft
unstable, so the stabilizing system uses computers to make
small adjustments in the control elements on the trailing edges of
the wings, thus increasing the craft’s stability.
The F-117A Nightrider and the B-2 Stealth Bomber are the “ninjas”
of military aviation. Capable of striking powerfully, rapidly,
and invisibly, these aircraft added a dimension to the U.S. Air Force
that did not exist previously. Before the advent of these aircraft, missions
that required radar-avoidance tactics had to be flown below
the horizon of ground-based radar, which is 30.5 meters above the
ground. Such low-altitude flight is dangerous because of both the
increased difficulty of maneuvering and vulnerability to ground
fire. Additionally, such flying does not conceal the aircraft from the
airborne radar carried by such craft as the American E-3A AWACS
and the former Soviet Mainstay. In a major conflict, the only aircraft

that could effectively penetrate enemy airspace would be the Nightrider
and the B-2.
The purpose of the B-2 was to carry nuclear weapons into hostile
airspace undetected. With the demise of the Soviet Union, mainland
China seemed the only remaining major nuclear threat. For this reason,
many defense experts believed that there was no longer a need
for two radar-invisible planes, and cuts in U.S. military expenditures
threatened the B-2 program during the early 1990’s.
Consequences
The development of the Nightrider and the B-2 meant that the
former Soviet Union would have had to spend at least $60 billion to
upgrade its air defense forces to meet the challenge offered by these
aircraft. This fact, combined with the evolution of the Strategic Defense
Initiative, commonly called “Star Wars,” led to the United
States’ victory in the arms race. Additionally, stealth technology has
found its way onto the conventional battlefield.
As was shown in 1991 during the Desert Storm campaign in Iraq,
targets that have strategic importance are often surrounded by a
network of anti-air missiles and gun emplacements. During the
Desert Storm air war, the F-117A was the only Allied aircraft to be
assigned to targets in Baghdad. Nightriders destroyed more than 47
percent of the strategic areas that were targeted, and every pilot and
plane returned to base unscathed.
Since the world appears to be moving away from superpower
conflicts and toward smaller regional conflicts, stealth aircraft may
come to be used more for surveillance than for air attacks. This is
particularly true because the SR-71, which previously played the
primary role in surveillance, has been retired from service.
See also Airplane; Cruise missile; Hydrogen bomb; Radar;
Rocket; Turbojet; V-2 rocket.
Further Reading
Stealth aircraft / 699
Chun, Clayton K. S. The Lockheed F-117A. Santa Monica, Calif.: Rand,
1991.

700 / Stealth aircraft
Goodall, James C. America’s Stealth Fighters and Bombers. Osceola,
Wis.: Motorbooks, 1992.
Pape, Garry R., and John M. Campbell. Northrop Flying Wings: A History
of Jack Northrop’s Visionary Aircraft. Atglen, Pa.: Schiffer, 1995.
Thornborough, Anthony M. Stealth. London: Ian Allen, 1991.

Steelmaking process
Steelmaking process
The invention: Known as the basic oxygen, or L-D, process, a
method for producing steel that worked about twelve times
faster than earlier methods.
The people behind the invention:
Henry Bessemer (1813-1898), the English inventor of a process
for making steel from iron
Robert Durrer (1890-1978), a Swiss scientist who first proved
the workability of the oxygen process in a laboratory
F. A. Loosley (1891-1966), head of research and development at
Dofasco Steel in Canada
Theodor Suess (1894-1956), works manager at Voest
Ferrous Metal
701
The modern industrial world is built on ferrous metal. Until
1857, ferrous metal meant cast iron and wrought iron, though a few
specialty uses of steel, especially for cutlery and swords, had existed
for centuries. In 1857, Henry Bessemer developed the first largescale
method of making steel, the Bessemer converter. By the 1880’s,
modification of his concepts (particularly the development of a ‘’basic”
process that could handle ores high in phosphor) had made
large-scale production of steel possible.
Bessemer’s invention depended on the use of ordinary air, infused
into the molten metal, to burn off excess carbon. Bessemer himself
had recognized that if it had been possible to use pure oxygen instead
of air, oxidation of the carbon would be far more efficient and rapid.
Pure oxygen was not available in Bessemer’s day, except at very high
prices, so steel producers settled for what was readily available, ordinary
air. In 1929, however, the Linde-Frakl process for separating the
oxygen in air from the other elements was discovered, and for the
first time inexpensive oxygen became available.
Nearly twenty years elapsed before the ready availability of pure
oxygen was applied to refining the method of making steel. The first
experiments were carried out in Switzerland by Robert Durrer. In

702 / Steelmaking process
1949, he succeeded in making steel expeditiously in a laboratory setting
through the use of a blast of pure oxygen. Switzerland, however,
had no large-scale metallurgical industry, so the Swiss turned
the idea over to the Austrians, who for centuries had exploited the
large deposits of iron ore in a mountain in central Austria. Theodor
Suess, the works manager of the state-owned Austrian steel complex,
Voest, instituted some pilot projects. The results were sufficiently
favorable to induce Voest to authorize construction of production
converters. In 1952, the first ‘’heat” (as a batch of steel is
called) was “blown in,” at the Voest works in Linz. The following
year, another converter was put into production at the works in
Donauwitz. These two initial locations led to the basic oxygen process
sometimes being referred to as the L-D process.
The L-D Process
The basic oxygen, or L-D, process makes use of a converter similar
to the Bessemer converter. Unlike the Bessemer, however, the L-
D converter blows pure oxygen into the molten metal from above
through a water-cooled injector known as a lance. The oxygen burns
off the excess carbon rapidly, and the molten metal can then be
poured off into ingots, which can later be reheated and formed into
the ultimately desired shape. The great advantage of the process is
the speed with which a “heat” reaches the desirable metallurgical
composition for steel, with a carbon content between 0.1 percent
and 2 percent. The basic oxygen process requires about forty minutes.
In contrast, the prevailing method of making steel, using an
open-hearth furnace (which transferred the technique from the
closed Bessemer converter to an open-burning furnace to which the
necessary additives could be introduced by hand) requires eight to
eleven hours for a “heat” or batch.
The L-D process was not without its drawbacks, however. It was
adopted by the Austrians because, by carefully calibrating the timing
and amount of oxygen introduced, they could turn their moderately
phosphoric ore into steel without further intervention. The
process required ore of a standardized metallurgical, or chemical,
content, for which the lancing had been calculated. It produced a
large amount of iron-oxide dust that polluted the surrounding at-

Steelmaking process / 703
mosphere, and it required a lining in the converter of dolomitic
brick. The specific chemical content of the brick contributed to the
chemical mixture that produced the desired result.
The Austrians quickly realized that the process was an improvement.
In May, 1952, the patent specifications for the new process
were turned over to a new company, Brassert Oxygen Technik, or
BOT, which filed patent applications around the world. BOT embarked
on an aggressive marketing campaign, bringing potential
customers to Austria to observe the process in action. Despite BOT’s
efforts, the new process was slow to catch on, even though in 1953
BOT licensed a U.S. firm, Kaiser Engineers, to spread the process in
the United States.
Many factors serve to explain the reluctance of steel producers
around the world to adopt the new process. One of these was the
large investment most major steel producers had in their openhearth
furnaces. Another was uncertainty about the pollution factor.
Later, special pollution-control equipment would be developed
to deal with this problem. A third concern was whether the necessary
refractory liners for the new converters would be available. A
fourth was the fact that the new process could handle a load that
contained no more than 30 percent scrap, preferably less. In practice,
therefore, it would only work where a blast furnace smelting
ore was already set up.
One of the earliest firms to show serious interest in the new technology
was Dofasco, a Canadian steel producer. Between 1952 and
1954, Dofasco, pushed by its head of research and development, F.
A. Loosley, built pilot operations to test the methodology. The results
were sufficiently promising that in 1954 Dofasco built the first
basic oxygen furnace outside Austria. Dofasco had recently built its
own blast furnace, so it had ore available on site. It was able to devise
ways of dealing with the pollution problem, and it found refractory
liners that would work. It became the first North American
producer of basic oxygen steel.
Having bought the licensing rights in 1953, Kaiser Engineers was
looking for a U.S. steel producer adventuresome enough to invest in
the new technology. It found that producer in McLouth Steel, a
small steel plant in Detroit, Michigan. Kaiser Engineers supplied
much of the technical advice that enabled McLouth to build the first

704 / Steelmaking process
U.S. basic oxygen steel facility, though McLouth also sent one of its
engineers to Europe to observe the Austrian operations. McLouth,
which had backing from General Motors, also made use of technical
descriptions in the literature.
The Specifications Question
Henry Bessemer
Henry Bessemer was born in the small village of Charlton,
England, in 1813. His father was an early example of a technician,
specializing in steam engines, and operated a business
making metal type for printing presses. The elder Bessemer
wanted his son to attend university, but Henry preferred to
study under his father. During his apprenticeship, he learned
the properties of alloys. At seventeen he moved to London to
open his own business, which fabricated specialty metals.
Three years later the Royal Academy held an exhibition of
Bessemer’s work. His career, well begun, moved from one invention
to another until at his death in 1898 he held 114 patents.
Among them were processes for casting type and producing
graphite for pencils; methods for manufacturing glass, sugar,
bronze powder, and ships; and his best known creation, the Bessemer
converter for making steel from iron. Bessemer built his
first converter in 1855; fifteen years later Great Britain was producing
half of the world’s steel.
Bessemer’s life and career were models of early Industrial
Age industry, prosperity, and longevity. A millionaire from patent
royalties, he retired at fifty-nine, lived another twenty-six
years, working on yet more inventions and cultivating astronomy
as a hobby, and was married for sixty-four years. Among
his many awards and honors was a knighthood, bestowed by
Queen Victoria.
One factor that held back adoption of basic oxygen steelmaking
was the question of specifications. Many major engineering projects
came with precise specifications detailing the type of steel to be
used and even the method of its manufacture. Until basic oxygen
steel was recognized as an acceptable form by the engineering fra-

Steelmaking process / 705
ternity, so that job specifications included it as appropriate in specific
applications, it could not find large-scale markets. It took a
number of years for engineers to modify their specifications so that
basic oxygen steel could be used.
The next major conversion to the new steelmaking process occurred
in Japan. The Japanese had learned of the process early,
while Japanese metallurgical engineers were touring Europe in
1951. Some of them stopped off at the Voest works to look at the pilot
projects there, and they talked with the Swiss inventor, Robert
Durrer. These engineers carried knowledge of the new technique
back to Japan. In 1957 and 1958, Yawata Steel and Nippon Kokan,
the largest and third-largest steel producers in Japan, decided to implement
the basic oxygen process. An important contributor to this
decision was the Ministry of International Trade and Industry, which
brokered a licensing arrangement through Nippon Kokan, which in
turn had signed a one-time payment arrangement with BOT. The
licensing arrangement allowed other producers besides Nippon
Kokan to use the technique in Japan.
The Japanese made two important technical improvements in
the basic oxygen technology. They developed a multiholed lance for
blowing in oxygen, thus dispersing it more effectively in the molten
metal and prolonging the life of the refractory lining of the converter
vessel. They also pioneered the OG process for recovering
some of the gases produced in the converter. This procedure reduced
the pollution generated by the basic oxygen converter.
The first large American steel producer to adopt the basic oxygen
process was Jones and Laughlin, which decided to implement the
new process for several reasons. It had some of the oldest equipment
in the American steel industry, ripe for replacement. It also
had experienced significant technical difficulties at its Aliquippa
plant, difficulties it was unable to solve by modifying its openhearth
procedures. It therefore signed an agreement with Kaiser Engineers
to build some of the new converters for Aliquippa. These
converters were constructed on license from Kaiser Engineers by
Pennsylvania Engineering, with the exception of the lances, which
were imported from Voest in Austria. Subsequent lances, however,
were built in the United States. Some of Jones and Laughlin’s production
managers were sent to Dofasco for training, and technical

706 / Steelmaking process
advisers were brought to the Aliquippa plant both from Kaiser Engineers
and from Austria.
Other European countries were somewhat slower to adopt the
new process. A major cause for the delay was the necessary modification
of the process to fit the high phosphoric ores available in Germany
and France. Europeans also experimented with modifications
of the basic oxygen technique by developing converters that revolved.
These converters, known as Kaldo in Sweden and Rotor in
Germany, proved in the end to have sufficient technical difficulties
that they were abandoned in favor of the standard basic oxygen
converter. The problems they had been designed to solve could be
better dealt with through modifications of the lance and through
adjustments in additives.
By the mid-1980’s, the basic oxygen process had spread throughout
the world. Neither Japan nor the European Community was
producing any steel by the older, open-hearth method. In conjunction
with the electric arc furnace, fed largely on scrap metal, the basic
oxygen process had transformed the steel industry of the world.
Impact
The basic oxygen process has significant advantages over older
procedures. It does not require additional heat, whereas the openhearth
technique calls for the infusion of nine to twelve gallons of
fuel oil to raise the temperature of the metal to the level necessary to
burn off all the excess carbon. The investment cost of the converter
is about half that of an open-hearth furnace. Fewer refractories are
required, less than half those needed in an open-hearth furnace.
Most important of all, however, a “heat” requires less than an hour,
as compared with the eight or more hours needed for a “heat” in an
open-hearth furnace.
There were some disadvantages to the basic oxygen process. Perhaps
the most important was the limited amount of scrap that could
be included in a “heat,” a maximum of 30 percent. Because the process
required at least 70 percent new ore, it could be operated most
effectively only in conjunction with a blast furnace. Counterbalancing
this last factor was the rapid development of the electric arc
furnace, which could operate with 100 percent scrap. A firm with its

Steelmaking process / 707
own blast furnace could, with both an oxygen converter and an electric
arc furnace, handle the available raw material.
The advantages of the basic oxygen process overrode the disadvantages.
Some other new technologies combined to produce this
effect. The most important of these was continuous casting. Because
of the short time required for a “heat,” it was possible, if a plant had
two or three converters, to synchronize output with the fill needs of
a continuous caster, thus largely canceling out some of the economic
drawbacks of the batch process. Continuous production, always
more economical, was now possible in the basic steel industry, particularly
after development of computer-controlled rolling mills.
These new technologies forced major changes in the world’s steel
industry. Labor requirements for the basic oxygen converter were
about half those for the open-hearth furnace. The high speed of the
new technology required far less manual labor but much more technical
expertise. Labor requirements were significantly reduced, producing
major social dislocations in steel-producing regions. This effect
was magnified by the fact that demand for steel dropped
sharply in the 1970’s, further reducing the need for steelworkers.
The U.S. steel industry was slower than either the Japanese or the
European to convert to the basic oxygen technique. The U.S. industry
generally operated with larger quantities, and it took a number
of years before the basic oxygen technique was adapted to converters
with an output equivalent to that of the open-hearth furnace. By
the time that had happened, world steel demand had begun to
drop. U.S. companies were less profitable, failing to generate internally
the capital needed for the major investment involved in
abandoning open-hearth furnaces for oxygen converters. Although
union contracts enabled companies to change work assignments
when new technologies were introduced, there was stiff resistance
to reducing employment of steelworkers, most of whom had lived
all their lives in one-industry towns. Finally, engineers at the steel
firms were wedded to the old methods and reluctant to change, as
were the large bureaucracies of the big U.S. steel firms.
The basic oxygen technology in steel is part of a spate of new
technical developments that have revolutionized industrial production,
drastically reducing the role of manual labor and dramatically
increasing the need for highly skilled individuals with technical ex-

708 / Steelmaking process
pertise. Because capital costs are significantly lower than for alternative
processes, it has allowed a number of developing countries
to enter a heavy industry and compete successfully with the old industrial
giants. It has thus changed the face of the steel industry.
See also Assembly line; Buna rubber; Disposable razor; Laminated
glass; Memory metal; Neoprene; Oil-well drill bit; Pyrex
glass.
Further Reading
Bain, Trevor. Banking the Furnace: Restructuring of the Steel Industry in
Eight Countries. Kalamazoo, Mich.: W. E. Upjohn Institute for Employment
Research, 1992.
Gold, Bela, Gerhard Rosegger, and Myles G. Boylan, Jr. Evaluating
Technological Innovations: Methods, Expectations, and Findings. Lexington,
Mass.: Lexington Books, 1980.
Hall, Christopher. Steel Phoenix: The Fall and Rise of the U.S. Steel Industry.
New York: St. Martin’s Press, 1997.
Hoerr, John P. And the Wolf Finally Came: The Decline of the American
Steel Industry. Pittsburgh, Pa.: University of Pittsburgh Press,
1988.
Lynn, Leonard H. How Japan Innovates: A Comparison with the United
States in the Case of Oxygen Steelmaking. Boulder, Colo.: Westview
Press, 1982.
Seely, Burce Edsall. Iron and Steel in the Twentieth Century. New York:
Facts on File, 1994.

Supercomputer
Supercomputer
The invention: A computer that had the greatest computational
power that then existed.
The person behind the invention:
Seymour R. Cray (1928-1996), American computer architect and
designer
The Need for Computing Power
Although modern computers have roots in concepts first proposed
in the early nineteenth century, it was only around 1950 that they became
practical. Early computers enabled their users to calculate equations
quickly and precisely, but it soon became clear that even more
powerful computers—machines capable of receiving, computing, and
sending out data with great precision and at the highest speeds—
would enable researchers to use computer “models,” which are programs
that simulate the conditions of complex experiments.
Few computer manufacturers gave much thought to building the
fastest machine possible, because such an undertaking is expensive
and because the business use of computers rarely demands the
greatest processing power. The first company to build computers
specifically to meet scientific and governmental research needs was
Control Data Corporation (CDC). The company had been founded
in 1957 by William Norris, and its young vice president for engineering
was the highly respected computer engineer Seymour R.
Cray. When CDC decided to limit high-performance computer design,
Cray struck out on his own, starting Cray Research in 1972. His
goal was to design the most powerful computer possible. To that
end, he needed to choose the principles by which his machine
would operate; that is, he needed to determine its architecture.
The Fastest Computer
709
All computers rely upon certain basic elements to process data.
Chief among these elements are the central processing unit, or CPU

710 / Supercomputer
(which handles data), memory (where data are stored temporarily
before and after processing), and the bus (the interconnection between
memory and the processor, and the means by which data are
transmitted to or from other devices, such as a disk drive or a monitor).
The structure of early computers was based on ideas developed
by the mathematician John von Neumann, who, in the 1940’s,
conceived a computer architecture in which the CPU controls all
events in a sequence: It fetches data from memory, performs calculations
on those data, and then stores the results in memory. Because it
functions in sequential fashion, the speed of this “scalar processor”
is limited by the rate at which the processor is able to complete each
cycle of tasks.
Before Cray produced his first supercomputer, other designers
tried different approaches. One alternative was to link a vector processor
to a scalar unit. A vector processor achieves its speed by performing
computations on a large series of numbers (called a vector)
at one time rather than in sequential fashion, though specialized
and complex programs were necessary to make use of this feature.
In fact, vector processing computers spent most of their time operating
as traditional scalar processors and were not always efficient at
switching back and forth between the two processing types.
Another option chosen by Cray’s competitors was the notion of
“pipelining” the processor’s tasks. A scalar processor often must
wait while data are retrieved or stored in memory. Pipelining techniques
allow the processor to make use of idle time for calculations
in other parts of the program being run, thus increasing the effective
speed. A variation on this technique is “parallel processing,” in
which multiple processors are linked. If each of, for example, eight
central processors is given a portion of a computing task to perform,
the task will be completed more quickly than the traditional von
Neumann architecture, with its single processor, would allow.
Ever the pragmatist, however, Cray decided to employ proved
technology rather than use advanced techniques in his first supercomputer,
the Cray 1, which was introduced in 1976. Although the
Cray 1 did incorporate vector processing, Cray used a simple form
of vector calculation that made the technique practical and easy to
use. Most striking about this computer was its shape, which was far
more modern than its internal design. The Cray 1 was shaped like a

Seymour R. Cray
Supercomputer / 711
Seymour R. Cray was born in 1928 in Chippewa Falls, Wisconsin.
The son of a civil engineer, he became interested in radio
and electronics as a boy. After graduating from high school in
1943, he joined the U.S. Army, was posted to Europe in an infantry
communications platoon, and fought in the Battle of the
Bulge. Back from the war, he pursued his interest in electronics
in college while majoring in mathematics at the University of
Minnesota. Upon graduation in 1950, he took a job at Engineering
Research Associates. It was there that he first learned
about computers. In fact, he helped design the first digital computer,
UNIVAC.
Cray co-founded Control Data Corporation in 1957. Based
on his ideas, the company built large-scale, high-speed computers.
In 1972 he founded his own company, Cray Research Incorporated,
with the intention of employing new processing methods
and simplifying architecture and software to build the
world’s fastest computers. He succeeded, and the series of computers
that the company marketed made possible computer
modeling as a central part of scientific research in areas as diverse
as meteorology, oil exploration, and nuclear weapons design.
Through the 1970’s and 1980’s Cray Research was at the
forefront of supercomputer technology, which became one of
the symbols of American technological leadership.
In 1989 Cray left Cray Research to form still another company,
Cray Computer Corporation. He planned to build the
next generation supercomputer, the Cray 5, but advances in microprocessor
technology undercut the demand for supercomputers.
Cray Computer entered bankruptcy in 1995. Ayear later
he died from injuries sustained in an automobile accident near
Colorado Springs, Colorado.
cylinder with a small section missing and a hollow center, with
what appeared to be a bench surrounding it. The shape of the machine
was designed to minimize the length of the interconnecting
wires that ran between circuit boards to allow electricity to move the
shortest possible distance. The bench concealed an important part
of the cooling system that kept the system at an appropriate operating
temperature.

712 / Supercomputer
The measurements that describe the performance of supercomputers
are called MIPS (millions of instructions per second) for scalar
processors and megaflops (millions of floating-point operations per
second) for vector processors. (Floating-point numbers are numbers
expressed in scientific notation; for example, 10 27 .) Whereas the fastest
computer before the Cray 1 was capable of some 35 MIPS, the
Cray 1 was capable of 80 MIPS. Moreover, the Cray 1 was theoretically
capable of vector processing at the rate of 160 megaflops, a rate
unheard of at the time.
Consequences
Seymour Cray first estimated that there would be few buyers for
a machine as advanced as the Cray 1, but his estimate turned out to
be incorrect. There were many scientists who wanted to perform
computer modeling (in which scientific ideas are expressed in such
a way that computer-based experiments can be conducted) and
who needed raw processing power.
When dealing with natural phenomena such as the weather or
geological structures, or in rocket design, researchers need to make
calculations involving large amounts of data. Before computers,
advanced experimental modeling was simply not possible, since
even the modest calculations for the development of atomic energy,
for example, consumed days and weeks of scientists’ time.
With the advent of supercomputers, however, large-scale computation
of vast amounts of information became possible. Weather
researchers can design a detailed program that allows them to analyze
complex and seemingly unpredictable weather events such
as hurricanes; geologists searching for oil fields can gather data
about successful finds to help identify new ones; and spacecraft
designers can “describe” in computer terms experimental ideas
that are too costly or too dangerous to carry out. As supercomputer
performance evolves, there is little doubt that scientists will
make ever greater use of its power.
See also Apple II computer; BINAC computer; Colossus computer;
ENIAC computer; IBM Model 1401 computer; Personal computer;
UNIVAC computer.

Further Reading
Supercomputer / 713
Edwards, Owen. “Seymour Cray.” Forbes 154, no. 5 (August 29,
1994).
Lloyd, Therese, and Stanley N. Wellborn. “Computers’ Next Frontiers.”
U.S. News & World Report 99 (August 26, 1985).
Slater, Robert. Portraits in Silicon. Cambridge, Mass.: MIT Press,
1987.
Zipper, Stuart. “Chief Exec. Leaves Cray Computer.” Electronic
News 38, no. 1908 (April, 1992).

714
Supersonic passenger plane
Supersonic passenger plane
The invention: The first commercial airliner that flies passengers at
speeds in excess of the speed of sound.
The people behind the invention:
Sir Archibald Russell (1904- ), a designer with the British
Aircraft Corporation
Pierre Satre (1909- ), technical director at Sud-Aviation
Julian Amery (1919- ), British minister of aviation, 1962-1964
Geoffroy de Cource (1912- ), French minister of aviation,
1962
William T. Coleman, Jr. (1920- ), U.S. secretary of
transportation, 1975-1977
Birth of Supersonic Transportations
On January 21, 1976, the Anglo-French Concorde became the
world’s first supersonic airliner to carry passengers on scheduled
commercial flights. British Airways flew a Concorde from London’s
Heathrow Airport to the Persian Gulf emirate of Bahrain in
three hours and thirty-eight minutes. At about the same time, Air
France flew a Concorde from Paris’s Charles de Gaulle Airport to
Rio de Janeiro, Brazil, in seven hours and twenty-five minutes.
The Concordes’ cruising speeds were about twice the speed of
sound, or 1,350 miles per hour. On May 24, 1976, the United States
and Europe became linked for the first time with commercial supersonic
air transportation. British Airways inaugurated flights
between Dulles International Airport in Washington, D.C., and
Heathrow Airport. Likewise, Air France inaugurated flights between
Dulles International Airport and Charles de Gaulle Airport.
The London-Washington, D.C., flight was flown in an unprecedented
time of three hours and forty minutes. The Paris-
Washington, D.C., flight was flown in a time of three hours and
fifty-five minutes.

The Decision to Build the SST
Supersonic passenger plane / 715
Events leading to the development and production of the Anglo-
French Concorde went back almost twenty years and included approximately
$3 billion in investment costs. Issues surrounding the
development and final production of the supersonic transport (SST)
were extremely complex and at times highly emotional. The concept
of developing an SST brought with it environmental concerns
and questions, safety issues both in the air and on the ground, political
intrigue of international proportions, and enormous economic
problems from costs of operations, research, and development.
In England, the decision to begin the SST project was made in October,
1956. Under the promotion of Morien Morgan with the Royal
Aircraft Establishment in Farnborough, England, it was decided at
the Aviation Ministry headquarters in London to begin development
of a supersonic aircraft. This decision was based on the intense competition
from the American Boeing 707 and Douglas DC-8 subsonic
jets going into commercial service. There was little point in developing
another subsonic plane; the alternative was to go above the speed
of sound. In November, 1956, at Farnborough, the first meeting of the
Supersonic Transport Aircraft Committee, known as STAC, was held.
Members of the STAC proposed that development costs would be
in the range of $165 million to $260 million, depending on the range,
speed, and payload of the chosen SST. The committee also projected
that by 1970, there would be a world market for at least 150 to 500 supersonic
planes. Estimates were that the supersonic plane would recover
its entire research and development cost through thirty sales.
The British, in order to continue development of an SST, needed a European
partner as a way of sharing the costs and preempting objections
to proposed funding by England’s Treasury.
In 1960, the British government gave the newly organized British
Aircraft Corporation (BAC) $1 million for an SST feasibility study.
Sir Archibald Russell, BAC’s chief supersonic designer, visited Pierre
Satre, the technical director at the French firm of Sud-Aviation.
Satre’s suggestion was to evolve an SST from Sud-Aviation’s highly
successful subsonic Caravelle transport. By September, 1962, an
agreement was reached by Sud and BAC design teams on a new
SST, the Super Caravelle.

716 / Supersonic passenger plane
There was a bitter battle over the choice of engines with two British
engine firms, Bristol-Siddeley and Rolls-Royce, as contenders.
Sir Arnold Hall, the managing director of Bristol-Siddeley, in collaboration
with the French aero-engine company SNECMA, was eventually
awarded the contract for the engines. The engine chosen was
a “civilianized” version of the Olympus, which Bristol had been developing
for the multirole TRS-2 combat plane.
The Concorde Consortium
On November 29, 1962, the Concorde Consortium was created
by an agreement between England and the French Republic, signed
by Ministers of Aviation Julian Amery and Geoffroy de Cource
(1912- ). The first Concorde, Model 001, rolled out from Sud-
Aviation’s St. Martin-du-Touch assembly plant on December 11,
1968. The second, Model 002, was completed at the British Aircraft
Corporation a few months later. Eight years later, on January 21,
1976, the Concorde became the world’s first supersonic airliner to
carry passengers on scheduled commercial flights.
Development of the SST did not come easily for the Anglo-
French consortium. The nature of supersonic flight created numerous
problems and uncertainties not present for subsonic flight. The
SST traveled faster than the speed of sound. Sound travels at 760
miles per hour at sea level at a temperature of 59 degrees Fahrenheit.
This speed drops to about 660 miles per hour at sixty-five thousand
feet, cruising altitude for the SST, where the air temperature
drops to 70 degrees below zero.
The Concorde was designed to fly at a maximum of 1,450 miles
per hour. The European designers could use an aluminum alloy
construction and stay below the critical skin-friction temperatures
that required other airframe alloys, such as titanium. The Concorde
was designed with a slender curved wing surface. The design incorporated
widely separated engine nacelles, each housing two Olympus
593 jet engines. The Concorde was also designed with a “droop
snoot,” providing three positions: the supersonic configuration, a
heat-visor retracted position for subsonic flight, and a nose-lowered
position for landing patterns.

Impact
Supersonic passenger plane / 717
Early SST designers were faced with questions such as the intensity
and ionization effect of cosmic rays at flight altitudes of sixty to
seventy thousand feet. The “cascade effect” concerned the intensification
of cosmic radiation when particles from outer space struck a
metallic cover. Scientists looked for ways to shield passengers from
this hazard inside the aluminum or titanium shell of an SST flying
high above the protective blanket of the troposphere. Experts questioned
whether the risk of being struck by meteorites was any
greater for the SST than for subsonic jets and looked for evidence on
wind shear of jet streams in the stratosphere.
Other questions concerned the strength and frequency of clear air
turbulence above forty-five thousand feet, whether the higher ozone
content of the air at SST cruise altitude would affect the materials of
the aircraft, whether SST flights would upset or destroy the protective
nature of the earth’s ozone layer, the effect of aerodynamic heating
on material strength, and the tolerable strength of sonic booms
over populated areas. These and other questions consumed the designers
and researchers involved in developing the Concorde.
Through design research and flight tests, many of the questions
were resolved or realized to be less significant than anticipated. Several
issues did develop into environmental, economic, and international
issues. In late 1975, the British and French governments requested
permission to use the Concorde at New York’s John F.
Kennedy International Airport and at Dulles International Airport
for scheduled flights between the United States and Europe. In December,
1975, as a result of strong opposition from anti-Concorde
environmental groups, the U.S. House of Representatives approved
a six-month ban on SSTs coming into the United States so that the
impact of flights could be studied. Secretary of Transportation William
T. Coleman, Jr., held hearings to prepare for a decision by February
5, 1976, as to whether to allow the Concorde into U.S. airspace.
The British and French, if denied landing rights, threatened
to take the United States to an international court, claiming that
treaties had been violated.
The treaties in question were the Chicago Convention and Bermuda
agreements of February 11, 1946, and March 27, 1946. These

718 / Supersonic passenger plane
treaties prohibited the United States from banning aircraft that both
France and Great Britain had certified to be safe. The Environmental
Defense Fund contended that the United States had the right to ban
SST aircraft on environmental grounds.
Under pressure from both sides, Coleman decided to allow limited
Concorde service at Dulles and John F. Kennedy airports for a
sixteen-month trial period. Service into John F. Kennedy Airport,
however, was delayed by a ban by the Port Authority of New York
and New Jersey until a pending suit was pursued by the airlines.
During the test period, detailed records were to be kept on the
Concorde’s noise levels, vibration, and engine emission levels. Other
provisions included that the plane would not fly at supersonic
speeds over the continental United States; that all flights could be
cancelled by the United States with four months notice, or immediately
if they proved harmful to the health and safety of Americans;
and that at the end of a year, four months of study would begin to
determine if the trial period should be extended.
The Concorde’s noise was one of the primary issues in determining
whether the plane should be allowed into U.S. airports. The Federal
Aviation Administration measured the effective perceived noise
in decibels. After three months of monitoring the Concorde’s departure
noise at 3.5 nautical miles was found to vary from 105 to 130
decibels. The Concorde’s approach noise at one nautical mile from
threshold varied from 115 to 130 decibels. These readings were approximately
equal to noise levels of other four-engine jets, such as
the Boeing 747, on landing but were twice as loud on takeoff.
The Economics of Operation
Another issue of significance was the economics of Concorde’s
operation and its tremendous investment costs. In 1956, early predictions
of Great Britain’s STAC were for a world market of 150 to
500 supersonic planes. In November, 1976, Great Britain’s Gerald
Kaufman and France’s Marcel Cavaille said that production of the
Concorde would not continue beyond the sixteen vehicles then contracted
for with BAC and Sud-Aviation. There was no demand by
U.S. airline corporations for the plane. Given that the planes could
not fly at supersonic speeds over populated areas because of the

sonic boom phenomenon, markets for the SST had to be separated
by at least three thousand miles, with flight paths over mostly water
or desert. Studies indicated that there were only twelve to fifteen
routes in the world for which the Concorde was suitable. The planes
were expensive, at a price of approximately $74 million each and
had a limited seating capacity of one hundred passengers. The
plane’s range was about four thousand miles.
These statistics compared to a Boeing 747 with a cost of $35 million,
seating capacity of 360, and a range of six thousand miles. In
addition, the International Air Transport Association negotiated
that the fares for the Concorde flights should be equivalent to current
first-class fares plus 20 percent. The marketing promotion for
the Anglo-French Concorde was thus limited to the elite business
traveler who considered speed over cost of transportation. Given
these factors, the recovery of research and development costs for
Great Britain and France would never occur.
See also Airplane; Bullet train; Dirigible; Rocket; Stealth aircraft;
Turbojet; V-2 rocket.
Further Reading
Supersonic passenger plane / 719
Ellingsworth, Rosalind K. “Concorde Stresses Time, Service.” Aviation
Week and Space Technology 105 (August 16, 1976).
Kozicharow, Eugene. “Concorde Legal Questions Raised.” Aviation
Week and Space Technology 104 (January 12, 1976).
Ropelewski, Robert. “Air France Poised for Concorde Service.” Aviation
Week and Space Technology 104 (January 19, 1976).
Sparaco, Pierre. “Official Optimism Grows for Concorde’s Return.”
Aviation Week and Space Technology 154, no. 8 (February 19, 2001).
Trubshaw, Brian. Concorde: The Inside Story. Thrupp, Stroud: Sutton,
2000.

720
Synchrocyclotron
Synchrocyclotron
The invention: A powerful particle accelerator that performed
better than its predecessor, the cyclotron.
The people behind the invention:
Edwin Mattison McMillan (1907-1991), an American physicist
who won the Nobel Prize in Chemistry in 1951
Vladimir Iosifovich Veksler (1907-1966), a Soviet physicist
Ernest Orlando Lawrence (1901-1958), an American physicist
Hans Albrecht Bethe (1906- ), a German American physicist
The First Cyclotron
The synchrocyclotron is a large electromagnetic apparatus designed
to accelerate atomic and subatomic particles at high energies.
Therefore, it falls under the broad class of scientific devices
known as “particle accelerators.” By the early 1920’s, the experimental
work of physicists such as Ernest Rutherford and George
Gamow demanded that an artificial means be developed to generate
streams of atomic and subatomic particles at energies much
greater than those occurring naturally. This requirement led Ernest
Orlando Lawrence to develop the cyclotron, the prototype for most
modern accelerators. The synchrocyclotron was developed in response
to the limitations of the early cyclotron.
In September, 1930, Lawrence announced the basic principles behind
the cyclotron. Ionized—that is, electrically charged—particles
are admitted into the central section of a circular metal drum. Once
inside the drum, the particles are exposed to an electric field alternating
within a constant magnetic field. The combined action of the
electric and magnetic fields accelerates the particles into a circular
path, or orbit. This increases the particles’ energy and orbital radii.
This process continues until the particles reach the desired energy
and velocity and are extracted from the machine for use in experiments
ranging from particle-to-particle collisions to the synthesis of
radioactive elements.

Although Lawrence was interested in the practical applications
of his invention in medicine and biology, the cyclotron also was applied
to a variety of experiments in a subfield of physics called
“high-energy physics.” Among the earliest applications were studies
of the subatomic, or nuclear, structure of matter. The energetic
particles generated by the cyclotron made possible the very type of
experiment that Rutherford and Gamow had attempted earlier.
These experiments, which bombarded lithium targets with streams
of highly energetic accelerated protons, attempted to probe the inner
structure of matter.
Although funding for scientific research on a large scale was
scarce before World War II (1939-1945), Lawrence nevertheless conceived
of a 467-centimeter cyclotron that would generate particles
with energies approaching 100 million electronvolts. By the end of
the war, increases in the public and private funding of scientific research
and a demand for higher-energy particles created a situation
in which this plan looked as if it would become reality, were it not
for an inherent limit in the physics of cyclotron operation.
Overcoming the Problem of Mass
Synchrocyclotron / 721
In 1937, Hans Albrecht Bethe discovered a severe theoretical limitation
to the energies that could be produced in a cyclotron. Physicist
Albert Einstein’s special theory of relativity had demonstrated
that as any mass particle gains velocity relative to the speed of light,
its mass increases. Bethe showed that this increase in mass would
eventually slow the rotation of each particle. Therefore, as the rotation
of each particle slows and the frequency of the alternating electric
field remains constant, particle velocity will decrease eventually.
This factor set an upper limit on the energies that any cyclotron
could produce.
Edwin Mattison McMillan, a colleague of Lawrence at Berkeley,
proposed a solution to Bethe’s problem in 1945. Simultaneously and
independently, Vladimir Iosifovich Veksler of the Soviet Union proposed
the same solution. They suggested that the frequency of the
alternating electric field be slowed to meet the decreasing rotational
frequencies of the accelerating particles—in essence, “synchroniz-

722 / Synchrocyclotron
ing” the electric field with the moving particles. The result was the
synchrocyclotron.
Prior to World War II, Lawrence and his colleagues had obtained
the massive electromagnet for the new 100-million-electronvolt cyclotron.
This 467-centimeter magnet would become the heart of the
new Berkeley synchrocyclotron. After initial tests proved successful,
the Berkeley team decided that it would be reasonable to convert
the cyclotron magnet for use in a new synchrocyclotron. The
apparatus was operational in November of 1946.
These high energies combined with economic factors to make the
synchrocyclotron a major achievement for the Berkeley Radiation
Laboratory. The synchrocyclotron required less voltage to produce
higher energies than the cyclotron because the obstacles cited by
Bethe were virtually nonexistent. In essence, the energies produced
by synchrocyclotrons are limited only by the economics of building
them. These factors led to the planning and construction of other
synchrocyclotrons in the United States and Europe. In 1957, the
Berkeley apparatus was redesigned in order to achieve energies of
720 million electronvolts, at that time the record for cyclotrons of
any kind.
Impact
Previously, scientists had had to rely on natural sources for highly
energetic subatomic and atomic particles with which to experiment.
In the mid-1920’s, the American physicist Robert Andrews Millikan
began his experimental work in cosmic rays, which are one natural
source of energetic particles called “mesons.” Mesons are charged
particles that have a mass more than two hundred times that of the
electron and are therefore of great benefit in high-energy physics experiments.
In February of 1949, McMillan announced the first synthetically
produced mesons using the synchrocyclotron.
McMillan’s theoretical development led not only to the development
of the synchrocyclotron but also to the development of the
electron synchrotron, the proton synchrotron, the microtron, and
the linear accelerator. Both proton and electron synchrotrons have
been used successfully to produce precise beams of muons and pimesons,
or pions (a type of meson).

The increased use of accelerator apparatus ushered in a new era
of physics research, which has become dominated increasingly by
large accelerators and, subsequently, larger teams of scientists and
engineers required to run individual experiments. More sophisticated
machines have generated energies in excess of 2 trillion
electronvolts at the United States’ Fermi National Accelerator Laboratory,
or Fermilab, in Illinois. Part of the huge Tevatron apparatus
at Fermilab, which generates these particles, is a proton synchrotron,
a direct descendant of McMillan and Lawrence’s early
efforts.
See also Atomic bomb; Cyclotron; Electron microscope; Field ion
microscope; Geiger counter; Hydrogen bomb; Mass spectrograph;
Neutrino detector; Scanning tunneling microscope; Tevatron accelerator.
Further Reading
Synchrocyclotron / 723
Bernstein, Jeremy. Hans Bethe: Prophet of Energy. New York: Basic
Books, 1980.
McMillan, Edwin. “The Synchrotron: A Proposed High-Energy Particle
Accelerator.” Physical Review 68 (September, 1945).
_____. “Vladimir Iosifovich Veksler.” Physics Today (November,
1966).
“Witness to a Century.” Discover 20 (December, 1999).

724
Synthetic amino acid
Synthetic amino acid
The invention: A method for synthesizing amino acids by combining
water, hydrogen, methane, and ammonia and exposing the
mixture to an electric spark.
The people behind the invention:
Stanley Lloyd Miller (1930- ), an American professor of
chemistry
Harold Clayton Urey (1893-1981), an American chemist who
won the 1934 Nobel Prize in Chemistry
Aleksandr Ivanovich Oparin (1894-1980), a Russian biochemist
John Burdon Sanderson Haldane (1892-1964), a British scientist
Prebiological Evolution
The origin of life on Earth has long been a tough problem for scientists
to solve. While most scientists can envision the development
of life through geologic time from simple single-cell bacteria
to complex mammals by the processes of mutation and natural selection,
they have found it difficult to develop a theory to define
how organic materials were first formed and organized into lifeforms.
This stage in the development of life before biologic systems
arose, which is called “chemical evolution,” occurred between
4.5 and 3.5 billion years ago. Although great advances in
genetics and biochemistry have shown the intricate workings of
the cell, relatively little light has been shed on the origins of this intricate
machinery of the cell. Some experiments, however, have
provided important data from which to build a scientific theory of
the origin of life. The first of these experiments was the classic
work of Stanley Lloyd Miller.
Miller worked with Harold Clayton Urey, a Nobel laureate, on the
environments of the early earth. John Burdon Sanderson Haldane, a
British biochemist, had suggested in 1929 that the earth’s early atmosphere
was a reducing one—that it contained no free oxygen. In
1952, Urey published a seminal work in planetology, The Planets,in
which he elaborated on Haldane’s suggestion, and he postulated

that the earth had formed from a cold stellar dust cloud. Urey
thought that the earth’s primordial atmosphere probably contained
elements in the approximate relative abundances found in the solar
system and the universe.
It had been discovered in 1929 that the Sun is approximately 87
percent hydrogen, and by 1935 it was known that hydrogen encompassed
the vast majority (92.8 percent) of atoms in the universe.
Urey reasoned that the earth’s early atmosphere contained mostly
hydrogen, with the oxygen, nitrogen, and carbon atoms chemically
bonded to hydrogen to form water, ammonia, and methane. Most
important, free oxygen could not exist in the presence of such an
abundance of hydrogen.
As early as the mid-1920’s, Aleksandr Ivanovich Oparin, a Russian
biochemist, had argued that the organic compounds necessary
for life had been built up on the early earth by chemical combinations
in a reducing atmosphere. The energy from the Sun would
have been sufficient to drive the reactions to produce life. Haldane
later proposed that the organic compounds would accumulate in
the oceans to produce a “dilute organic soup” and that life might
have arisen by some unknown process from that mixture of organic
compounds.
Primordial Soup in a Bottle
Synthetic amino acid / 725
Miller combined the ideas of Oparin and Urey and designed a
simple, but elegant, experiment. He decided to mix the gases presumed
to exist in the early atmosphere (water vapor, hydrogen, ammonia,
and methane) and expose them to an electrical spark to determine
which, if any, organic compounds were formed. To do this,
he constructed a relatively simple system, essentially consisting of
two Pyrex flasks connected by tubing in a roughly circular pattern.
The water and gases in the smaller flask were boiled and the resulting
gas forced through the tubing into a larger flask that contained
tungsten electrodes. As the gases passed the electrodes, an electrical
spark was generated, and from this larger flask the gases and any
other compounds were condensed. The gases were recycled through
the system, whereas the organic compounds were trapped in the
bottom of the system.

726 / Synthetic amino acid
Miller was trying to simulate conditions that had prevailed on
the early earth. During the one week of operation, Miller extracted
and analyzed the residue of compounds at the bottom of the system.
The results were truly astounding. He found that numerous organic
compounds had, indeed, been formed in only that one week. As
much as 15 percent of the carbon (originally in the gas methane) had
been combined into organic compounds, and at least 5 percent of
the carbon was incorporated into biochemically important compounds.
The most important compounds produced were some of
the twenty amino acids essential to life on Earth.
The formation of amino acids is significant because they are the
building blocks of proteins. Proteins consist of a specific sequence of
amino acids assembled into a well-defined pattern. Proteins are necessary
for life for two reasons. First, they are important structural
Water in
Vacuum
Boiling Water
Water Vapor
Electrode
Nh3
CH4
The Miller-Urey experiment.
H2
Condenser
Cooled Water
Containing
Organic Compounds
Sample for
Chemical Analysis

materials used to build the cells of the body. Second, the enzymes
that increase the rate of the multitude of biochemical reactions of life
are also proteins. Miller not only had produced proteins in the laboratory
but also had shown clearly that the precursors of proteins—
the amino acids—were easily formed in a reducing environment
with the appropriate energy.
Perhaps the most important aspect of the experiment was the
ease with which the amino acids were formed. Of all the thousands
of organic compounds that are known to chemists, amino acids
were among those that were formed by this simple experiment. This
strongly implied that one of the first steps in chemical evolution was
not only possible but also highly probable. All that was necessary
for the synthesis of amino acids were the common gases of the solar
system, a reducing environment, and an appropriate energy source,
all of which were present on early Earth.
Consequences
Synthetic amino acid / 727
Miller opened an entirely new field of research with his pioneering
experiments. His results showed that much about chemical
evolution could be learned by experimentation in the laboratory.
As a result, Miller and many others soon tried variations on
his original experiment by altering the combination of gases, using
other gases, and trying other types of energy sources. Almost all
the essential amino acids have been produced in these laboratory
experiments.
Miller’s work was based on the presumed composition of the
primordial atmosphere of Earth. The composition of this atmosphere
was calculated on the basis of the abundance of elements
in the universe. If this reasoning is correct, then it is highly likely
that there are many other bodies in the universe that have similar
atmospheres and are near energy sources similar to the Sun.
Moreover, Miller’s experiment strongly suggests that amino acids,
and perhaps life as well, should have formed on other planets.
See also Artificial hormone; Artificial kidney; Synthetic DNA;
Synthetic RNA.

728 / Synthetic amino acid
Further Reading
Dronamraju, Krishna R., and J. B. S. Haldane. Haldane’s Daedalus Revisited.
New York: Oxford University Press, 1995.
Lipkin, Richard. “Early Earth May Have Had Two Key RNA Bases.”
Science News 148, no. 1 (July 1, 1995).
Miller, Stanley L., and Leslie E. Orgel. The Origins of Life on the Earth.
Englewood Cliffs, N.J.: Prentice-Hall, 1974.
Nelson, Kevin E., Matthew Levy, and Stanley L. Miller. “Peptide
Nucleic Acids Rather than RNA May Have Been the First Genetic
Molecule.” Proceedings of the National Academy of Sciences of the
United States of America 97, no. 8 (April 11, 2000).
Yockey, Hubert P. “Walther Lob, Stanley L. Miller, and Prebiotic
‘Building Blocks’ in the Silent Electrical Discharge.” Perspectives
in Biology and Medicine 41, no. 1 (Autumn, 1997).

Synthetic DNA
Synthetic DNA
The invention: A method for replicating viral deoxyribonucleic
acid (DNA) in a test tube that paved the way for genetic engineering.
The people behind the invention:
Arthur Kornberg (1918- ), an American physician and
biochemist
Robert L. Sinsheimer (1920- ), an American biophysicist
Mehran Goulian (1929- ), a physician and biochemist
The Role of DNA
729
Until the mid-1940’s, it was believed that proteins were the
carriers of genetic information, the source of heredity. Proteins
appeared to be the only biological molecules that had the complexity
necessary to encode the enormous amount of genetic information
required to reproduce even the simplest organism.
Nevertheless, proteins could not be shown to have genetic properties,
and by 1944, it was demonstrated conclusively that deoxyribonucleic
acid (DNA) was the material that transmitted hereditary
information. It was discovered that DNA isolated from a
strain of infective bacteria that can cause pneumonia was able to
transform a strain of noninfective bacteria into an infective strain;
in addition, the infectivity trait was transmitted to future generations.
Subsequently, it was established that DNA is the genetic material
in virtually all forms of life.
Once DNA was known to be the transmitter of genetic information,
scientists sought to discover how it performs its role. DNA is a
polymeric molecule composed of four different units, called “deoxynucleotides.”
The units consist of a sugar, a phosphate group, and a
base; they differ only in the nature of the base, which is always one of
four related compounds: adenine, guanine, cytosine, or thymine. The
way in which such a polymer could transmit genetic information,
however, was difficult to discern. In 1953, biophysicists James D. Watson
and Francis Crick brilliantly determined the three-dimensional

730 / Synthetic DNA
structure of DNA by analyzing X-ray diffraction photographs of DNA
fibers. From their analysis of the structure of DNA, Watson and Crick
inferred DNA’s mechanism of replication. Their work led to an understanding
of gene function in molecular terms.
Watson and Crick showed that DNA has a very long doublestranded
(duplex) helical structure. DNA has a duplex structure because
each base forms a link to a specific base on the opposite
strand. The discovery of this complementary pairing of bases provided
a model to explain the two essential functions of a hereditary
molecule: It must preserve the genetic code from one generation to
the next, and it must direct the development of the cell.
Watson and Crick also proposed that DNA is able to serve as a
mold (or template) for its own reproduction because the two strands
of DNA polymer can separate. Upon separation, each strand acts as a
template for the formation of a new complementary strand. An adenine
base in the existing strand gives rise to cytosine, and so on. In
this manner, a new double-stranded DNA is generated that is identical
to the parent DNA.
DNA in a Test Tube
Watson and Crick’s theory provided a valuable model for the reproduction
of DNA, but it did not explain the biological mechanism
by which the process occurs. The biochemical pathway of DNA reproduction
and the role of the enzymes required for catalyzing the
reproduction process were discovered by Arthur Kornberg and his
coworkers. For his success in achieving DNA synthesis in a test tube
and for discovering and isolating an enzyme—DNA polymerase—
that catalyzed DNA synthesis, Kornberg won the 1959 Nobel Prize
in Physiology or Medicine.
To achieve DNA replication in a test tube, Kornberg found that a
small amount of preformed DNA must be present, in addition to
DNA polymerase enzyme and all four of the deoxynucleotides that
occur in DNA. Kornberg discovered that the base composition of
the newly made DNA was determined solely by the base composition
of the preformed DNA, which had been used as a template in
the test-tube synthesis. This result showed that DNA polymerase
obeys instructions dictated by the template DNA. It is thus said to

e “template-directed.” DNA polymerase was the first templatedirected
enzyme to be discovered.
Although test-tube synthesis was a most significant achievement,
important questions about the precise character of the newly
made DNA were still unanswered. Methods of analyzing the order,
or sequence, of the bases in DNA were not available, and hence it
could not be shown directly whether DNAmade in the test tube was
an exact copy of the template of DNA or merely an approximate
copy. In addition, some DNAs prepared by DNA polymerase appeared
to be branched structures. Since chromosomes in living cells
contain long, linear, unbranched strands of DNA, this branching
might have indicated that DNA synthesized in a test tube was not
equivalent to DNA synthesized in the living cell.
Kornberg realized that the best way to demonstrate that newly
synthesized DNA is an exact copy of the original was to test the new
DNA for biological activity in a suitable system. Kornberg reasoned
that a demonstration of infectivity in viral DNA produced in a test
tube would prove that polymerase-catalyzed synthesis was virtually
error-free and equivalent to natural, biological synthesis. The
experiment, carried out by Kornberg, Mehran Goulian at Stanford
University, and Robert L. Sinsheimer at the California Institute of
Technology, was a complete success. The viral DNAs produced in a
test tube by the DNA polymerase enzyme, using a viral DNA template,
were fully infective. This synthesis showed that DNA polymerase
could copy not merely a single gene but also an entire chromosome
of a small virus without error.
Consequences
Synthetic DNA / 731
The purification of DNA polymerase and the preparation of biologically
active DNA were major achievements that influenced
biological research on DNA for decades. Kornberg’s methodology
proved to be invaluable in the discovery of other enzymes that synthesize
DNA. These enzymes have been isolated from Escherichia
coli bacteria and from other bacteria, viruses, and higher organisms.
The test-tube preparation of viral DNA also had significance in
the studies of genes and chromosomes. In the mid-1960’s, it had not
been established that a chromosome contains a continuous strand of

732 / Synthetic DNA
DNA. Kornberg and Sinsheimer’s synthesis of a viral chromosome
proved that it was, indeed, a very long strand of uninterrupted
DNA.
Kornberg and Sinsheimer’s work laid the foundation for subsequent
recombinant DNA research and for genetic engineering technology.
This technology promises to revolutionize both medicine
and agriculture. The enhancement of food production and the generation
of new drugs and therapies are only a few of the subsequent
benefits that may be expected.
See also Artificial chromosome; Artificial hormone; Cloning; Genetic
“fingerprinting”; Genetically engineered insulin; In vitro plant
culture; Synthetic amino acid; Synthetic RNA.
Further Reading
Baker, Tania A., and Arthur Kornberg. DNA Replication. 2d ed. New
York: W. H. Freeman, 1991.
Kornberg, Arthur. The Golden Helix: Inside Biotech Ventures. Sausalito,
Calif.: University Science Books, 1995.
_____. For the Love of Enzymes: The Odyssey of a Biochemist. Harvard
University Press, 1991.
Sinsheimer, Robert. The Strands of a Life: The Science of DNA and the
Art of Education. Berkeley: University of California Press, 1994.

Synthetic RNA
Synthetic RNA
The invention: A method for synthesizing the biological molecule
RNA established that this process can occur outside the living
cell.
The people behind the invention:
Severo Ochoa (1905-1993), a Spanish biochemist who shared
the 1959 Nobel Prize in Physiology or Medicine
Marianne Grunberg-Manago (1921- ), a French biochemist
Marshall W. Nirenberg (1927- ), an American biochemist
who won the 1968 Nobel Prize in Physiology or Medicine
Peter Lengyel (1929- ), a Hungarian American biochemist
RNA Outside the Cells
733
In the early decades of the twentieth century, genetics had not
been experimentally united with biochemistry. This merging soon
occurred, however, with work involving the mold Neurospora crassa.
This Nobel award-winning work by biochemist Edward Lawrie
Tatum and geneticist George Wells Beadle showed that genes control
production of proteins, which are major functional molecules in
cells. Yet no one knew the chemical composition of genes and chromosomes,
or, rather, the molecules of heredity.
The American bacteriologist Oswald T. Avery and his colleagues
at New York’s Rockefeller Institute determined experimentally that
the molecular basis of heredity was a large polymer known as deoxyribonucleic
acid (DNA). Avery’s discovery triggered a furious
worldwide search for the particular structural characteristics of
DNA, which allow for the known biological characteristics of genes.
One of the most famous studies in the history of science solved
this problem in 1953. Scientists James D. Watson, Francis Crick, and
Maurice H. F. Wilkins postulated that DNA exists as a double helix.
That is, two long strands twist about each other in a predictable pattern,
with each single strand held to the other by weak, reversible
linkages known as “hydrogen bonds.” About this time, researchers
recognized also that a molecule closely related to DNA, ribonucleic

734 / Synthetic RNA
acid (RNA), plays an important role in transcribing the genetic information
as well as in other biological functions.
Severo Ochoa was born in Spain as the science of genetics was
developing. In 1942, he moved to New York University, where he
studied the bacterium Azobacter vinelandii. Specifically, Ochoa was
focusing on the question of how cells process energy in the form of
organic molecules such as the sugar glucose to provide usable biological
energy in the form of adenosine triphosphate (ATP). With
postdoctoral fellow Marianne Grunberg-Manago, he studied enzymatic
reactions capable of incorporating inorganic phosphate (a
compound consisting of one atom of phosphorus and four atoms of
oxygen) into adenosine diphosphate (ADP) to form ATP.
One particularly interesting reaction was followed by monitoring
the amount of radioactive phosphate reacting with ADP. Following
separation of the reaction products, it was discovered that
the main product was not ATP, but a much larger molecule. Chemical
characterization demonstrated that this product was a polymer
of adenosine monophosphate. When other nucleocide diphosphates,
such as inosine diphosphate, were used in the reaction, the
corresponding polymer of inosine monophosphate was formed.
Thus, in each case, a polymer (a long string of building-block
units) was formed. The polymers formed were synthetic RNAs, and
the enzyme responsible for the conversion became known as “polynucleotide
phosphorylase.” This finding, once the early skepticism
was resolved, was received by biochemists with great enthusiasm
because no technique outside the cell had ever been discovered
previously in which a nucleic acid similar to RNA could be
synthesized.
Learning the Language
Ochoa, Peter Lengyel, and Marshall W. Nirenberg at the National
Institute of Health took advantage of this breakthrough to synthesize
different RNAs useful in cracking the genetic code. Crick had
postulated that the flow of information in biological systems is from
DNA to RNA to protein. In other words, genetic information contained
in the DNA structure is transcribed into complementary
RNA structures, which, in turn, are translated into the protein. Pro-

tein synthesis, an extremely complex process, involves bringing a
type of RNA, known as messenger RNA, together with amino acids
and huge cellular organelles known as ribosomes.
Yet investigators did not know the nature of the nucleic acid alphabet—for
example, how many single units of the RNA polymer
code were needed for each amino acid, and the order that the units
must be in to stand for a “word” in the nucleic acid language. In
1961, Nirenberg demonstrated that the polymer of synthetic RNA
with multiple units of uracil (poly U) would “code” only for a protein
containing the amino acid phenylalanine. Each three units (U’s)
gave one phenylalanine. Therefore, genetic words each contain
three letters. UUU translates into phenylalanine. Poly A, the first
polymer discovered with polynucleotide phosphorylase, was coded
for a protein containing multiple lysines. That is, AAA translates
into the amino acid lysine.
The words, containing combinations of letters, such as AUG, were
not as easily studied, but Nirenberg, Ochoa, and Gobind Khorana of
the University of Wisconsin eventually uncovered the exact translation
for each amino acid. In RNA, there are four possible letters (A, U,
G, and C) and three letters in each word. Accordingly, there are sixtyfour
possible words. With only twenty amino acids, it became clear
that more than one RNA word can translate into a given amino acid.
Yet, no given word stands for any more than one amino acid. A few
words do not translate into any amino acid; they are stop signals, telling
the ribosome to cease translating RNA.
The question of which direction an RNA is translated is critical.
For example, CAA codes for the amino acid glutamine, but the reverse,
AAC, translates to the amino acid asparagine. Such a difference
is critical because the exact sequence of a protein determines its
activity—that is, what it will do in the body and therefore what genetic
trait it will express.
Consequences
Synthetic RNA / 735
Synthetic RNAs provided the key to understanding the genetic
code. The genetic code is universal; it operates in all organisms, simple
or complex. It is used by viruses, which are nearly life but are not
alive. Spelling out the genetic code was one of the top discoveries of

736 / Synthetic RNA
the twentieth century. Nearly all work in molecular biology depends
on this knowledge.
The availability of synthetic RNAs has provided hybridization
tools for molecular geneticists. Hybridization is a technique in which
an RNA is allowed to bind in a complementary fashion to DNA under
investigation. The greater the similarity between RNA and DNA,
the greater the amount of binding. The differential binding allows for
seeking, finding, and ultimately isolating a target DNA from a large,
diverse pool of DNA—in short, finding a needle in a haystack. Hybridization
has become an indispensable aid in experimental molecular
genetics as well as in applied sciences, such as forensics.
See also Artificial chromosome; Artificial hormone; Cloning; Genetic
“fingerprinting”; Genetically engineered insulin; In vitro plant
culture; Synthetic amino acid; Synthetic DNA.
Further Reading
“Biochemist Severo Ochoa Dies: Won Nobel Prize.” Washington Post
(November 3, 1993).
Santesmases, Maria Jesus. “Severo Ochoa and the Biomedical Sciences
in Spain Under Franco, 1959-1975.” Isis 91, no. 4 (December,
2000).
“Severo Ochoa, 1905-1993.” Nature 366, no. 6454 (December, 1993).

Syphilis test
Syphilis test
The invention: The first simple test for detecting the presence of
the venereal disease syphilis led to better syphilis control and
other advances in immunology.
The people behind the invention:
Reuben Leon Kahn (1887-1974), a Soviet-born American
serologist and immunologist
August von Wassermann (1866-1925), a German physician and
bacteriologist
Columbus’s Discoveries
737
Syphilis is one of the chief venereal diseases, a group of diseases
whose name derives from Venus, the Roman goddess of love. The
term “venereal” arose from the idea that the diseases were transmitted
solely by sexual contact with an infected individual. Although
syphilis is almost always passed from one person to another in this
way, it occasionally arises after contact with objects used by infected
people in highly unclean surroundings, particularly in the underdeveloped
countries of the world.
It is believed by many that syphilis was introduced to Europe by
the members of Spanish explorer Christopher Columbus’s crew—
supposedly after they were infected by sexual contact with West Indian
women—during their voyages of exploration. Columbus is reported
to have died of heart and brain problems very similar to
symptoms produced by advanced syphilis. At that time, according
to many historians, syphilis spread rapidly over sixteenth century
Europe. The name “syphilis” was coined by the Italian physician
Girolamo Fracastoro in 1530 in an epic poem he wrote.
Modern syphilis is much milder than the original disease and relatively
uncommon. Yet, if it is not identified and treated appropriately,
syphilis can be devastating and even fatal. It can also be passed from
pregnant mothers to their unborn children. In these cases, the afflicted
children will develop serious health problems that can include
paralysis, insanity, and heart disease. Therefore, the understanding,

738 / Syphilis test
detection, and cure of syphilis are important worldwide.
Syphilis is caused by a spiral-shaped germ called a “spirochete.”
Spirochetes enter the body through breaks in the skin or through the
mucous membranes, regardless of how they are transmitted. Once
spirochetes enter the body, they spread rapidly. During the first four
to six weeks after infection, syphilis—said to be in its primary
phase—is very contagious. During this time, it is identified by the
appearance of a sore, or chancre, at the entry site of the infecting spirochetes.
The chancre disappears quickly, and within six to twenty-four
weeks, the disease shows itself as a skin rash, feelings of malaise,
and other flulike symptoms (secondary-phase syphilis). These problems
also disappear quickly in most cases, and here is where the real
trouble—latent syphilis—begins. In latent syphilis, now totally without
symptoms, spirochetes that have spread through the body may
lodge in the brain or the heart. When this happens, paralysis, mental
incapacitation, and death may follow.
Testing Before Marriage
Because of the danger to unborn children, Americans wishing to
marry must be certified as being free of the disease before a marriage
license is issued. The cure for syphilis is easily accomplished
through the use of penicillin or other types of antibiotics, though no
vaccine is yet available to prevent the disease. It is for this reason
that syphilis detection is particularly important.
The first viable test for syphilis was originated by August von
Wassermann in 1906. In this test, blood samples are taken and
treated in a medical laboratory. The treatment of the samples is
based on the fact that the blood of infected persons has formed antibodies
to fight the syphilis spirochete, and that these antibodies will
react with certain body chemicals to cause the blood sample to clot.
This indicates the person has the disease. After the syphilis has been
cured, the antibodies disappear, as does the clotting.
Although the Wassermann test was effective in 95 percent of all
infected persons, it was very time-consuming (requiring a two-day
incubation period) and complex. In 1923, Reuben Leon Kahn developed
a modified syphilis test, “the standard Kahn test,” that was

simpler and faster: The test was complete after only a few minutes.
By 1925, Kahn’s test had become the standard syphilis test of the
United States Navy and later became a worldwide test for the detection
of the disease.
Kahn soon realized that his test was not perfect and that in some
cases, the results were incorrect. This led him to a broader study of
the immune reactions at the center of the Kahn test. He investigated
the role of various tissues in immunity, as compared to the role of
white blood antibodies and white blood cells. Kahn showed, for example,
that different tissues of immunized or nonimmunized animals
possessed differing immunologic capabilities. Furthermore,
the immunologic capabilities of test animals varied with their
age, being very limited in newborns and increasing as they matured.
This effort led, by 1951, to Kahn’s “universal serological reaction,”
a precipitation reaction in which blood serum was tested
against a reagent composed of tissue lipids. Kahn viewed it as a potentially
helpful chemical indicator of how healthy or ill an individual
was. This effort is viewed as an important landmark in the development
of the science of immunology.
Impact
Syphilis test / 739
At the time that Kahn developed his standard Kahn test for syphilis,
the Wassermann test was used all over the world for the diagnosis
of syphilis. As has been noted, one of the great advantages of the
standard Kahn test was its speed, minutes versus days. For example,
in October, 1923, Kahn is reported to have tested forty serum
samples in fifteen minutes.
Kahn’s efforts have been important to immunology and to medicine.
Among the consequences of his endeavors was the stimulation
of other developments in the field, including the VDRL test (originated
by the Venereal Disease Research Laboratory), which has replaced
the Kahn test as one of the most often used screening tests for
syphilis. Even more specific syphilis tests developed later include a
fluorescent antibody test to detect the presence of the antibody to
the syphilis spirochete.

740 / Syphilis test
See also Abortion pill; Amniocentesis; Antibacterial drugs; Birth
control pill; Mammography; Pap test; Penicillin; Ultrasound.
Further Reading
Cates, William, Jr., Richard B. Rothenberg, and Joseph H. Blount.
“Syphilis Control.” Sexually Transmitted Diseases 23, no. 1 (January,
1996).
Cobb, W. Montague. “Reuben Leon Kahn.” Journal of the National
Medical Association 63 (September, 1971).
Quétel, Claude. History of Syphilis. Baltimore: Johns Hopkins University
Press, 1992.
St. Louis, Michael E., and Judith N. Wasserheit. “Elimination of
Syphilis in the United States.” Science 281, no. 5375 (July, 1998).

Talking motion pictures
Talking motion pictures
The invention: The first practical system for linking sound with
moving pictures.
The people behind the invention:
Harry Warner (1881-1958), the brother who used sound to
fashion a major filmmaking company
Albert Warner (1884-1967), the brother who persuaded theater
owners to show Warner films
Samuel Warner (1887-1927), the brother who adapted soundrecording
technology to filmmaking
Jack Warner (1892-1978), the brother who supervised the
making of Warner films
Taking the Lead
741
The silent films of the early twentieth century had live sound accompaniment
featuring music and sound effects. Neighborhood
theaters made do with a piano and violin; larger “picture palaces”
in major cities maintained resident orchestras of more than seventy
members. During the late 1920’s, Warner Bros. led the American
film industry in producing motion pictures with their own soundtracks,
which were first recorded on synchronized records and later
added on to the film beside the images.
The ideas that led to the addition of sound to film came from corporate-sponsored
research by American Telephone and Telegraph
Company (AT&T) and the Radio Corporation of America (RCA).
Both companies worked to improve sound recording and playback,
AT&T to help in the design of long-distance telephone equipment
and RCA as part of the creation of better radio sets. Yet neither company
could, or would, enter filmmaking. AT&T was willing to contract
its equipment out to Paramount or one of the other major Hollywood
studios of the day; such studios, however, did not want to
risk their sizable profit positions by junking silent films. The giants
of the film industry were doing fine with what they had and did not
want to switch to something that had not been proved.

742 / Talking motion pictures
In 1924, Warner Bros. was a prosperous, though small, corporation
that produced films with the help of outside financial backing. That
year, Harry Warner approached the important Wall Street investment
banking house of Goldman, Sachs and secured the help he needed.
As part of this initial wave of expansion, Warner Bros. acquired a
Los Angeles radio station in order to publicize its films. Through
this deal, the four Warner brothers learned of the new technology
that the radio and telephone industries had developed to record
sound, and they succeeded in securing the necessary equipment
from AT&T. During the spring of 1925, the brothers devised a plan
by which they could record the most popular musical artists on film
and then offer these “shorts” as added attractions to theaters that
booked its features. As a bonus, Warner Bros. could add recorded
orchestral music to its feature films and offer this music to theaters
that relied on small musical ensembles.
“Vitaphone”
On August 6, 1926, Warner Bros. premiered its new “Vitaphone”
technology. The first package consisted of a traditional silent film
(Don Juan) with a recorded musical accompaniment, plus six recordings
of musical talent highlighted by a performance from Giovanni
Martineli, the most famous opera tenor of the day.
The first Vitaphone feature was The Jazz Singer, which premiered
in October, 1927. The film was silent during much of the movie, but
as soon as Al Jolson, the star, broke into song, the new technology
would be implemented. The film was an immediate hit. The Jazz
Singer package, which included accompanying shorts with sound,
forced theaters in cities that rarely held films over for more than a
single week to ask to have the package stay for two, three, and
sometimes four straight weeks.
The Jazz Singer did well at the box office, but skeptics questioned
the staying power of talkies. If sound was so important, they wondered,
why hadn’t The Jazz Singer moved to the top of the all-time
box-office list? Such success, though, would come a year later with
The Singing Fool, also starring Jolson. From its opening day (September
20, 1928), it was the financial success of its time; produced for an
estimated $200,000, it took in $5 million. In New York City, The

Talking motion pictures / 743
In the early days of sound films, cameras had to be soundproofed so their operating noises
would not be picked up by the primitive sound-recording equipment. (Library of Congress)
Singing Fool registered the heaviest business in Broadway history,
with an advance sale that exceeded more than $100,000 (equivalent
to more than half a million dollars in 1990’s currency).

744 / Talking motion pictures
Impact
The coming of sound transformed filmmaking, ushering in what
became known as the golden age of Hollywood. By 1930, there were
more reporters stationed in the filmmaking capital of the world
than in any capital of Europe or Asia.
The Warner Brothers
Businessmen rather than inventors, the four Warner brothers
were hustlers who knew a good thing when they saw it.
They started out running theaters in 1903, evolved into film distributors,
and began making their own films in 1909, in defiance
of the Patents Company, a trust established by Thomas A. Edison
to eliminate competition from independent filmmakers.
Harry Warner was the president of the company, Sam and Jack
were vice presidents in charge of production, and Abe (or Albert)
was the treasurer.
Theirs was a small concern. Their silent films and serials attracted
few audiences, and during World War I they made
training films for the government. In fact, their film about syphilis,
Open Your Eyes, was their first real success. In 1918, however,
they released My Four Years in Germany, a dramatized
documentary, and it was their first blockbuster. Although considered
gauche upstarts, they were suddenly taken seriously by
the movie industry.
When Sam first heard an actor talk on screen in an experimental
film at the Bell lab in New York in 1925, he recognized a
revolutionary opportunity. He soon convinced Jack that talking
movies would be a gold mine. However, Harry and Abe were
against the idea because of its costs—and because earlier attempts
at “talkies” had been dismal failures. Sam and Jack
tricked Harry into a seeing a experimental film of an orchestra,
however, and he grew enthusiastic despite his misgivings. Within
a year, the brothers released the all-music Don Juan. The rave
notices from critics astounded Harry and Abe.
Still, they thought sound in movies was simply a novelty.
When Sam pointed out that they could make movies in which
the actors talked, as on stage, Harry, who detested actors, snorted,
“Who the hell wants to hear actors talk?” Sam and Jack pressed
for dramatic talkies, nonetheless, and prevailed upon Harry to
finance them. The silver screen has seldom been silent since.

As a result of its foresight, Warner Bros. was the sole small competitor
of the early 1920’s to succeed in the Hollywood elite, producing
successful films for consumption throughout the world.
After Warner Bros.’ innovation, the soundtrack became one of
the features that filmmakers controlled when making a film. Indeed,
sound became a vital part of the filmmaker’s art; music, in
particular, could make or break a film.
Finally, the coming of sound helped make films a dominant medium
of mass culture, both in the United States and throughout the
world. Innumerable fashions, expressions, and designs were soon created
or popularized by filmmakers. Many observers had not viewed
the silent cinema as especially significant; with the coming of the talkies,
however, there was no longer any question about the social and
cultural importance of films. As one clear consequence of the new
power of the movie industry, within a few years of the coming of
sound, the notorious Hays Code mandating prior restraint of film content
went into effect. The pairing of images and sound caused talking
films to be deemed simply too powerful for uncensored presentation
to audiences; although the Hays Code was gradually weakened and
eventually abandoned, less onerous “rating systems” would continue
to be imposed on filmmakers by various regulatory bodies.
See also Autochrome plate; Dolby noise reduction; Electronic
synthesizer; Television.
Further Reading
Talking motion pictures / 745
Brayer, Elizabeth. George Eastman: A Biography. Baltimore: Johns
Hopkins University Press, 1996.
Crafton, Donald. The Talkies: American Cinema’s Transition to Sound,
1926-1931. Berkeley: University of California Press, 1999.
Geduld, Harry M. The Birth of the Talkies: From Edison to Jolson.
Bloomington: Indiana University Press, 1975.
Neale, Stephen. Cinema and Technology: Image, Sound, Colour. London:
Macmillan Education, 1985.
Wagner, A. F. Recollections of Thomas A. Edison: A Personal History of
the Early Days of the Phonograph, the Silent and Sound Film, and Film
Censorship. 2d ed. London: City of London Phonograph & Gramophone
Society, 1996.

746
Teflon
Teflon
The invention: A fluorocarbon polymer whose chemical inertness
and physical properties have made it useful for many applications,
from nonstick cookware coatings to suits for astronauts.
The person behind the invention:
Roy J. Plunkett (1910-1994), an American chemist
Nontoxic Refrigerant Sought
As the use of mechanical refrigeration increased in the late 1930’s,
manufacturers recognized the need for a material to replace sulfur
dioxide and ammonia, which, although they were the commonly
used refrigerants of the time, were less than ideal for the purpose.
The material sought had to be nontoxic, odorless, colorless, and not
flammable. Thomas Midgley, Jr., and Albert Henne of General Motors
Corporation’s Frigidaire Division concluded, from studying
published reports listing properties of a wide variety of chemicals,
that hydrocarbon-like materials with hydrogen atoms replaced by
chlorine and fluorine atoms would be appropriate.
Their conclusion led to the formation of a joint effort between the
General Motors Corporation’s Frigidaire Division and E. I. Du Pont
de Nemours to research and develop the chemistry of fluorocarbons.
In this research effort, a number of scientists began making
and studying the large number of individual chemicals in the general
class of compounds being investigated. It fell to Roy J. Plunkett
to do a detailed study of tetrafluoroethylene, a compound consisting
of two carbon atoms, each of which is attached to the other as
well as to two fluorine atoms.
The “Empty” Tank
Tetrafluoroethylene, at normal room temperature and pressure,
is a gas that is supplied to users in small pressurized cylinders. On
the morning of the day of the discovery, Plunkett attached such a
tank to his experimental apparatus and opened the tank’s valve. To

Teflon / 747
his great surprise, no gas flowed from the tank. Plunkett’s subsequent
actions transformed this event from an experiment gone
wrong into a historically significant discovery. Rather than replacing
the tank with another and going on with the work planned for
the day, Plunkett, who wanted to know what had happened, examined
the “empty” tank. When he weighed the tank, he discovered
that it was not empty; it did contain the chemical that was listed on
the label. Opening the valve and running a wire through the opening
proved that what had happened had not been caused by a malfunctioning
valve. Finally, Plunkett sawed the cylinder in half and
discovered what had happened. The chemical in the tank was no
longer a gas; instead, it was a waxy white powder.
Plunkett immediately recognized the meaning of the presence of
the solid. The six-atom molecules of the tetrafluoroethylene gas had
somehow linked with one another to form much larger molecules.
The gas had polymerized, becoming polytetrafluoroethylene, a solid
with a high molecular weight. Capitalizing on this occurrence,
Plunkett, along with other Du Pont chemists, performed a series of
experiments and soon learned to control the polymerization reaction
so that the product could be produced, its properties could be
studied, and applications for it could be developed.
The properties of the substance were remarkable indeed. It was
unaffected by strong acids and bases, withstood high temperatures
without reacting or melting, and was not dissolved by any solvent
that the scientists tried. In addition to this highly unusual behavior,
the polymer had surface properties that made it very slick. It was so
slippery that other materials placed on its surface slid off in much
the same way that beads of water slide off the surface of a newly
waxed automobile.
Although these properties were remarkable, no applications were
suggested immediately for the new material. The polymer might
have remained a laboratory curiosity if a conversation had not
taken place between Leslie R. Groves, the head of the Manhattan
Project (which engineered the construction of the first atomic bombs),
and a Du Pont chemist who described the polymer to him. The
Manhattan Project research team was hunting for an inert material
to use for gaskets to seal pumps and piping. The gaskets had to be
able to withstand the highly corrosive uranium hexafluoride with

748 / Teflon
which the team was working. This uranium compound is fundamental
to the process of upgrading uranium for use in explosive devices
and power reactors. Polytetrafluoroethylene proved to be just
the material that they needed, and Du Pont proceeded, throughout
World War II and after, to manufacture gaskets for use in uranium
enrichment plants.
The high level of secrecy of the Manhattan Project in particular
and atomic energy in general delayed the commercial introduction
of the polymer, which was called Teflon, until the late 1950’s. At that
time, the first Teflon-coated cooking utensils were introduced.
Impact
Roy J. Plunkett
Roy J. Plunkett was born in 1910 in New Carlisle, Ohio. In
1932 he received a bachelor’s degree in chemistry from Manchester
College and transferred to Ohio State University for
graduate school, earning a master’s degree in 1933 and a doctorate
in 1936. The same year he went to work for E. I. Du Pont
de Nemours and Company as a research chemist at the Jackson
Laboratory in Deepwater, New Jersey. Less then two years later,
when he was only twenty-seven years old, he found the strange
polymer tetrafluoroethylene, whose trade name became Teflon.
It would turn out to be among Du Pont’s most famous products.
In 1938 Du Pont appointed Plunkett the chemical supervisor
at its largest plant, the Chamber Works in Deepwater, which
produced tetraethyl lead. He held the position until 1952 and
afterward directed the company’s Freon Products Division. He
retired in 1975. In 1985 he was inducted into the Inventor’s Hall
of Fame, and after his death in 1994, Du Pont created the
Plunkett Award, presented to inventors who find new uses for
Teflon and Tefzel, a related fluoropolymer, in aerospace, automotive,
chemical, or electrical applications.
Plunkett’s thoroughness in following up a chance observation
gave the world a material that has found a wide variety of uses, ranging
from home kitchens to outer space. Some applications make use

Teflon / 749
of Teflon’s slipperiness, others
make use of its inertness,
and others take advantage
of both properties.
The best-known application
of Teflon is as a nonstick
coating for cookware.
Teflon’s very slippery surface
initially was troublesome,
when it proved to be
difficult to attach to other
materials. Early versions of
Teflon-coated cookware shed
their surface coatings easily,
even when care was taken
to avoid scraping it off. A
suitable bonding process was
soon developed, however,
and the present coated sur-
An important space application for Teflon is its use
faces are very rugged and
on the outer skins of suits worn by astronauts.
(PhotoDisc)
provide a noncontaminating
coating that can be cleaned
easily.
Teflon has proved to be a useful material in making devices that
are implanted in the human body. It is easily formed into various
shapes and is one of the few materials that the human body does not
reject. Teflon has been used to make heart valves, pacemakers, bone
and tendon substitutes, artificial corneas, and dentures.
Teflon’s space applications have included its use as the outer skin
of the suits worn by astronauts, as insulating coating on wires and
cables in spacecraft that must resist high-energy cosmic radiation,
and as heat-resistant nose cones and heat shields on spacecraft.
See also Buna rubber; Neoprene; Nylon; Plastic; Polystyrene;
Pyrex glass; Tupperware.

750 / Teflon
Further Reading
Friedel, Robert. “The Accidental Inventor.” Discover 17, no. 10 (October,
1996).
“Happy Birthday, Teflon.” Design News 44, no. 8 (April, 1988).
“Teflon.” Newsweek 130, 24a (Winter, 1997/1998).

Telephone switching
Telephone switching
The invention: The first completely automatic electronic system
for switching telephone calls.
The people behind the invention:
Almon B. Strowger (1839-1902), an American inventor
Charles Wilson Hoover, Jr. (1925- ), supervisor of memory
system development
Wallace Andrew Depp (1914- ), director of Electronic
Switching
Merton Brown Purvis (1923- ), designer of switching
matrices
Electromechanical Switching Systems
751
The introduction of electronic switching technology into the telephone
network was motivated by the desire to improve the quality
of the telephone system, add new features, and reduce the cost of
switching technology. Telephone switching systems have three features:
signaling, control, and switching functions. There were several
generations of telephone switching equipment before the first
fully electronic switching “office” (device) was designed.
The first automatic electromechanical (partly electronic and partly
mechanical) switching office was the Strowger step-by-step switch.
Strowger switches relied upon the dial pulses generated by rotary
dial telephones to move their switching elements to the proper positions
to connect one telephone with another. In the step-by-step process,
the first digit dialed moved the first mechanical switch into position,
the second digit moved the second mechanical switch into
position, and so forth, until the proper telephone connection was established.
These Strowger switching offices were quite large, and
they lacked flexibility and calling features.
The second generation of automatic electromechanical telephone
switching offices was of the “crossbar” type. Initially, crossbar
switches relied upon a specialized electromechanical controller called
a “marker” to establish call connections. Electromechanical telephone

752 / Telephone switching
switching offices had difficulty implementing additional features
and were unable to handle large numbers of incoming calls.
Electronic Switching Systems
In the early 1940’s, research into the programmed control of
switching offices began at the American Telephone and Telegraph
Company’s Bell Labs. This early research resulted in a trial office being
put into service in Morris, Illinois, in 1960. The Morris switch
used a unique memory called the “flying spot store.” It used a photographic
plate as a program memory, and the memory was accessed
optically. In order to change the memory, one had to scratch
out or cover parts of the photographic plate.
Before the development of the Morris switch, gas tubes had been
used to establish voice connections. This was accomplished by applying
a voltage difference across the end points of the conversation.
When this voltage difference was applied, the gas tubes would
conduct electricity, thus establishing the voice connection. The Morris
trial showed that gas tubes could not support the voltages that
the new technology required to make telephones ring or to operate
pay telephones.
The knowledge gained from the Morris trial led to the development
of the first full-scale, commercial, computer-controlled
electronic switch, the electronic switching system 1 (ESS-1). The
first ESS-1 went into service in New Jersey in 1965. In the ESS-1,
electromechanical switching elements, or relays, were controlled
by computer software. A centralized computer handled call processing.
Because the telephone service of an entire community
depends on the reliability of the telephone switching office, the
ESS-1 had two central processors, so that one would be available
if the other broke down. The switching system of the ESS-1 was
composed of electromechanical relays; the control of the switching
system was electronic, but the switching itself remained mechanical.
Bell Labs developed models to demonstrate the concept of integrating
digital transmission and switching systems. Unfortunately,
the solid state electronics necessary for such an undertaking had not
developed sufficiently at that time, so the commercial development

Almon B. Strowger
Telephone switching / 753
Some people thought Almon B. Strowger was strange, perhaps
even demented. Certainly, he was hot-tempered, restless,
and argumentative. One thing he was not, however, was unimaginative.
Born near Rochester, New York, in 1839, Strowger was old
enough to fight for the Union at the second battle of Manassas
during the American Civil War. The bloody battle apparently
shattered and embittered him. He wandered slowly west after
the war, taught himself undertaking, and opened a funeral
home in Topeka, Kansas, in 1882. There began his running war
with telephone operators, which continued when he moved his
business to Kansas City.
With the help of technicians (whom he later cheated) he built
the first “collar box,” an automatic switching device, in 1887.
The round contraption held a pencil that could be revolved to
different pins arrange around it in order to change phone connections.
Two years later he produced a more sophisticated device
that was operated by push-button, and despite initial misgivings
brought out a rotary dial device in 1896. That same year
he sold the rights to his patents to business partners for $1,800
and his share in Strowger Automatic Dial Telephone Exchange
for $10,000 in 1898. He moved to St. Petersburg, Florida, and
opened a small hotel, dying there in 1902. It surely would have
done his temper no good to learn that fourteen years later the
Bell system bought his patents for $2.5 million.
of digital switching was not pursued. New versions of the ESS continued
to employ electromechanical technology, although mechanical
switching elements can cause impulse noise in voice signals and
are larger and more difficult to maintain than electronic switching
elements. Ten years later, however, Bell Labs began to develop a digital
toll switch, the ESS-4, in which both switching and control functions
were electronic.
Although the ESS-1 was the first electronically controlled switching
system, it did not switch voices electronically. The ESS-1 used
computer control to move mechanical contacts in order to establish
a conversation. In a fully electronic switching system, the voices are

754 / Telephone switching
digitized before switching is performed. This technique, which is
called “digital switching,” is still used.
The advent of electronically controlled switching systems made
possible features such as call forwarding, call waiting, and detailed
billing for long-distance calls. Changing these services became a
matter of simply changing tables in computer programs. Telephone
maintenance personnel could communicate with the central processor
of the ESS-1 by using a teletype, and they could change numbers
simply by typing commands on the teletype. In electromechanically
controlled telephone switching systems, however, changing numbers
required rewiring.
Consequences
Electronic switching has greatly decreased the size of switching
offices. Digitization of the voice prior to transmission improves
voice quality. When telephone switches were electromechanical, a
large area was needed to house the many mechanical switches that
were required. In the era of electronic switching, voices are switched
digitally by computer. In this method, voice samples are read into a
computer memory and then read out of the memory when it is time
to connect a caller with a desired number. Basically, electronic telephone
systems are specialized computer systems that move digitized
voice samples between customers.
Telephone networks are moving toward complete digitization.
Digitization was first applied to the transmission of voice signals.
This made it possible for a single pair of copper wires to be shared
by a number of telephone users. Currently, voices are digitized
upon their arrival at the switching office. If the final destination of
the telephone call is not connected to the particular switching office,
the voice is sent to the remote office by means of digital circuits.
Currently, voice signals are sent between the switching office and
homes or businesses. In the future, digitization of the voice signal
will occur in the telephone sets themselves. Digital voice signals
will be sent directly from one telephone to another. This will provide
homes with direct digital communication. A network that provides
such services is called the “integrated services digital network”
(ISDN).

See also Cell phone; Long-distance telephone; Rotary dial telephone;
Touch-tone telephone.
Further Reading
Telephone switching / 755
Briley, Bruce E. Introduction to Telephone Switching. Reading, Mass.:
Addison-Wesley, 1983.
Talley, David. Basic Electronic Switching for Telephone Systems. 2ded.
Rochelle Park, N.J.: Hayden, 1982.
Thompson, Richard A. Telephone Switching Systems. Boston: Artech
House, 2000.

756
Television
Television
The invention: System that converts moving pictures and sounds
into electronic signals that can be broadcast at great distances.
The people behind the invention:
Vladimir Zworykin (1889-1982), a Soviet electronic engineer and
recipient of the National Medal of Science in 1967
Paul Gottlieb Nipkow (1860-1940), a German engineer and
inventor
Alan A. Campbell Swinton (1863-1930), a Scottish engineer and
Fellow of the Royal Society
Charles F. Jenkins (1867-1934), an American physicist, engineer,
and inventor
The Persistence of Vision
In 1894, an American inventor, Charles F. Jenkins, described a
scheme for electrically transmitting moving pictures. Jenkins’s idea,
however, was only one in an already long tradition of theoretical
television systems. In 1842, for example, the English physicist Alexander
Bain had invented an automatic copying telegraph for sending
still pictures. Bain’s system scanned images line by line. Similarly,
the wide recognition of the persistence of vision—the mind’s
ability to retain a visual image for a short period of time after the image
has been removed—led to experiments with systems in which
the image to be projected was repeatedly scanned line by line. Rapid
scanning of images became the underlying principle of all television
systems, both electromechanical and all-electronic.
In 1884, a German inventor, Paul Gottlieb Nipkow, patented a
complete television system that utilized a mechanical sequential
scanning system and a photoelectric cell sensitized with selenium
for transmission. The selenium photoelectric cell converted the light
values of the image being scanned into electrical impulses to be
transmitted to a receiver where the process would be reversed. The
electrical impulses led to light of varying brightnesses being produced
and projected on to a rotating disk that was scanned to repro-

Electron Gun
Electron Beam
Deflection and Focus Coils
Phosphor Screen
Glass Envelope
Schematic of a television picture tube.
Television / 757
duce the original image. If the system—that is, the transmitter and
the receiver—were in perfect synchronization and if the disk rotated
quickly enough, persistence of vision enabled the viewer to
see a complete image rather than a series of moving points of light.
For a television image to be projected onto a screen of reasonable
size and retain good quality and high resolution, any system employing
only thirty to one hundred lines (as early mechanical systems
did) is inadequate. Afew systems were developed that utilized
two hundred or more lines, but the difficulties these presented
made the possibility of an all-electronic system increasingly attractive.
These difficulties were not generally recognized until the early
1930’s, when television began to move out of the laboratory and into
commercial production.
Interest in all-electronic television paralleled interest in mechanical
systems, but solutions to technical problems proved harder to
achieve. In 1908, a Scottish engineer, Alan A. Campbell Swinton,
proposed what was essentially an all-electronic television system.
Swinton theorized that the use of magnetically deflected cathoderay
tubes for both the transmitter and receiver in a system was possible.
In 1911, Swinton formally presented his idea to the Röntgen

758 / Television
Society in London, but the technology available did not allow for
practical experiments.
Zworykin’s Picture Tube
Vladimir Zworykin
Born in 1889, Vladimir Kosma Zworykin grew up in Murom,
a small town two hundred miles east of Moscow. His father ran
a riverboat service, and Zworykin sometimes helped him, but
his mind was on electricity, which he studied on his own while
aboard his father’s boats. In 1906, he entered the St. Petersburg
Institute of Technology, and there he became acquainted with
the idea of television through the work of Professor Boris von
Rosing.
Zworykin assisted Rosing in his attempts to transmit pictures
with a cathode-ray tube. He served with the Russian Signal
Corps during World War I, but then fled to the United States
after the Bolshevist Revolution. In 1920 he got a job at Westinghouse’s
research laboratory in Pittsburgh, helping develop radio
tubes and photoelectric cells. He became an American citizen
in 1924 and completed a doctorate at the University of
Pittsburgh in 1926. By then he had already demonstrated his
iconoscope and applied for a patent. Unable to interest Westinghouse
in his invention, he moved to the Radio Corporation
of America (RCA) in 1929, and later became director of its electronics
research laboratory. RCA’s president, David Sarnoff,
also a Russian immigrant, had faith in Zworykin and his ideas.
Before Zworykin retired in 1954, RCA had invested $50 million
in television.
Among the many awards Zworykin received for his culturechanging
invention was the National Medal of Science, presented
by President Lyndon Johnson in 1966. Zworykin died on
his birthday in 1982.
In 1923, Vladimir Zworykin, a Soviet electronic engineer working
for the Westinghouse Electric Corporation, filed a patent application
for the “iconoscope,” or television transmission tube. On
March 17, 1924, Zworykin applied for a patent for a two-way system.
The first cathode-ray tube receiver had a cathode, a modulating
grid, an anode, and a fluorescent screen.

Early console model television. (PhotoDisc)
Television / 759
Zworykin later admitted that the results were very poor and the
system, as shown, was still far removed from a practical television
system. Zworykin’s employers were so unimpressed that they admonished
him to forget television and work on something more
useful. Zworykin’s interest in television was thereafter confined to
his nonworking hours, as he spent the next year working on photographic
sound recording.
It was not until the late 1920’s that he was able to devote his full
attention to television. Ironically, Westinghouse had by then resumed
research in television, but Zworykin was not part of the
team. After he returned from a trip to France, where in 1928 he had
witnessed an exciting demonstration of an electrostatic tube, Westinghouse
indicated that it was not interested. This lack of corporate
support in Pittsburgh led Zworykin to approach the Radio Corporation
of America (RCA). According to reports, Zworykin demonstrated
his system to the Institute of Radio Engineers at Rochester,
New York, on November 18, 1929, claiming to have developed a

760 / Television
working picture tube, a tube that would revolutionize television development.
Finally, RCA recognized the potential.
Impact
The picture tube, or “kinescope,” developed by Zworykin changed
the history of television. Within a few years, mechanical systems
disappeared and television technology began to utilize systems
similar to Zworykin’s by use of cathode-ray tubes at both ends of
the system. At the transmitter, the image is focused upon a mosaic
screen composed of light-sensitive cells. A stream of electrons sweeps
the image, and each cell sends off an electric current pulse as it is hit
by the electrons, the light and shade of the focused image regulating
the amount of current.
This string of electrical impulses, after amplification and modification
into ultrahigh frequency wavelengths, is broadcast by antenna
to be picked up by any attuned receiver, where it is retransformed
into a moving picture in the cathode-ray tube receiver. The
cathode-ray tubes contain no moving parts, as the electron stream is
guided entirely by electric attraction.
Although both the iconoscope and the kinescope were far from
perfect when Zworykin initially demonstrated them, they set the
stage for all future television development.
See also Color television; Community antenna television; Communications
satellite; Fiber-optics; FM radio; Holography; Internet;
Radio; Talking motion pictures.
Further Reading
Abramson, Albert. Zworykin: Pioneer of Television. Urbana: University
of Illinois Press, 1995.
Sconce, Jeffrey. Haunted Media: Electronic Presence from Telegraphy to
Television. Durham, N.C.: Duke University Press, 2000.
Zworykin, Vladimir Kosma, and George Ashmun Morton. Television:
The Electronics of Image Transmission in Color and Monochrome.
2d ed. New York: J. Wiley, 1954.

Tevatron accelerator
Tevatron accelerator
The invention: A particle accelerator that generated collisions between
beams of protons and antiprotons at the highest energies
ever recorded.
The people behind the invention:
Robert Rathbun Wilson (1914- ), an American physicist and
director of Fermilab from 1967 to 1978
John Peoples (1933- ), an American physicist and deputy
director of Fermilab from 1987
Putting Supermagnets to Use
761
The Tevatron is a particle accelerator, a large electromagnetic device
used by high-energy physicists to generate subatomic particles
at sufficiently high energies to explore the basic structure of matter.
The Tevatron is a circular, tubelike track 6.4 kilometers in circumference
that employs a series of superconducting magnets to accelerate
beams of protons, which carry a positive charge in the atom, and
antiprotons, the proton’s negatively charged equivalent, at energies
up to 1 trillion electronvolts (equal to 1 teraelectronvolt, or 1 TeV;
hence the name Tevatron). An electronvolt is the unit of energy that
an electron gains through an electrical potential of 1 volt.
The Tevatron is located at the Fermi National Accelerator Laboratory,
which is also known as Fermilab. The laboratory was one of
several built in the United States during the 1960’s.
The heart of the original Fermilab was the 6.4-kilometer main accelerator
ring. This main ring was capable of accelerating protons to
energies approaching 500 billion electronvolts, or 0.5 teraelectronvolt.
The idea to build the Tevatron grew out of a concern for the
millions of dollars spent annually on electricity to power the main
ring, the need for higher energies to explore the inner depths of the
atom and the consequences of new theories of both matter and energy,
and the growth of superconductor technology. Planning for a
second accelerator ring, the Tevatron, to be installed beneath the
main ring began in 1972.

762 / Tevatron accelerator
Robert Rathbun Wilson, the director of Fermilab at that time, realized
that the only way the laboratory could achieve the higher energies
needed for future experiments without incurring intolerable
electricity costs was to design a second accelerator ring that employed
magnets made of superconducting material. Extremely powerful
magnets are the heart of any particle accelerator; charged particles
such as protons are given a “push” as they pass through an electromagnetic
field. Each successive push along the path of the circular
accelerator track gives the particle more and more energy. The enormous
magnetic fields required to accelerate massive particles such
as protons to energies approaching 1 trillion electronvolts would require
electricity expenditures far beyond Fermilab’s operating budget.
Wilson estimated that using superconducting materials, however,
which have virtually no resistance to electrical current, would
make it possible for the Tevatron to achieve double the main ring’s
magnetic field strength, doubling energy output without significantly
increasing energy costs.
Tevatron to the Rescue
The Tevatron was conceived in three phases. Most important,
however, were Tevatron I and Tevatron II, where the highest energies
were to be generated and where it was hoped new experimental findings
would emerge. Tevatron II experiments were designed to be
very similar to other proton beam experiments, except that in this
case, the protons would be accelerated to an energy of 1 trillion
electronvolts. More important still are the proton-antiproton colliding
beam experiments of Tevatron I. In this phase, beams of protons
and antiprotons rotating in opposite directions are caused to collide
in the Tevatron, producing a combined, or center-of-mass, energy
approaching 2 trillion electronvolts, nearly three times the energy
achievable at the largest accelerator at Centre Européen de Recherche
Nucléaire (the European Center for Nuclear Research, or CERN).
John Peoples was faced with the problem of generating a beam of
antiprotons of sufficient intensity to collide efficiently with a beam
of protons. Knowing that he had the use of a large proton accelerator—the
old main ring—Peoples employed the two-ring mode in
which 120 billion electronvolt protons from the main ring are aimed

at a fixed tungsten target, generating antiprotons, which scatter
from the target. These particles were extracted and accumulated in a
smaller storage ring. These particles could be accelerated to relatively
low energies. After sufficient numbers of antiprotons were
collected, they were injected into the Tevatron, along with a beam of
protons for the colliding beam experiments. On October 13, 1985,
Fermilab scientists reported a proton-antiproton collision with a
center-of-mass energy measured at 1.6 trillion electronvolts, the
highest energy ever recorded.
Consequences
Tevatron accelerator / 763
The Tevatron’s success at generating high-energy protonantiproton
collisions affected future plans for accelerator development
in the United States and offered the potential for important
discoveries in high-energy physics at energy levels that no other accelerator
could achieve.
Physics recognized four forces in nature: the electromagnetic
force, the gravitational force, the strong nuclear force, and the weak
nuclear force. A major goal of the physics community is to formulate
a theory that will explain all these forces: the so-called grand
unification theory. In 1967, one of the first of the so-called gauge theories
was developed that unified the weak nuclear force and the
electromagnetic force. One consequence of this theory was that the
weak force was carried by massive particles known as “bosons.”
The search for three of these particles—the intermediate vector bosons
W + ,W − , and Z 0 —led to the rush to conduct colliding beam experiments
to the early 1970’s. Because the Tevatron was in the planning
phase at this time, these particles were discovered by a team of
international scientists based in Europe. In 1989, Tevatron physicists
reported the most accurate measure to date of the Z 0 mass.
The Tevatron is thought to be the only particle accelerator in the
world with sufficient power to conduct further searches for the elusive
Higgs boson, a particle attributed to weak interactions by University
of Edinburgh physicist Peter Higgs in order to account for
the large masses of the intermediate vector bosons. In addition, the
Tevatron has the ability to search for the so-called top quark. Quarks
are believed to be the constituent particles of protons and neutrons.

764 / Tevatron accelerator
Evidence has been gathered of five of the six quarks believed to exist.
Physicists have yet to detect evidence of the most massive quark,
the top quark.
See also Atomic bomb; Cyclotron; Electron microscope; Field ion
microscope; Geiger counter; Hydrogen bomb; Mass spectrograph;
Neutrino detector; Scanning tunneling microscope; Synchrocyclotron.
Further Reading
Hilts, Philip J. Scientific Temperaments: Three Lives in Contemporary
Science. New York: Simon and Schuster, 1984.
Ladbury, Ray. “Fermilab Tevatron Collider Group Goes over the
Top—Cautiously.” Physics Today 47, no. 6 (June, 1994).
Lederman, Leon M. “The Tevatron.” Scientific American 264, no. 3
(March, 1991).
Wilson, Robert R., and Raphael Littauer. Accelerators: Machines of
Nuclear Physics. London: Heinemann, 1962.

Thermal cracking process
Thermal cracking process
The invention: Process that increased the yield of refined gasoline
extracted from raw petroleum by using heat to convert complex
hydrocarbons into simpler gasoline hydrocarbons, thereby making
possible the development of the modern petroleum industry.
The people behind the invention:
William M. Burton (1865-1954), an American chemist
Robert E. Humphreys (1942- ), an American chemist
Gasoline, Motor Vehicles, and Thermal Cracking
765
Gasoline is a liquid mixture of hydrocarbons (chemicals made up
of only hydrogen and carbon) that is used primarily as a fuel for internal
combustion engines. It is produced by petroleum refineries
that obtain it by processing petroleum (crude oil), a naturally occurring
mixture of thousands of hydrocarbons, the molecules of which
can contain from one to sixty carbon atoms.
Gasoline production begins with the “fractional distillation” of
crude oil in a fractionation tower, where it is heated to about 400 degrees
Celsius at the tower’s base. This heating vaporizes most of the
hydrocarbons that are present, and the vapor rises in the tower,
cooling as it does so. At various levels of the tower, various portions
(fractions) of the vapor containing simple hydrocarbon mixtures become
liquid again, are collected, and are piped out as “petroleum
fractions.” Gasoline, the petroleum fraction that boils between 30
and 190 degrees Celsius, is mostly a mixture of hydrocarbons that
contain five to twelve carbon atoms.
Only about 25 percent of petroleum will become gasoline via
fractional distillation. This amount of “straight run” gasoline is not
sufficient to meet the world’s needs. Therefore, numerous methods
have been developed to produce the needed amounts of gasoline.
The first such method, “thermal cracking,” was developed in 1913
by William M. Burton of Standard Oil of Indiana. Burton’s cracking
process used heat to convert complex hydrocarbons (whose molecules
contain many carbon atoms) into simpler gasoline hydrocar-

766 / Thermal cracking process
bons (whose molecules contain fewer carbon atoms), thereby increasing
the yield of gasoline from petroleum. Later advances in
petroleum technology, including both an improved Burton method
and other methods, increased the gasoline yield still further.
More Gasoline!
Starting in about 1900, gasoline became important as a fuel for
the internal combustion engines of the new vehicles called automobiles.
By 1910, half a million automobiles traveled American roads.
Soon, the great demand for gasoline—which was destined to grow
and grow—required both the discovery of new crude oil fields
around the world and improved methods for refining the petroleum
mined from these new sources. Efforts were made to increase
the yield of gasoline—at that time, about 15 percent—from petroleum.
The Burton method was the first such method.
At the time that the cracking process was developed, Burton was
the general superintendent of the Whiting refinery, owned by Standard
Oil of Indiana. The Burton process was developed in collaboration
with Robert E. Humphreys and F. M. Rogers. This three-person
research group began work knowing that heating petroleum
fractions that contained hydrocarbons more complex than those
present in gasoline—a process called “coking”—produced kerosene,
coke (a form of carbon), and a small amount of gasoline. The
process needed to be improved substantially, however, before it
could be used commercially.
Initially, Burton and his coworkers used the “heavy fuel” fraction
of petroleum (the 66 percent of petroleum that boils at a temperature
higher than the boiling temperature of kerosene). Soon, they
found that it was better to use only the part of the material that contained
its smaller hydrocarbons (those containing fewer carbon atoms),
all of which were still much larger than those present in gasoline.
The cracking procedure attempted first involved passing the
starting material through a hot tube. This hot-tube treatment vaporized
the material and broke down 20 to 30 percent of the larger hydrocarbons
into the hydrocarbons found in gasoline. Various tarry
products were also produced, however, that reduced the quality of
the gasoline that was obtained in this way.

Asphalt Industrial
Fuel Oil
Roofing
Paints
CRUDE OIL IN
PETROLEUM REFINERY
Thermal cracking process / 767
SEPARATING PURIFICATION CONVERSION
Candles
Polish
Waxed Paper
Ointments
and
Creams
De-waxing
Lubricants
and
Greases
Plastics
Photographic
Film
Synthetic
Rubber
Weed-killers
and
Fertilizers
Diesel
Oils
Cracking
Medicines
Detergents
Enamel
Synthetic
Fibers
Next, the investigators attempted to work at a higher temperature
by bubbling the starting material through molten lead. More
gasoline was made in this way, but it was so contaminated with
gummy material that it could not be used. Continued investigation
showed, however, that moderate temperatures (between those used
in the hot-tube experiments and that of molten lead) produced the
best yield of useful gasoline.
The Burton group then had the idea of using high pressure to
“keep starting materials still.” Although the theoretical basis for the
use of high pressure was later shown to be incorrect, the new
method worked quite well. In 1913, the Burton method was patented
and put into use. The first cracked gasoline, called Motor
Spirit, was not very popular, because it was yellowish and had a
somewhat unpleasant odor. The addition of some minor refining
procedures, however, soon made cracked gasoline indistinguishable
from straight run gasoline. Standard Oil of Indiana made huge
profits from cracked gasoline over the next ten years. Ultimately,
thermal cracking subjected the petroleum fractions that were uti-
Fuel
Oil
Bottled
Gas
Gasoline
Jet Fuel
Solvents
Insecticides
Burton’s process contributed to the development of petroleum refining, shown in this
diagram.

768 / Thermal cracking process
lized to temperatures between 550 and 750 degrees Celsius, under
pressures between 250 and 750 pounds per square inch.
Impact
In addition to using thermal cracking to make gasoline for sale,
Standard Oil of Indiana also profited by licensing the process for use
by other gasoline producers. Soon, the method was used throughout
the oil industry. By 1920, it had been perfected as much as it
could be, and the gasoline yield from petroleum had been significantly
increased. The disadvantages of thermal cracking include a
relatively low yield of gasoline (compared to those of other methods),
the waste of hydrocarbons in fractions converted to tar and
coke, and the relatively high cost of the process.
A partial solution to these problems was found in “catalytic
cracking”—the next logical step from the Burton method—in which
petroleum fractions to be cracked are mixed with a catalyst (a substance
that causes a chemical reaction to proceed more quickly,
without reacting itself). The most common catalysts used in such
cracking were minerals called “zeolites.” The wide use of catalytic
cracking soon enabled gasoline producers to work at lower temperatures
(450 to 550 degrees Celsius) and pressures (10 to 50 pounds
per square inch). This use decreased manufacturing costs because
catalytic cracking required relatively little energy, produced only
small quantities of undesirable side products, and produced highquality
gasoline.
Various other methods of producing gasoline have been developed—among
them catalytic reforming, hydrocracking, alkylation,
and catalytic isomerization—and now about 60 percent of the petroleum
starting material can be turned into gasoline. These methods,
and others still to come, are expected to ensure that the world’s
needs for gasoline will continue to be satisfied—as long as petroleum
remains available.
See also Fuel cell; Gas-electric car; Geothermal power; Internal
combustion engine; Oil-well drill bit; Solar thermal engine.

Further Reading
Thermal cracking process / 769
Gorman, Hugh S. Redefining Efficiency: Pollution Concerns, Regulatory
Mechanisms, and Technological Change in the U.S. Petroleum Industry.
Akron, Ohio: University of Akron Press, 2001.
Sung, Hsun-chang, Robert Roy White, and George Granger Brown.
Thermal Cracking of Petroleum. Ann Arbor: University of Michigan,
1945.
William Meriam Burton: A Pioneer in Modern Petroleum Technology.
Cambridge, Mass.: University Press, 1952.

770
Tidal power plant
Tidal power plant
The invention: Plant that converts the natural ocean tidal forces
into electrical power.
The people behind the invention:
Mariano di Jacopo detto Taccola (Mariano of Siena, 1381-1453),
an Italian notary, artist, and engineer
Bernard Forest de Bélidor (1697 or 1698-1761), a French engineer
Franklin D. Roosevelt (1882-1945), president of the United States
Tidal Enersgy
Ocean tides have long been harnessed to perform useful work.
Ancient Greeks, Romans, and medieval Europeans all left records
and ruins of tidal mills, and Mariano di Jacopo included tidal power
in his treatise De Ingeneis (1433; on engines). Some mills consisted of
water wheels suspended in tidal currents, others lifted weights that
powered machinery as they fell, and still others trapped the high
tide to run a mill.
Bernard Forest de Bélidor’s Architecture hydraulique (1737; hydraulic
architecture) is often cited as initiating the modern era of
tidal power exploitation. Bélidor was an instructor in the French
École d’Artillerie et du Génie (School of Artillery and Engineering).
Industrial expansion between 1700 and 1800 led to the construction
of many tidal mills. In these mills, waterwheels or simple turbines
rotated shafts that drove machinery by means of gears or
belts. They powered small enterprises located on the seashore.
Steam engines, however, soon began to replace tidal mills. Steam
could be generated wherever it was needed, and steam mills were
not dependent upon the tides or limited in their production capacity
by the amount of tidal flow. Thus, tidal mills gradually were abandoned,
although a few still operate in New England, Great Britain,
France, and elsewhere.

Electric Power from Tides
Tidal power plant / 771
Modern society requires tremendous amounts of electric energy
generated by large power stations. This need was first met by
using coal and by damming rivers. Later, oil and nuclear power became
important. Although small mechanical tidal mills are inadequate
for modern needs, tidal power itself remains an attractive
source of energy. Periodic alarms about coal or oil supplies and
concern about the negative effects on the environment of using
coal, oil, or nuclear energy continue to stimulate efforts to develop
renewable energy sources with fewer negative effects. Every crisis—for
example, the perceived European coal shortages in the
early 1900’s, oil shortages in the 1920’s and 1970’s, and growing
anxiety about nuclear power—revives interest in tidal power.
In 1912, a tidal power plant was proposed at Busum, Germany.
The English, in 1918 and more recently, promoted elaborate schemes
for the Severn Estuary. In 1928, the French planned a plant at Aber-
Wrach in Brittany. In 1935, under the leadership of Franklin Delano
Roosevelt, the United States began construction of a tidal power
plant at Passamaquoddy, Maine. These plants, however, were never
built. All of them had to be located at sites where tides were extremely
high, and such sites are often far from power users. So
much electricity was lost in transmission that profitable quantities
of power could not be sent where they were needed. Also, large
tidal power stations were too expensive to compete with existing
steam plants and river dams. In addition, turbines and generators
capable of using the large volumes of slow-moving tidal water that
reversed flow had not been invented. Finally, large tidal plants inevitably
hampered navigation, fisheries, recreation, and other uses
of the sea and shore.
French engineers, especially Robert Gibrat, the father of the La
Rance project, have made the most progress in solving the problems
of tidal power plants. France, a highly industrialized country, is
short of coal and petroleum, which has brought about an intense
search by the French for alternative energy supplies.
La Rance, which was completed in December, 1967, is the first
full-scale tidal electric power plant in the world. The Chinese, however,
have built more than a hundred small tidal electric stations

772 / Tidal power plant
about the size of the old mechanical tidal mills, and the Canadians
and the Russians have both operated plants of pilot-plant size.
La Rance, which was selected from more than twenty competing
localities in France, is one of a few places in the world where the
tides are extremely high. It also has a large reservoir that is located
above a narrow constriction in the estuary. Finally, interference with
navigation, fisheries, and recreational activities is minimal at La
Rance.
Submersible “bulbs” containing generators and mounting propeller
turbines were specially designed for the La Rance project.
These turbines operate using both incoming and outgoing tides,
and they can pump water either into or out of the reservoir. These
features allow daily and seasonal changes in power generation to be
“smoothed out.” These turbines also deliver electricity most economically.
Many engineering problems had to be solved, however,
before the dam could be built in the tidal estuary.
The La Rance plant produces 240 megawatts of electricity. Its
twenty-four highly reliable turbine generator sets operate about 95
percent of the time. Output is coordinated with twenty-four other
hydroelectric plants by means of a computer program. In this system,
pump-storage stations use excess La Rance power during periods
of low demand to pump water into elevated reservoirs. Later,
during peak demand, this water is fed through a power plant, thus
“saving” the excess generated at La Rance when it was not immediately
needed. In this way, tidal energy, which must be used or lost as
the tides continue to flow, can be saved.
Consequences
The operation of La Rance proved the practicality of tide-generated
electricity. The equipment, engineering practices, and operating
procedures invented for La Rance have been widely applied. Submersible,
low-head, high-flow reversible generators of the La Rance
type are now used in Austria, Switzerland, Sweden, Russia, Canada,
the United States, and elsewhere.
Economic problems have prevented the building of more large
tidal power plants. With technological advances, the inexorable
depletion of oil and coal resources, and the increasing cost of nu-

clear power, tidal power may be used more widely in the future.
Construction costs may be significantly lowered by using preconstructed
power units and dam segments that are floated into place
and submerged, thus making unnecessary expensive dams and reducing
pumping costs.
See also Compressed-air-accumulating power plant; Geothermal
power; Nuclear power plant; Nuclear reactor; Solar thermal engine;
Thermal cracking process.
Further Reading
Tidal power plant / 773
Bernshtein, L. B. Tidal Power Plants. Seoul, Korea: Korea Ocean Research
and Development Institute, 1996.
Boyle, Godfrey. Renewable Energy: Power for a Sustainable Future. Oxford:
Oxford University Press, 1998.
Ross, David. Power from the Waves. New York: Oxford University
Press, 1995.
Seymour, Richard J. Ocean Energy Recovery: The State of the Art. New
York: American Society of Civil Engineers, 1992.

774
Touch-tone telephone
Touch-tone telephone
The invention: A push-button dialing system for telephones that
replaced the earlier rotary-dial phone.
The person behind the invention:
Bell Labs, the research and development arm of the American
Telephone and Telegraph Company
Dialing Systems
A person who wishes to make a telephone call must inform the
telephone switching office which number he or she wishes to reach.
A telephone call begins with the customer picking up the receiver
and listening for a dial tone. The action of picking up the telephone
causes a switch in the telephone to close, allowing electric current to
flow between the telephone and the switching office. This signals
the telephone office that the user is preparing to dial a number. To
acknowledge its readiness to receive the digits of the desired number,
the telephone office sends a dial tone to the user. Two methods
have been used to send telephone numbers to the telephone office:
dial pulsing and touch-tone dialing.
“Dial pulsing” is the method used by telephones that have rotary
dials. In this method, the dial is turned until it stops, after which it is
released and allowed to return to its resting position. When the dial
is returning to its resting position, the telephone breaks the current
between the telephone and the switching office. The switching office
counts the number of times that current flow is interrupted,
which indicates the number that had been dialed.
Introduction of Touch-tone Dialing
The dial-pulsing technique was particularly appropriate for use
in the first electromechanical telephone switching offices, because
the dial pulses actually moved mechanical switches in the switching
office to set up the telephone connection. The introduction of
touch-tone dialing into electromechanical systems was made possi-

Touch-tone telephone / 775
ble by a special device that converted the touch-tones into rotary
dial pulses that controlled the switches. At the American Telephone
and Telegraph Company’s Bell Labs, experimental studies were
pursued that explored the use of “multifrequency key pulsing” (in
other words, using keys that emitted tones of various frequencies)
by both operators and customers. Initially, plucked tuned reeds
were proposed. These were, however, replaced with “electronic
transistor oscillators,” which produced the required signals electronically.
The introduction of “crossbar switching” made dial pulse signaling
of the desired number obsolete. The dial pulses of the telephone
were no longer needed to control the mechanical switching process
at the switching office. When electronic control was introduced into
switching offices, telephone numbers could be assigned by computer
rather than set up mechanically. This meant that a single
touch-tone receiver at the switching office could be shared by a
large number of telephone customers.
Before 1963, telephone switching offices relied upon rotary dial
pulses to move electromechanical switching elements. Touch-tone
dialing was difficult to use in systems that were not computer controlled,
such as the electromechanical step-by-step method. In about
1963, however, it became economically feasible to implement centralized
computer control and touch-tone dialing in switching offices.
Computerized switching offices use a central touch-tone receiver
to detect dialed numbers, after which the receiver sends the
number to a call processor so that a voice connection can be established.
Touch-tone dialing transmits two tones simultaneously to represent
a digit. The tones that are transmitted are divided into two
groups: a high-band group and a low-band group. For each digit
that is dialed, one tone from the low-frequency (low-band) group
and one tone from the high-frequency (high-band) group are transmitted.
The two frequencies of a tone are selected so that they are
not too closely related harmonically. In addition, touch-tone receivers
must be designed so that false digits cannot be generated when
people are speaking into the telephone.
For a call to be completed, the first digit dialed must be detected
in the presence of a dial tone, and the receiver must not interpret

776 / Touch-tone telephone
background noise or speech as valid digits. In order to avoid such
misinterpretation, the touch-tone receiver uses both the relative and
the absolute strength of the two simultaneous tones of the first digit
dialed to determine what that digit is.
A system similar to the touch-tone system is used to send telephone
numbers between telephone switching offices. This system,
which is called “multifrequency signaling,” also uses two tones to
indicate a single digit, but the frequencies used are not the same frequencies
that are used in the touch-tone system. Multifrequency
signaling is currently being phased out; new computer-based systems
are being introduced to replace it.
Impact
Touch-tone dialing has made new caller features available. The
touch-tone system can be used not only to signal the desired number
to the switching office but also to interact with voice-response
systems. This means that touch-tone dialing can be used in conjunction
with such devices as bank teller machines. A customer can also
dial many more digits per second with a touch-tone telephone than
with a rotary dial telephone.
Touch-tone dialing has not been implemented in Europe, and
one reason may be that the economics of touch-tone dialing change
as a function of technology. In the most modern electronic switching
offices, rotary signaling can be performed at no additional cost,
whereas the addition of touch-tone dialing requires a centralized
touch-tone receiver at the switching office. Touch-tone signaling
was developed in an era of analog telephone switching offices, and
since that time, switching offices have become overwhelmingly digital.
When the switching network becomes entirely digital, as will
be the case when the integrated services digital network (ISDN) is
implemented, touch-tone dialing will become unnecessary. In the
future, ISDN telephone lines will use digital signaling methods exclusively.
See also Cell phone; Rotary dial telephone; Telephone switching.

Further Reading
Touch-tone telephone / 777
Coe, Lewis. The Telephone and Its Several Inventors: A History. Jefferson,
N.C.: McFarland, 1995.
Young, Peter. Person to Person: The International Impact of the Telephone.
Cambridge: Granta Editions, 1991.

778
Transistor
Transistor
The invention: A miniature electronic device, comprising a tiny
semiconductor and multiple electrical contacts, used in circuits
as an amplifier, detector, or switch, that revolutionized electronics
in the mid-twentieth century.
The people behind the invention:
William B. Shockley (1910-1989), an American physicist who led
the Bell Laboratories team that produced the first transistors
Akio Morita (1921-1999), a Japanese physicist and engineer who
was the cofounder of the Sony electronics company
Masaru Ibuka (1908-1997), a Japanese electrical engineer and
businessman who cofounded Sony with Morita
The Birth of Sony
In 1952, a Japanese engineer visiting the United States learned
that the Western Electric company was granting licenses to use its
transistor technology. He was aware of the development of this device
and thought that it might have some commercial applications.
Masaru Ibuka told his business partner in Japan about the opportunity,
and they decided to raise the $25,000 required to obtain a license.
The following year, his partner, Akio Morita, traveled to New
York City and concluded negotiations with Western Electric. This
was a turning point in the history of the Sony company and in the
electronics industry, for transistor technology was to open profitable
new fields in home entertainment.
The origins of the Sony corporation were in the ruins of postwar
Japan. The Tokyo Telecommunications Company was incorporated
in 1946 and manufactured a wide range of electrical equipment
based on the existing vacuum tube technology. Morita and Ibuka
were involved in research and development of this technology during
the war and intended to put it to use in the peacetime economy.
In the United States and Europe, electrical engineers who had done
the same sort of research founded companies to build advanced
audio products such as high-performance amplifiers, but Morita

and Ibuka did not have the resources to make such sophisticated
products and concentrated on simple items such as electric water
heaters and small electric motors for record players.
In addition to their experience as electrical engineers, both men
were avid music lovers, as a result of their exposure to Americanbuilt
phonographs and gramophones exported to Japan in the early
twentieth century. They decided to combine their twin interests by
devising innovative audio products and looked to the new field of
magnetic recording as a likely area for exploitation. They had learned
about tape recorders from technical journals and had seen them in
use by the American occupation force.
They developed a reel-to-reel tape recorder and introduced it in
1950. It was a large machine with vacuum tube amplifiers, so heavy
that they transported it by truck. Although it worked well, they had
a hard job selling it. Ibuka went to the United States in 1952 partly
on a fact-finding mission and partly to get some ideas about marketing
the tape recorder to schools and businesses. It was not seen as a
consumer product.
Ibuka and Morita had read about the invention of the transistor
in Western Electric’s laboratories shortly after the war. John Bardeen
and Walter H. Brattain had discovered that a semiconducting material
could be used to amplify or control electric current. Their point
contact transistor of 1948 was a crude laboratory apparatus that
served as the basis for further research. The project was taken over
by William B. Shockley, who had suggested the theory of the transistor
effect. A new generation of transistors was devised; they were
simpler and more efficient than the original. The junction transistors
were the first to go into production.
Ongoing Research
Transistor / 779
Bell Laboratories had begun transistor research because Western
Electric, one of its parent companies along with American Telephone
and Telegraph, was interested in electronic amplification.
This was seen as a means to increase the strength of telephone signals
traveling over long distances, a job carried out by vacuum
tubes. The junction transistor was developed as an amplifier. Western
Electric thought that the hearing aid was the only consumer

780 / Transistor
product that could be based on it and saw the transistor solely as a
telecommunications technology. The Japanese purchased the license
with only the slightest understanding of the workings of
semiconductors and despite the belief that transistors could not be
used at the high frequencies associated with radio.
The first task of Ibuka and Morita was to develop a highfrequency
transistor. Once this was accomplished, in 1954, a method
had to be found to manufacture it cheaply. Transistors were made
from crystals, which had to be grown and doped with impurities to
form different layers of conductivity. This was not an exact science,
and Sony engineers found that the failure rate for high-frequency
transistors was very high. This increased costs and put the entire
project into doubt, because the adoption of transistors was based on
simplicity, reliability, and low cost.
The introduction of the first Sony transistor radio, the TR-55, in
1955 was the result of basic research combined with extensive industrial
engineering. Morita admitted that its sound was poor, but
because it was the only transistor radio in Japan, it sold well. These
were not cheap products, nor were they particularly compact. The
selling point was that they consumed much less battery power than
the old portable radios.
The TR-55 carried the brand name Sony, a relative of the Soni
magnetic tape made by the company and a name influenced by the
founders’ interest in sound. Morita and Ibuka had already decided
that the future of their company would be in international trade and
wanted its name to be recognized all over the world. In 1957, they
changed the company’s name from Tokyo Telecomunications Engineering
to Sony.
The first product intended for the export market was a small
transistor radio. Ibuka was disappointed at the large size of the TR-
55 because one of the advantages of the transistor over the vacuum
tube was supposed to be smaller size. He saw a miniature radio as a
promising consumer product and gave his engineers the task of designing
one small enough to fit into his shirt pocket.
All elements of the radio had to be reduced in size: amplifier,
transformer, capacitor, and loudspeaker. Like many other Japanese
manufacturers, Sony bought many of the component parts of its
products from small manufacturers, all of which had to be cajoled

into decreasing the size of their parts. Morita and Ibuka stated that
the hardest task in developing this new product was negotiating
with the subcontractors. Finally, the Type 63 pocket transistor radio—the
“Transistor Six”—was introduced in 1957.
Impact
Transistor / 781
When the transistor radio was introduced, the market for radios
was considered to be saturated. People had rushed to buy them
when they were introduced in the 1920’s, and by the time of the
Great Depression, the majority of American households had one.
Improvements had been made to the receiver and more attractive
radio/phonograph console sets had been introduced, but these developments
did not add many new customers. The most manufacturers
could hope for was the replacement market with a few sales
as children moved out of their parents’ homes and established new
households.
The pocket radio created a new market. It could be taken anywhere
and used at any time. Its portability was its major asset, and it
became an indispensable part of youth-oriented popular culture of
the 1950’s and 1960’s. It provided an outlet for the crowded airwaves
of commercial AM radio and was the means to bring the new
music of rock and roll to a mass audience.
As soon as Sony introduced the Transistor Six, it began to redesign
it to reduce manufacturing cost. Subsequent transistor radios
were smaller and cheaper. Sony sold them by the millions, and millions
more were made by other companies under brand names such
as “Somy” and “Sonny.” By 1960, more than twelve million transistor
radios had been sold.
The transistor radio was the product that established Sony as an
international audio concern. Morita had resisted the temptation to
make radios for other companies to sell under their names. Exports
of Sony radios increased name recognition and established a bridgehead
in the United States, the biggest market for electronic consumer
products. Morita planned to follow the radio with other transistorized
products.
The television had challenged radio’s position as the mechanical
entertainer in the home. Like the radio, it stood in nearly every

782 / Transistor
William Shockley
William Shockley’s reputation contains extremes. He helped
invent one of the basic devices supporting modern technological
society, the transistor. He also tried to revive one of the most
infamous social theories, eugenics.
His parents, mining engineer William Hillman Shockley,
and surveyor May Bradford Shockley, were on assignment in
England in 1910 when he was born. The family returned to
Northern California when the younger William was three, and
they schooled him at home until he was eight. He acquired an
early interest in physics from a neighbor who taught at Stanford
University. Shockley pursed that interest at the California Institute
of Technology and the Massachusetts Institute of Technology,
which awarded him a doctorate in 1936.
Shockley went to work for Bell Telephone Laboratories in
the same year. While trying to design a vacuum tube that could
amplify current, it occurred to him that solid state components
might work better than the fragile tubes. He experimented with
the semiconductors germanium and silicon, but the materials
available were too impure for his purpose. World War II interrupted
the experiments, and he worked instead to improve radar
and anti-submarine devices for the military. Back at Bell
Labs in 1945, Shockley teamed with theorist John Bardeen and
experimentalist Walter Brattain. Two years later they succeeded
in making the first amplifier out of semiconductor materials
and called it a transistor (short for transfer resistor). Its effect on
the electronics industry was revolutionary, and the three shared
the 1956 Nobel Prize in Physics for their achievement.
In the mid-1950’s Shockley left Bell Labs to start Shockley
Transistor, then switched to academia in 1963, becoming Stanford
University’s Alexander M. Poniatoff Professor of Engineering
and Applied Science. He grew interested in the relation
between race and intellectual ability. Teaching himself psychology
and genetics, he conceived the theory that Caucasians were
inherently more intelligent than other races because of their genetic
make-up. When he lectured on his brand of eugenics, he
was denounced by the public as a racist and by scientists for
shoddy thinking. Shockley retired in 1975 and died in 1989.

Transistor / 783
American living room and used the same vacuum tube amplification
unit. The transistorized portable television set did for images
what the transistor radio did for sound. Sony was the first to develop
an all-transistor television, in 1959. At a time when the trend
in television receivers was toward larger screens, Sony produced
extremely small models with eight-inch screens. Ignoring the marketing
experts who said that Americans would never buy such a
product, Sony introduced these models into the United States in
1960 and found that there was a huge demand for them.
As in radio, the number of television stations on the air and
broadcasts for the viewer to choose from grew. Apersonal television
or radio gave the audience more choices. Instead of one machine in
the family room, there were now several around the house. The
transistorization of mechanical entertainers allowed each family
member to choose his or her own entertainment. Sony learned several
important lessons from the success of the transistor radio and
television. The first was that small size and low price could create
new markets for electronic consumer products. The second was that
constant innovation and cost reduction were essential to keep ahead
of the numerous companies that produced cheaper copies of original
Sony products.
In 1962, Sony introduced a tiny television receiver with a fiveinch
screen. In the 1970’s and 1980’s, it produced even smaller models,
until it had a TV set that could sit in the palm of the hand—the
Video Walkman. Sony’s scientists had developed an entirely new
television screen that worked on a new principle and gave better
color resolution; the company was again able to blend the fruits of
basic scientific research with innovative industrial engineering.
The transistorized amplifier unit used in radio and television sets
was applied to other products, including amplifiers for record players
and tape recorders. Japanese manufacturers were slow to take
part in the boom in high-fidelity audio equipment that began in the
United States in the 1950’s. The leading manufacturers of highquality
audio components were small American companies based
on the talents of one engineer, such as Avery Fisher or Henry Koss.
They sold expensive amplifiers and loudspeakers to audiophiles.
The transistor reduced the size, complexity, and price of these components.
The Japanese took the lead devising complete audio units

784 / Transistor
based on transistorized integrated circuits, thus developing the basic
home stereo.
In the 1960’s, companies such as Sony and Matsushita dominated
the market for inexpensive home stereos. These were the basic
radio/phonograph combination, with two detached speakers.
The finely crafted wooden consoles that had been the standard for
the home phonograph were replaced by small plastic boxes. The
Japanese were also quick to exploit the opportunities of the tape cassette.
The Philips compact cassette was enthusiastically adopted by
Japanese manufacturers and incorporated into portable tape recorders.
This was another product with its ancestry in the transistor
radio. As more of them were sold, the price dropped, encouraging
more consumers to buy. The cassette player became as commonplace
in American society in the 1970’s as the transistor radio had
been in the 1960’s.
The Walkman
The transistor took another step in miniaturization in the Sony
Walkman, a personal stereo sound system consisting of a cassette
player and headphones. It was based on the same principles as the
transistor radio and television. Sony again confounded marketing
experts by creating a new market for a personal electronic entertainer.
In the ten years following the introduction of the Walkman in
1979, Sony sold fifty million units worldwide, half of those in the
United States. Millions of imitation products were sold by other
companies.
Sony’s acquisition of the Western Electric transistor technology
was a turning point in the fortunes of that company and of Japanese
manufacturers in general. Less than ten years after suffering defeat
in a disastrous war, Japanese industry served notice that it had lost
none of its engineering capabilities and innovative skills. The production
of the transistor radio was a testament to the excellence of
Japanese research and development. Subsequent products proved
that the Japanese had an uncanny sense of the potential market for
consumer products based on transistor technology. The ability to incorporate
solid-state electronics into innovative home entertainment
products allowed Japanese manufacturers to dominate the

world market for electronic consumer products and to eliminate
most of their American competitors.
The little transistor radio was the vanguard of an invasion of new
products unparalleled in economic history. Japanese companies
such as Sony and Panasonic later established themselves at the leading
edge of digital technology, the basis of a new generation of entertainment
products. Instead of Japanese engineers scraping together
the money to buy a license for an American technology, the
great American companies went to Japan to license compact disc
and other digital technologies.
See also Cassette recording; Color television; FM radio; Radio;
Television; Transistor radio; Videocassette recorder; Walkman cassette
player.
Further Reading
Transistor / 785
Lyons, Nick. The Sony Vision. New York: Crown Publishers, 1976.
Marshall, David V. Akio Morita and Sony. Watford: Exley, 1995.
Morita, Akio, with Edwin M. Reingold, and Mitsuko Shimomura.
Made in Japan: Akio Morita and Sony. London: HarperCollins,
1994.
Reid, T. R. The Chip: How Two Americans Invented the Microchip and
Launched a Revolution. New York: Simon and Schuster, 1984.
Riordan, Michael. Crystal Fire: The Invention of the Transistor and the
Birth of the Information Age. New York: Norton, 1998.
Scott, Otto. The Creative Ordeal: The Story of Raytheon. New York:
Atheneum, 1974.

786
Transistor radio
Transistor radio
The invention: Miniature portable radio that used transistors and
created a new mass market for electronic products.
The people behind the invention:
John Bardeen (1908-1991), an American physicist
Walter H. Brattain (1902-1987), an American physicist
William Shockley (1910-1989), an American physicist
Akio Morita (1921-1999), a Japanese physicist and engineer
Masaru Ibuka (1907-1997), a Japanese electrical engineer and
industrialist
A Replacement for Vacuum Tubes
The invention of the first transistor by William Shockley, John
Bardeen, and Walter H. Brattain of Bell Labs in 1947 was a scientific
event of great importance. Its commercial importance at the time,
however, was negligible. The commercial potential of the transistor
lay in the possibility of using semiconductor materials to carry out
the functions performed by vacuum tubes, the fragile and expensive
tubes that were the electronic hearts of radios, sound amplifiers,
and telephone systems. Transistors were smaller, more rugged,
and less power-hungry than vacuum tubes. They did not suffer
from overheating. They offered an alternative to the unreliability
and short life of vacuum tubes.
Bell Labs had begun the semiconductor research project in an effort
to find a better means of electronic amplification. This was
needed to increase the strength of telephone signals over long distances.
Therefore, the first commercial use of the transistor was
sought in speech amplification, and the small size of the device
made it a perfect component for hearing aids. Engineers from the
Raytheon Company, the leading manufacturer of hearing aids, were
invited to Bell Labs to view the new transistor and to help assess the
commercial potential of the technology. The first transistorized consumer
product, the hearing aid, was soon on the market. The early
models built by Raytheon used three junction-type transistors and
cost more than two hundred dollars. They were small enough to go

directly into the ear or to be incorporated into eyeglasses.
The commercial application of semiconductors was aimed largely
at replacing the control and amplification functions carried out by
vacuum tubes. The perfect vehicle for this substitution was the radio
set. Vacuum tubes were the most expensive part of a radio set
and the most prone to break down. The early junction transistors
operated best at low frequencies, and subsequently more research
was needed to produce a commercial high-frequency transistor.
Several of the licensees embarked on this quest, including the Radio
Corporation of America (RCA), Texas Instruments, and the Tokyo
Telecommunications Engineering Company of Japan.
Perfecting the Transistor
Transistor radio / 787
The Tokyo Telecommunications Engineering Company of Japan,
formed in 1946, had produced a line of instruments and consumer
products based on vacuum-tube technology. Its most successful
product was a magnetic tape recorder. In 1952, one of the founders
of the company, Masaru Ibuka, visited the United States to learn
more about the use of tape recorders in schools and found out that
Western Electric was preparing to license the transistor patent. With
only the slightest understanding of the workings of semiconductors,
Tokyo Telecommunications purchased a license in 1954 with
the intention of using transistors in a radio set.
The first task facing the Japanese was to increase the frequency
response of the transistor to make it suitable for radio use. Then a
method of manufacturing transistors cheaply had to be found. At
the time, junction transistors were made from slices of germanium
crystal. Growing the crystal was not an exact science, nor was the
process of “doping” it with impurities to form the different layers of
conductivity that made semiconductors useful. The Japanese engineers
found that the failure rate for high-frequency transistors was
extremely high. The yield of good transistors from one batch ran as
low as 5 percent, which made them extremely expensive and put the
whole project in doubt. The effort to replace vacuum tubes with
components made of semiconductors was motivated by cost rather
than performance; if transistors proved to be more expensive, then
it was not worth using them.

788 / Transistor radio
Engineers from Tokyo Telecommunications again came to the
United States to search for information about the production of
transistors. In 1954, the first high-frequency transistor was produced
in Japan. The success of Texas Instruments in producing the
components for the first transistorized radio (introduced by the Regency
Company in 1954) spurred the Japanese to greater efforts.
Much of their engineering and research work was directed at the
manufacture and quality control of transistors. In 1955, they introduced
their transistor radio, the TR-55, which carried the brand
name “Sony.” The name was chosen because the executives of the
company believed that the product would have an international appeal
and therefore needed a brand name that could be recognized
easily and remembered in many languages. In 1957, the name of the
entire company was changed to Sony.
Impact
Although Sony’s transistor radios were successful in the marketplace,
they were still relatively large and cumbersome. Ibuka saw a
consumer market for a miniature radio and gave his engineers the
task of designing a radio small enough to fit into a shirt pocket. The
realization of this design—“Transistor Six”—was introduced in 1957.
It was an immediate success. Sony sold the radios by the millions,
and numerous imitations were also marketed under brand names
such as “Somy” and “Sonny.” The product became an indispensable
part of popular culture of the late 1950’s and 1960’s; its low cost enabled
the masses to enjoy radio wherever there were broadcasts.
The pocket-sized radio was the first of a line of electronic consumer
products that brought technology into personal contact with
the user. Sony was convinced that miniaturization did more than
make products more portable; it established a one-on-one relationship
between people and machines. Sony produced the first alltransistor
television in 1960. Two years later, it began to market a
miniature television in the United States. The continual reduction in
the size of Sony’s tape recorders reached a climax with the portable
tape player introduced in the 1980’s. The Sony Walkman was a marketing
triumph and a further reminder that Japanese companies led
the way in the design and marketing of electronic products.

John Bardeen
Transistor radio / 789
The transistor reduced the size of electronic circuits and at
the same time the amount of energy lost from them as heat.
Superconduction gave rise to electronic circuits with practically
no loss of energy at all. John Bardeen helped unlock the secrets
of both.
Bardeen was born in 1908 in Madison, Wisconsin, where his
mother was an artist and his father was a professor of anatomy
at the University of Wisconsin. Bardeen attended the university,
earning a bachelor’s degree in electrical engineering in 1928
and a master’s degree in geophysics in 1929. After working as a
geophysicist, he entered Princeton University, studying with
Eugene Wigner, the leading authority on solid-state physics,
and received a doctorate in mathematics and physics in 1936.
Bardeen taught at Harvard University and the University of
Minnesota until World War II, when he moved to the Naval
Ordnance Laboratory. Finding academic salaries too low to
support his family after the war, he accepted a position at Bell
Telephone Laboratories. There, with Walter Brattain, he turned
William Shockley’s theory of semiconductors into a practical
device—the transfer resistor, or transistor.
He returned to academia as a professor at the University of
Illinois and began to investigate a long-standing mystery in
physics, superconductivity, with a postdoctoral associate, Leon
Cooper, and a graduate student, J. Robert Schrieffer. In 1956
Cooper made a key discovery—superconducting electrons
travel in pairs. And while Bardeen was in Stockholm, Sweden,
collecting a share of the 1956 Nobel Prize in Physics for his work
on transistors, Schrieffer worked out a mathematical analysis of
the phenomenon. The theory that the three men published since
became known as BCS theory from the first letters of their last
names, and as well as explain superconductors, it pointed toward
a great deal of technology and additional basic research.
The team won the 1972 Nobel Prize in Physics for BCS theory,
making Bardeen the only person to ever win two Nobel Prizes
for physics. He retired in 1975 and died sixteen years later.
See also Compact disc; FM radio; Radio; Radio crystal sets; Television;
Transistor; Walkman cassette player.

790 / Transistor radio
Further Reading
Handy, Roger, Maureen Erbe, and Aileen Antonier. Made in Japan:
Transistor Radios of the 1950s and 1960s. San Francisco: Chronicle
Books, 1993.
Marshall, David V. Akio Morita and Sony. Watford: Exley, 1995.
Morita, Akio, with Edwin M. Reingold, and Mitsuko Shimomura.
Made in Japan: Akio Morita and Sony. London: HarperCollins, 1994.
Nathan, John. Sony: The Private Life. London: HarperCollins-
Business, 2001.

Tuberculosis vaccine
Tuberculosis vaccine
The invention: Vaccine that uses an avirulent (nondisease) strain
of bovine tuberculosis bacilli that is safer than earlier vaccines.
The people behind the invention:
Albert Calmette (1863-1933), a French microbiologist
Camille Guérin (1872-1961), a French veterinarian and
microbiologist
Robert Koch (1843-1910), a German physician and
microbiologist
Isolating Bacteria
791
Tuberculosis, once called “consumption,” is a deadly, contagious
disease caused by the bacterium Mycobacterium tuberculosis,
first identified by the eminent German physician Robert Koch in
1882. The bacterium can be transmitted from person to person by
physical contact or droplet infection (for example, sneezing). The
condition eventually inflames and damages the lungs, causing difficulty
in breathing and failure of the body to deliver sufficient oxygen
to various tissues. It can spread to other body tissues, where
further complications develop. Without treatment, the disease progresses,
disabling and eventually killing the victim. Tuberculosis
normally is treated with a combination of antibiotics and other
drugs.
Koch developed his approach for identifying bacterial pathogens
(disease producers) with simple equipment, primarily microscopy.
Having taken blood samples from diseased animals, he would
identify and isolate the bacteria he found in the blood. Each strain of
bacteria would be injected into a healthy animal. The latter would
then develop the disease caused by the particular strain.
In 1890, he discovered that a chemical released from tubercular
bacteria elicits a hypersensitive (allergic) reaction in individuals
previously exposed to or suffering from tuberculosis. This chemical,
called “tuberculin,” was isolated from culture extracts in which tubercular
bacteria were being grown.

792 / Tuberculosis vaccine
When small amounts of tuberculin are injected into a person subcutaneously
(beneath the skin), a reddened, inflamed patch approximately
the size of a quarter develops if the person has been exposed
to or is suffering from tuberculosis. Injection of tuberculin into an
uninfected person yields a negative response (that is, no inflammation).
Tuberculin does not harm those being tested.
Tuberculosis’s Weaker Grandchildren
The first vaccine to prevent tuberculosis was developed in 1921
by two French microbiologists, Albert Calmette and Camille Guérin.
Calmette was a student of the eminent French microbiologist Louis
Pasteur at Pasteur’s Institute in Paris. Guérin was a veterinarian
who joined Calmette’s laboratory in 1897. At Lille, Calmette and
Guérin focused their research upon the microbiology of infectious
diseases, especially tuberculosis.
In 1906, they discovered that individuals who had been exposed to
tuberculosis or who had mild infections were developing resistance to
the disease. They found that resistance to tuberculosis was initiated by
the body’s immune system. They also discovered that tubercular bacteria
grown in culture over many generations become progressively
weaker and avirulent, losing their ability to cause disease.
From 1906 through 1921, Calmette and Guérin cultured tubercle
bacilli from cattle. With proper nutrients and temperature, bacteria
can reproduce by fission (that is, one bacterium splits into two bacteria)
in as little time as thirty minutes. Calmette and Guérin cultivated
these bacteria in a bile-derived food medium for thousands of
generations over fifteen years, periodically testing the bacteria for
virulence by injecting them into cattle. After many generations, the
bacteria lost their virulence, their ability to cause disease. Nevertheless,
these weaker, or “avirulent” bacteria still stimulated the animals’
immune systems to produce antibodies. Calmette and Guérin
had successfully bred a strain of avirulent bacteria that could not
cause tuberculosis in cows but could also stimulate immunity against
the disease.
There was considerable concern over whether the avirulent strain
was harmless to humans. Calmette and Guérin continued cultivating
weaker versions of the avirulent strain that retained antibody-

stimulating capacity. By 1921, they had isolated an avirulent antibody-stimulating
strain that was harmless to humans, a strain they
called “Bacillus Calmette-Guérin” (BCG).
In 1922, they began BCG-vaccinating newborn children against
tuberculosis at the Charité Hospital in Paris. The immunized children
exhibited no ill effects from the BCG vaccination. Calmette and
Guérin’s vaccine was so successful in controlling the spread of tuberculosis
in France that it attained widespread use in Europe and
Asia beginning in the 1930’s.
Impact
Tuberculosis vaccine / 793
Most bacterial vaccines involve the use of antitoxin or heat- or
chemical-treated bacteria. BCG is one of the few vaccines that use
specially bred live bacteria. Its use sparked some controversy in
the United States and England, where the medical community
questioned its effectiveness and postponed BCG immunization
until the late 1950’s. Extensive testing of the vaccine was performed
at the University of Illinois before it was adopted in the
United States. Its effectiveness is questioned by some physicians to
this day.
Some of the controversy stems from the fact that the avirulent,
antibody-stimulating BCG vaccine conflicts with the tuberculin
skin test. The tuberculin skin test is designed to identify people
suffering from tuberculosis so that they can be treated. A BCGvaccinated
person will have a positive tuberculin skin test similar
to that of a tuberculosis sufferer. If a physician does not know that
a patient has had a BCG vaccination, it will be presumed (incorrectly)
that the patient has tuberculosis. Nevertheless, the BCG
vaccine has been invaluable in curbing the worldwide spread of
tuberculosis, although it has not eradicated the disease.
See also Antibacterial drugs; Birth control pill; Penicillin; Polio
vaccine (Sabin); Polio vaccine (Salk); Salvarsan; Typhus vaccine;
Yellow fever vaccine.

794 / Tuberculosis vaccine
Further Reading
Daniel, Thomas M. Pioneers of Medicine and their Impact on Tuberculosis.
Rochester, N.Y.: University of Rochester Press, 2000.
DeJauregui, Ruth. 100 Medical Milestones That Shaped World History.
San Mateo, Calif.: Bluewood Books, 1998.
Fry, William F. “Prince Hamlet and Professor Koch.” Perspectives in
Biology and Medicine 40, no. 3 (Spring, 1997).
Lutwick, Larry I. New Vaccines and New Vaccine Technology. Philadelphia:
Saunders, 1999.

Tungsten filament
Tungsten filament
The invention: Metal filament used in the incandescent light bulbs
that have long provided most of the world’s electrical lighting.
The people behind the invention:
William David Coolidge (1873-1975), an American electrical
engineer
Thomas Alva Edison (1847-1931), an American inventor
The Incandescent Light Bulb
The electric lamp developed along with an understanding of
electricity in the latter half of the nineteenth century. In 1841, the
first patent for an incandescent lamp was granted in Great Britain. A
patent is a legal claim that protects the patent holder for a period of
time from others who might try to copy the invention and make a
profit from it. Although others tried to improve upon the incandescent
lamp, it was not until 1877, when Thomas Alva Edison, the famous
inventor, became interested in developing a successful electric
lamp, that real progress was made. The Edison Electric Light
Company was founded in 1878, and in 1892, it merged with other
companies to form the General Electric Company.
Early electric lamps used platinum wire as a filament. Because
platinum is expensive, alternative filament materials were sought.
After testing many substances, Edison finally decided to use carbon
as a filament material. Although carbon is fragile, making it difficult
to manufacture filaments, it was the best choice available at the time.
The Manufacture of Ductile Tungsten
795
Edison and others had tested tungsten as a possible material for
lamp filaments but discarded it as unsuitable. Tungsten is a hard,
brittle metal that is difficult to shape and easy to break, but it possesses
properties that are needed for lamp filaments. It has the highest
melting point (3,410 degrees Celsius) of any known metal; therefore,
it can be heated to a very high temperature, giving off a

796 / Tungsten filament
relatively large amount of radiation without melting (as platinum
does) or decomposing (as carbon does). The radiation it emits when
heated is primarily visible light. Its resistance to the passage of electricity
is relatively high, so it requires little electric current to reach
its operating voltage. It also has a high boiling point (about 5,900 degrees
Celsius) and therefore does not tend to boil away, or vaporize,
when heated. In addition, it is mechanically strong, resisting breaking
caused by mechanical shock.
William David Coolidge, an electrical engineer with the General
Electric Company, was assigned in 1906 the task of transforming
tungsten from its natural state into a form suitable for lamp filaments.
The accepted procedure for producing fine metal wires was
(and still is) to force a wire rod through successively smaller holes in
a hard metal block until a wire of the proper diameter is achieved.
The property that allows a metal to be drawn into a fine wire by
means of this procedure is called “ductility.” Tungsten is not naturally
ductile, and it was Coolidge’s assignment to make it into a ductile
form. Over a period of five years, and after many failures, Coolidge
and his workers achieved their goal. By 1911, General Electric
was selling lamps that contained tungsten filaments.
Originally, Coolidge attempted to mix powdered tungsten with a
suitable substance, form a paste, and squirt that paste through a die
to form the wire. The paste-wire was then sintered (heated at a temperature
slightly below its melting point) in an effort to fuse the
powder into a solid mass. Because of its higher boiling point, the
tungsten would remain after all the other components in the paste
boiled away. At about 300 degrees Celsius, tungsten softens sufficiently
to be hammered into an elongated form. Upon cooling, however,
tungsten again becomes brittle, which prevents it from being
shaped further into filaments. It was suggested that impurities in
the tungsten caused the brittleness, but specially purified tungsten
worked no better than the unpurified form.
Many metals can be reduced from rods to wires if the rods are
passed through a series of rollers that are successively closer together.
Some success was achieved with this method when the rollers
were heated along with the metal, but it was still not possible to
produce sufficiently fine wire. Next, Coolidge tried a procedure
called “swaging,” in which a thick wire is repeatedly and rapidly

struck by a series of rotating hammers as the wire is drawn past
them. After numerous failures, a fine wire was successfully produced
using this procedure. It was still too thick for lamp filaments,
but it was ductile at room temperature.
Microscopic examination of the wire revealed a change in the
crystalline structure of tungsten as a result of the various treatments.
The individual crystals had elongated, taking on a fiberlike
appearance. Now the wire could be drawn through a die to achieve
the appropriate thickness. Again, the wire had to be heated, and if
the temperature was too high, the tungsten reverted to a brittle
state. The dies themselves were heated, and the reduction progressed
in stages, each of which reduced the wire’s diameter by a
thousandth of an inch.
Finally, Coolidge had been successful. Pressed tungsten bars
measuring 1 4 × 3 8 × 6 inches were hammered and rolled into rods 1 8
inch, or 125 1000 inch, in diameter. The unit 1 1000 inch is often called a
“mil.” These rods were then swaged to approximately 30 mil and
then passed through dies to achieve the filament size of 25 mil or
smaller, depending on the power output of the lamp in which the
filament was to be used. Tungsten wires of 1 mil or smaller are now
readily available.
Impact
Tungsten filament / 797
Ductile tungsten wire filaments are superior in several respects
to platinum, carbon, or sintered tungsten filaments. Ductile filament
lamps can withstand more mechanical shock without breaking.
This means that they can be used in, for example, automobile
headlights, in which jarring frequently occurs. Ductile wire can also
be coiled into compact cylinders within the lamp bulb, which makes
for a more concentrated source of light and easier focusing. Ductile
tungsten filament lamps require less electricity than do carbon filament
lamps, and they also last longer. Because the size of the filament
wire can be carefully controlled, the light output from lamps
of the same power rating is more reproducible. One 60-watt bulb is
therefore exactly like another in terms of light production.
Improved production techniques have greatly reduced the cost
of manufacturing ductile tungsten filaments and of light-bulb man-

798 / Tungsten filament
ufacturing in general. The modern world is heavily dependent
upon this reliable, inexpensive light source, which turns darkness
into daylight.
See also Fluorescent lighting; Memory metal; Steelmaking
process.
Further Reading
Baldwin, Neil. Edison: Inventing the Century. Chicago: University of
Chicago Press, 2001.
Cramer, Carol. Thomas Edison. San Diego, Calif.: Greenhaven Press,
2001.
Israel, Paul. Edison: A Life of Invention. New York: John Wiley, 1998.
Liebhafsky, H. A. William David Coolidge: A Centenarian and His Work.
New York: Wiley, 1974.
Miller, John A. Yankee Scientist: William David Coolidge. Schenectady,
N.Y.: Mohawk Development Service, 1963.

Tupperware
Tupperware
The invention: Trademarked food-storage products that changed
the way Americans viewed plastic products and created a model
for selling products in consumers’ homes.
The people behind the invention:
Earl S. Tupper (1907-1983), founder of Tupperware
Brownie Wise, the creator of the vast home sales network for
Tupperware
Morison Cousins (1934-2001), a designer hired by Tupperware
to modernize its products in the early 1990’s
“The Wave of the Future”?
799
Relying on a belief that plastic was the wave of the future and
wanting to improve on the newest refrigeration technology, Earl S.
Tupper, who called himself “a ham inventor and Yankee trader,”
created an empire of products that changed America’s kitchens.
Tupper, a self-taught chemical engineer, began working at Du Pont
in the 1930’s. This was a time of important developments in the
field of polymers and the technology behind plastics. Wanting to
experiment with this new material yet unable to purchase the
needed supplies, Tupper went to his employer for help. Because of
the limited availability of materials, major chemical companies
had been receiving all the raw goods for plastic production. Although
Du Pont would not part with raw materials, the company
was willing to let Tupper have the slag.
Polyethylene slag was a black, rock-hard, malodorous waste
product of oil refining. It was virtually unusable. Undaunted,
Tupper developed methods to purify the slag. He then designed
an injection molding machine to form bowls and other containers
out of his “Poly-T.” Tupper did not want to call the substance plastic
because of a public distrust of that substance. In 1938, he
founded the Tupper Plastics Company to pursue his dream. It was
during those first years that he formulated the design for the famous
Tupperware seal.

800 / Tupperware
Refrigeration techniques had improved tremendously during
the first part of the twentieth century. The iceboxes in use prior to
the 1940’s were inconsistent in their interior conditions and were
usually damp inside because of melting of the ice. In addition, the
metal, glass, or earthenware food storage containers used during
the first half of the century did not seal tightly and allowed food to
stay moist. Iceboxes allowed mixing of food odors, particularly evident
with strong-smelling items such as onions and fish.
Electric Refrigerators
In contrast to iceboxes, the electric refrigerators available starting
in the 1940’s maintained dry interiors and low temperatures. This
change in environment resulted in food drying out and wilting.
Tupper set out to alleviate this problem through his plastic containers.
The key to Tupper’s solution was his containers’ seal. He took
his design from paint can lids and inverted it. This tight seal created
a partial vacuum that protected food from the dry refrigeration process
and kept food odors sealed within containers.
In 1942, Tupper bought his first manufacturing plant, in Farnumsville,
Massachusetts. There he continued to improve on his designs.
In 1945, Tupper introduced Tupperware, selling it through
hardware and department stores as well as through catalog sales.
Tupperware products were made of flexible, translucent plastic.
Available in frosted crystal and five pastel colors, the new containers
were airtight and waterproof. In addition, they carried a lifetime
warranty against chipping, cracking, peeling, and breaking in normal
noncommercial use. Early supporters of Tupperware included
the American Thermos Bottle Company, which purchased seven
million nesting cups, and the Tek Corporation, which ordered fifty
thousand tumblers to sell with toothbrushes.
Even though he benefited from this type of corporate support,
Tupper wanted his products to be for home use. Marketing the new
products proved to be difficult in the early years. Tupperware sat on
hardware and department store shelves, and catalog sales were
nearly nonexistent. The problem appeared to involve a basic distrust
of plastic by consumers and an unfamiliarity with how to use
the new products. The product did not come with instructions on

how to seal the containers or descriptions of how the closed container
protected the food within. Brownie Wise, an early direct seller
and veteran distributor of Stanley Home Products, stated that it
took her several days to understand the technology behind the seal
and the now-famous Tupperware “burp,” the sound made when air
leaves the container as it seals.
Wise and two other direct sellers, Tom Damigella and Harvey
Hollenbush, found the niche for selling Tupperware for daily use—
home sales. Wise approached Tupper with a home party sales strategy
and detailed how it provided a relaxed atmosphere in which to
learn about the products and thus lowered sales resistance. In April,
1951, Tupper took his product off store shelves and hired Wise to
create a new direct selling system under the name of Tupperware
Home Parties, Inc.
Impact
Tupperware / 801
Home sales had already proved to be successful for the Fuller
Brush Company and numerous encyclopedia publishers, yet Brownie
Wise wanted to expand the possibilities. Her first step was to found
a campus-like headquarters in Kissimmee, Florida. There, Tupper and
a design department worked to develop new products, and Tupperware
Home Parties, Inc., under Wise’s direction, worked to develop
new incentives for Tupperware’s direct sellers, called hostesses.
Wise added spark to the notion of home demonstrations. “Parties,”
as they were called, included games, recipes, giveaways, and other
ideas designed to help housewives learn how to use Tupperware
products. The marketing philosophy was to make parties appealing
events at which women could get together while their children were
in school. This fit into the suburban lifestyle of the 1950’s. These parties
offered a nonthreatening means for home sales representatives
to attract audiences for their demonstrations and gave guests a chance
to meet and socialize with their neighbors. Often compared to
the barbecue parties of the 1950’s, Tupperware parties were social,
yet educational, affairs. While guests ate lunch or snacked on desserts,
the Tupperware hostess educated them about the technology
behind the bowls and their seals as well as suggesting a wide variety
of uses for the products. For example, a party might include

802 / Tupperware
recipes for dinner parties, with information provided on how
party leftovers could be stored efficiently and economically with
Tupperware products.
While Tupperware products were changing the kitchens of America,
they were also changing the women who sold them (almost all the
hosts were women). Tupperware sales offered employment for women
at a time when society disapproved of women working outside the
home. Being a hostess, however, was not a nine-to-five position. The
job allowed women freedom to tailor their schedules to meet family
needs. Employment offered more than the economic incentive of 35
percent of gross sales. Hostesses also learned new skills and developed
self-esteem. An acclaimed mentoring program for new and advancing
employees provided motivational training. Managers came only from
the ranks of hostesses; moving up the corporate ladder meant spending
time selling Tupperware at home parties.
The opportunity to advance offered incentive. In addition, annual
sales conventions were renowned for teaching new marketing
strategies in fun-filled classes. These conventions also gave women
an opportunity to network and establish contacts. These experiences
proved to be invaluable as women entered the workforce in
increasing numbers in later decades.
Expanding Home-Sales Business
The tremendous success of Tupperware’s marketing philosophy
helped to set the stage for other companies to enter home sales.
These companies used home-based parties to educate potential customers
in familiar surroundings, in their own homes or in the
homes of friends. The Mary Kay Cosmetics Company, founded in
1963, used beauty makeovers in the home party setting as its chief
marketing tool. Discovery Toys, founded in 1978, encouraged guests
to get on the floor and play with the toys demonstrated at its home
parties. Both companies extended the socialization aspects found in
Tupperware parties.
In addition to setting the standard for home sales, Tupperware
is also credited with starting the plastic revolution. Early plastics
were of poor quality and cracked or broke easily. This created distrust
of plastic products among consumers. Earl Tupper’s demand

Tupperware / 803
for quality set the stage for the future of plastics. He started with
high-quality resin and developed a process that kept the “Poly-T”
from splitting. He then invented an injection molding machine that
mass-produced his bowl and cup designs. His standards of quality
from start to finish helped other companies expand into plastics.
The 1950’s saw a wide variety of products appear in the improved
material, including furniture and toys. This shift from wood, glass,
and metal to plastic continued for decades.
Maintaining the position of Tupperware within the housewares
Earl S. Tupper
Born in 1907, Earl Silas Tupper came from a family of go-getters.
His mother, Lulu Clark Tupper, kept a boardinghouse and
took in laundry, while his father, Earnest, ran a small farm and
greenhouse in New Hampshire. The elder Tupper was also a
small-time inventor, patenting a device for stretching out chickens
to make cleaning them easier. Earl absorbed the family’s
taste for invention and enterprise.
Fresh out of high school in 1925, Tupper vowed to turn himself
into a millionaire by the time he was thirty. He started a
landscaping and nursery business in 1928, but the Depression
led his company, Tupper Tree, into bankruptcy in 1936. Tupper
was undeterred. He hired on with Du Pont the next year. Du
Pont taught him a great deal about the chemistry and manufacturing
of plastics, but it did not give him scope to apply his
ideas, so in 1938 he founded the Earl S. Tupper Company. He
continued to work as a contractor for Du Pont to make the
fledgling company profitable, and during World War II the
company made plastic moldings for gas masks and Navy signal
lamps. Finally, in the 1940’s Tupper could devote himself to
his dream—designing plastic food containers, cups, and such
small household conveniences as cases for cigarette packs.
Thanks to aggressive, innovative direct marketing, Tupper’s
kitchenware, Tupperware, became synonymous with plastic
containers during the 1950’s. In 1958 Tupper sold his company
to Rexall for $16 million, having finally realized his youthful
ambition to make himself wealthy through Yankee wit and
hard work. He died in 1983.

804 / Tupperware
market meant keeping current. As more Americans were able to purchase
the newest refrigerators, Tupperware expanded to meet their
needs. The company added new products, improved marketing
strategies, and changed or updated designs. Over the years, Tupperware
added baking items, toys, and home storage containers for such
items as photographs, sewing materials, and holiday ornaments. The
1980’s and 1990’s brought microwaveable products.
As women moved into the work force in great numbers, Tupperware
moved with them. The company introduced lunchtime parties
at the workplace and parties at daycare centers for busy working
parents. Tupperware also started a fund-raising line, in special colors,
that provided organizations with a means to bring in money
while not necessitating full-fledged parties. New party themes developed
around time-saving techniques and health concerns such
as diet planning. Beginning in 1992, customers too busy to attend a
party could call a toll-free number, request a catalog, and be put in
contact with a “consultant,” as “hostesses” now were called.
Another marketing strategy developed out of a public push for
environmentally conscious products. Tupperware consultants stressed
the value of buying food in bulk to create less trash as well as saving
money. To store these increased purchases, the company developed
a new line for kitchen staples called Modular Mates. These stackable
containers came in a wide variety of shapes and sizes to hold everything
from cereal to flour to pasta. They were made of see-through
plastic, allowing the user to see if the contents needed replenishing.
Some consultants tailored parties around ideas to better organize
kitchen cabinets using the new line. Another environmentally conscious
product idea was the Tupperware lunch kit. These kits did
away with the need for throwaway products such as paper plates,
plastic storage bags, and aluminum foil. Lunch kits marketed in
other countries were developed to accommodate the countries’ particular
needs. For example, Japanese designs included chopsticks,
while Latin American styles were designed to hold tortillas.
Design Changes
Tupperware designs have been well received over the years.
Early designs prompted a 1947 edition of House Beautiful to call the

Tupperware / 805
product “Fine Art for 39 cents.” Fifteen of Tupper’s earliest designs
are housed in a permanent collection at the Museum of Modern Art
in New York City. Other museums, such as the Metropolitan Museum
of Art and the Brooklyn Museum, also house Tupperware designs.
Tupperware established its own Museum of Historic Food
Containers at its international headquarters in Florida. Despite this
critical acclaim, the company faced a constant struggle to keep
product lines competitive with more accessible products, such as
those made by Rubbermaid, that could be found on the shelves of
local grocery or department stores.
Some of the biggest design changes came with the hiring of
Morison Cousins in the early 1990’s. Cousins, an accomplished designer,
set out to modernize the Tupperware line. He sought to return
to simple, traditional styles while bringing in time-saving aspects.
He changed lid designs to make them easier to clean and
rounded the bottoms of bowls so that every portion could be scooped
out. Cousins also added thumb handles to bowls.
Backed by a knowledgeable sales force and quality product, the
company experienced tremendous growth. Tupperware sales reached
$25 million in 1954. By 1958, the company had grown from seven
distributorships to a vast system covering the United States and
Canada. That same year, Brownie Wise left the company, and Tupper
Plastics was sold to Rexall Drug Company for $9 million. Rexall
Drug changed its name to Dart Industries, Inc., in 1969, then merged
with Kraft, Inc., eleven years later to become Dart and Kraft, Inc.
During this time of parent-company name changing, Tupperware
continued to be an important subsidiary. Through the 1960’s and
1970’s, the company spread around the world, with sales in Western
Europe, the Far East, and Latin America. In 1986, Dart and Kraft,
Inc., split into Kraft, Inc., and Premark International, Inc., of which
Dart (and therefore Tupperware) was a subsidiary. Premark International
included other home product companies such as West
Bend, Precor, and Florida Tile.
By the early 1990’s, annual sales of Tupperware products reached
$1.1 billion. Manufacturing plants in Halls, Tennessee, and Hemingway,
South Carolina, worked to meet the high demand for Tupperware
products in more than fifty countries. Foreign sales accounted
for almost 75 percent of the company’s business. By meeting the

806 / Tupperware
needs of consumers and keeping current with design changes, new
sales techniques, and new products, Tupperware was able to reach
90 percent of America’s homes.
See also Electric refrigerator; Food freezing; Freeze-drying; Microwave
cooking; Plastic; Polystyrene; Pyrex glass; Teflon.
Further Reading
Brown, Patricia Leigh. “New Designs to Keep Tupperware Fresh.”
New York Times (June 10, 1993).
Clarke, Alison J. Tupperware: The Promise of Plastic in 1950s America.
Washington, D.C.: Smithsonian Institution Press, 1999.
Gershman, Michael. Getting It Right the Second Time. Reading, Mass.:
Addison-Wesley, 1990.
Martin, Douglas. “Morison S. Cousins, Sixty-six, Designer, Dies; Revamped
Tupperware’s Look with Flair.” New York Times (February
18, 2001).
Sussman, Vic. “I Was the Only Virgin at the Party.” Sales and Marketing
Management 141 (September 1, 1989).

Turbojet
Turbojet
The invention: A jet engine with a turbine-driven compressor that
uses its hot-gas exhaust to develop thrust.
The people behind the invention:
Henry Harley Arnold (1886-1950), a chief of staff of the U.S.
Army Air Corps
Gerry Sayer, a chief test pilot for Gloster Aircraft Limited
Hans Pabst von Ohain (1911- ), a German engineer
Sir Frank Whittle (1907-1996), an English Royal Air Force
officer and engineer
Developments in Aircraft Design
807
On the morning of May 15, 1941, some eleven months after
France had fallen to Adolf Hitler’s advancing German army, an experimental
jet-propelled aircraft was successfully tested by pilot
Gerry Sayer. The airplane had been developed in a little more than
two years by the English company Gloster Aircraft under the supervision
of Sir Frank Whittle, the inventor of England’s first jet engine.
Like the jet engine that powered it, the plane had a number of
predecessors. In fact, the May, 1941, flight was not the first jetpowered
test flight: That flight occurred on August 27, 1939, when a
Heinkel aircraft powered by a jet engine developed by Hans Pabst
von Ohain completed a successful test flight in Germany. During
this period, Italian airplane builders were also engaged in jet aircraft
testing, with lesser degrees of success.
Without the knowledge that had been gained from Whittle’s experience
in experimental aviation, the test flight at the Royal Air
Force’s Cranwell airfield might never have been possible. Whittle’s
repeated efforts to develop turbojet propulsion engines had begun
in 1928, when, as a twenty-one-year-old Royal Air Force (RAF)
flight cadet at Cranwell Academy, he wrote a thesis entitled “Future
Developments in Aircraft Design.” One of the principles of Whittle’s
earliest research was that if aircraft were eventually to achieve
very high speeds over long distances, they would have to fly at very

808 / Turbojet
high altitudes, benefiting from the reduced wind resistance encountered
at such heights.
Whittle later stated that the speed he had in mind at that time
was about 805 kilometers per hour—close to that of the first jetpowered
aircraft. His earliest idea of the engines that would be necessary
for such planes focused on rocket propulsion (that is, “jets” in
which the fuel and oxygen required to produce the explosion needed
to propel an air vehicle are entirely contained in the engine, or, alternatively,
in gas turbines driving propellers at very high speeds).
Later, it occurred to him that gas turbines could be used to provide
forward thrust by what would become “ordinary” jet propulsion
(that is, “thermal air” engines that take from the surrounding atmosphere
the oxygen they need to ignite their fuel). Eventually, such
ordinary jet engines would function according to one of four possible
systems: the so-called athodyd, or continuous-firing duct; the
pulsejet, or intermittent-firing duct; the turbojet, or gas-turbine jet;
or the propjet, which uses a gas turbine jet to rotate a conventional
propeller at very high speeds.
Passing the Test
The aircraft that was to be used to test the flight performance
was completed by April, 1941. On April 7, tests were conducted
on the ground at Gloster Aircraft’s landing strip at Brockworth
by chief test pilot Sayer. At this point, all parties concerned tried
to determine whether the jet engine’s capacity would be sufficient
to push the aircraft forward with enough speed to make it
airborne. Sayer dared to take the plane off the ground for a limited
distance of between 183 meters and 273 meters, despite the
technical staff’s warnings against trying to fly in the first test
flights.
On May 15, the first real test was conducted at Cranwell. During
that test, Sayer flew the plane, now called the Pioneer, for seventeen
minutes at altitudes exceeding 300 meters and at a conservative test
speed exceeding 595 kilometers per hour, which was equivalent to
the top speed then possible in the RAF’s most versatile fighter
plane, the Spitfire.

Once it was clear that the tests undertaken at Cranwell were not
only successful but also highly promising in terms of even better
performance, a second, more extensive test was set for May 21, 1941.
It was this later demonstration that caused the Ministry of Air Production
(MAP) to initiate the first steps to produce the Meteor jet
fighter aircraft on a full industrial scale barely more than a year after
the Cranwell test flight.
Impact
Turbojet / 809
Since July, 1936, the Junkers engine and aircraft companies in
Hitler’s Germany had been a part of a new secret branch dedicated
to the development of a turbojet-driven aircraft. In the same period,
Junkers’ rival in the German aircraft industry, Heinkel, Inc., approached
von Ohain, who was far enough along in his work on the
turbojet principle to have patented a device very similar to Whittle’s
in 1935. Alater model of this jet engine would power a test aircraft in
August, 1939.
In the meantime, the wider impact of the flight was the result of
decisions made by General Henry Harley Arnold, chief of staff of
the U.S. Army Air Corps. Even before learning of the successful
flight in May, he made arrangements to have one of Whittle’s engines
shipped to the United States to be used by General Electric
Company as a model for U.S. production. The engine arrived in
October, 1941, and within one year, a General Electric-built engine
powered a Bell Aircraft plane, the XP-59 A Airacomet, in its
maiden flight.
The jet airplane was not perfected in time to have any significant
impact on the outcome of World War II, but all of the wartime experimental
jet aircraft developments that were either sparked by the
flight in 1941 or preceded it prepared the way for the research and
development projects that would leave a permanent revolutionary
mark on aviation history in the early 1950’s.
See also Airplane; Dirigible; Rocket; Rocket; Stealth aircraft; Supersonic
passenger plane; V-2 rocket.

810 / Turbojet
Further Reading
Adams, Robert. “Smithsonian Horizons.” Smithsonian 18 (July, 1987).
Boyne, Walter J., Donald S. Lopez, and Anselm Franz. The Jet Age:
Forty Years of Jet Aviation. Washington: National Air and Space
Museum, 1979.
Constant, Edward W. The Origins of the Turbojet Revolution. Baltimore:
Johns Hopkins University Press, 1980.
Launius, Roger D. Innovation and the Development of Flight. College
Station: Texas A&M University Press, 1999.

Typhus vaccine
Typhus vaccine
The invention: the first effective vaccine against the virulent typhus
disease.
The person behind the invention:
Hans Zinsser (1878-1940), an American bacteriologist and
immunologist
Studying Diseases
811
As a bacteriologist and immunologist, Hans Zinsser was interested
in how infectious diseases spread. During an outbreak of typhus
in Serbia in 1915, he traveled with a Red Cross team so that he
could study the disease. He made similar trips to the Soviet Union
in 1923, Mexico in 1931, and China in 1938. His research showed
that, as had been suspected, typhus was caused by the rickettsia, an
organism that had been identified in 1916 by Henrique da Rocha-
Lima. The organism was known to be carried by a louse or a rat flea
and transmitted to humans through a bite. Poverty, dirt, and overcrowding
led to environments that helped the typhus disease to
spread.
The rickettsia is a microorganism that is rod-shaped or spherical.
Within the insect’s body, it works its way into the cells that line the
gut. Multiplying within this tissue, the rickettsia passes from the insect
body with the feces. Since its internal cells are being destroyed,
the insect dies within three weeks after it has been infected with the
microorganism. As the infected flea or louse feeds on a human, it
causes itching. When the bite is scratched, the skin may be opened,
and the insect feces, carrying rickettsia, can then enter the body.
Also, dried airborne feces can be inhaled.
Once inside the human, the rickettsia invades endothelial cells
and causes an inflammation of the blood vessels. Cell death results,
and this leads to tissue death. In a few days, the infected person may
have a rash, a severe headache, a fever, dizziness, ringing in the ears,
or deafness. Also, light may hurt the person’s eyes, and the thinking
processes become foggy and mixed up. (The word “typhus” comes

812 / Typhus vaccine
from a Greek word meaning “cloudy” or “misty.”) Without treatment,
the victim dies within nine to eighteen days.
Medical science now recognizes three forms of typhus: the epidemic
louse-borne, the Brill-Zinsser, and the murine (or rodentrelated)
form. The epidemic louse-borne (or “classical”) form is the
most severe. The Brill-Zinsser (or “endemic”) form is similar but
less severe. The murine form of typhus is also milder then the epidemic
type.
In 1898, a researcher named Brill studied typhus among immigrants
in New York City; the form of typhus he found was called
“Brill’s disease.” In the late 1920’s, Hermann Mooser proved that
Brill’s disease was carried by the rat flea.
When Zinsser began his work on typhus, he realized that what
was known about the disease had never been properly organized.
Zinsser and his coworkers, including Mooser and others, worked to
identify the various types of typhus. In the 1930’s, Zinsser suggested
that the typhus studied by Brill in New York City had actually
included two types: the rodent-associated form and Brill’s disease.
As a result of Zinsser’s effort to identify the types of typhus
disease, it was renamed Brill-Zinsser disease.
Making a Vaccine
Zinsser’s studies had shown him that the disease-causing organism
in typhus contained some kind of antigen, most likely a polysaccharide.
In 1932, Zinsser would identify agglutinins, or antibodies,
in the blood serum of patients who had the murine and classical
forms of typhus. Zinsser believed that a vaccine could be developed
to prevent the spread of typhus. He realized, however, that a large
number of dead microorganisms was needed to help people develop
an immunity.
Zinsser and his colleagues set out to develop a method of growing
organisms in large quantities in tissue culture. The infected tissue
was used to inoculate large quantities of normal chick tissue,
and this tissue was then grown in flasks. In this way, Zinsser’s team
was able to produce the quantities of microorganisms they needed.
The type of immunization that Zinsser developed (in 1930) is
known as “passive immunity.” The infecting organisms carry anti-

gens, which stimulate the production of antibodies. The antigens
can elicit an immune reaction even if the cell is weak or dead.
“B” cells and macrophages, both of which are used in fighting
disease organisms, recognize and respond to the antigen. The B cells
produce antibodies that can destroy the invading organism directly
or attract more macrophages to the area so that they can attack the
organism. B cells also produce “memory cells,” which remain in the
blood and trigger a quick second response if there is a later infection.
Since the vaccine contains weakened or dead organisms, the
person who is vaccinated may have a mild reaction but does not actually
come down with the disease.
Impact
Typhus vaccine / 813
Typhus is still common in many parts of the world, especially
where there is poverty and overcrowding. Classical typhus is quite
rare; the last report of this type of typhus in the United States was in
1921. Endemic and murine typhus are more common. In the United
States, where children are vaccinated against the disease, only about
fifty cases are now reported each year. Antibiotics such as tetracycline
and chloramphenicol are effective in treating the disease, so
few infected people now die of the disease in areas where medical
care is available.
The work of Zinsser and his colleagues was very important in
stopping the spread of typhus. Zinsser’s classification of different
types of the disease meant that it was better understood, and this
led to the development of cures. The control of lice and rodents and
improved cleanliness in living conditions helped bring typhus under
control. Once Zinsser’s vaccine was available, even people who
lived in crowded inner cities could be protected against the disease.
Zinsser’s research in growing the rickettsia in tissue culture also
inspired further work. Other researchers modified and improved
his technique so that the use of tissue culture is now standard in laboratories.
See also Antibacterial drugs; Birth control pill; Penicillin; Polio
vaccine (Sabin); Polio vaccine (Salk); Salvarsan; Tuberculosis vaccine;
Yellow fever vaccine.

814 / Typhus vaccine
Further Reading
DeJauregui, Ruth. 100 Medical Milestones That Shaped World History.
San Mateo, Calif.: Bluewood Books, 1998.
Gray, Michael W. “Rickettsia in Medicine and History.” Nature 396,
no. 6707 (November, 1998).
Hoff, Brent H., Carter Smith, and Charles H. Calisher. Mapping Epidemics:
A Historical Atlas of Disease. New York: Franklin Watts,
2000.

Ultracentrifuge
Ultracentrifuge
The invention: A super-high-velocity centrifuge designed to separate
colloidal or submicroscopic substances, the ultracentrifuge
was used to measure the molecular weight of proteins and
proved that proteins are large molecules.
The people behind the invention:
Theodor Svedberg (1884-1971), a Swedish physical chemist and
1926 Nobel laureate in chemistry
Jesse W. Beams (1898-1977), an American physicist
Arne Tiselius (1902-1971), a Swedish physical biochemist and
1948 Nobel laureate in chemistry
Svedberg Studies Colloids
815
Theodor “The” Svedberg became the principal founder of molecular
biology when he invented the ultracentrifuge and used it to
examine proteins in the mid-1920’s. He began to study materials
called “colloids” as a Swedish chemistry student at the University
of Uppsala and continued to conduct experiments with colloidal
systems when he joined the faculty in 1907. A colloid is a kind of
mixture in which very tiny particles of one substance are mixed
uniformly with a dispersing medium (often water) and remain
suspended indefinitely. These colloidal dispersions play an important
role in many chemical and biological systems.
The size of the colloid particles must fall within a certain
range. The force of gravity will cause them to settle if they are too
large. If they are too small, the properties of the mixture change,
and a solution is formed. Some examples of colloidal systems include
mayonnaise, soap foam, marshmallows, the mineral opal,
fog, India ink, jelly, whipped cream, butter, paint, and milk.
Svedberg wondered what such different materials could have in
common. His early work helped to explain why colloids remain
in suspension. Later, he developed the ultracentrifuge to measure
the weight of colloid particles by causing them to settle in a controlled
way.

816 / Ultracentrifuge
Svedberg Builds an Ultracentrifuge
Svedberg was a successful chemistry professor at the University
of Uppsala in Sweden when he had the idea that colloids could be
made to separate from suspension by means of centrifugal force.
Centrifugal force is caused by circular motion and acts on matter
much as gravity does. A person can feel this force by tying a ball to a
rope and whirling it rapidly in a circle. The pull on the rope becomes
stronger as the ball moves faster in its circular orbit. A centrifuge
works the same way: It is a device that spins balanced containers of
substances very rapidly.
Svedberg figured that it would take a centrifugal force thousands
of times the force of gravity to cause colloid particles to settle. How
fast they settle depends on their size and weight, so the ultracentrifuge
can also provide a measure of these properties. Centrifuges were
already used to separate cream from whole milk and blood corpuscles
from plasma, but these centrifuges were too slow to cause the
separation of colloids. An ultracentrifuge—one that could spin samples
much faster—was needed, and Svedberg made plans to build one.
The opportunity came in 1923, when Svedberg spent eight months
as visiting professor in the chemistry department of the University
of Wisconsin at Madison and worked with J. Burton Nichols, one of
the six graduate students assigned to assist him. Here, Svedberg announced
encouraging results with an electrically driven centrifuge—not
yet an ultracentrifuge—which attained a rotation equal
to about 150 times the force of gravity. Svedberg returned to Sweden
and, within a year, built a centrifuge capable of generating 7,000
times the force of gravity. He used it with Herman Rinde, a colleague
at the University of Uppsala, to separate the suspended particles
of colloidal gold. This was in 1924, which is generally accepted
as the date of the first use of a true ultracentrifuge. From 1925 to
1926, Svedberg raised the funds to build an even more powerful ultracentrifuge.
It would be driven by an oil turbine, a machine capable
of producing more than 40,000 revolutions per minute to generate
a force 100,000 times that of gravity.
Svedberg and Robin Fahraeus used the new ultracentrifuge to
separate the protein hemoglobin from its colloidal suspension. Together
with fats and carbohydrates, proteins are one of the most

abundant organic constituents of living organisms. No protein had
been isolated in pure form before Svedberg began this study, and it
was uncertain whether proteins consisted of molecules of a single
compound or mixtures of different substances working together in
biological systems. The colloid particles of Svedberg’s previous
studies separated at different rates, some settling faster than others,
showing that they had different sizes and weights. Colloid particles
of the protein, however, separated together. The uniform separation
observed for proteins, such as hemoglobin, demonstrated for the
first time that each protein consists of identical well-defined molecules.
More than one hundred proteins were studied by Svedberg
and his coworkers, who extended their technique to carbohydrate
polymers such as cellulose and starch.
Impact
Svedberg built more and more powerful centrifuges so that smaller
and smaller molecules could be studied. In 1936, he built an ultracentrifuge
that produced a centrifugal force of more than a halfmillion
times the force of gravity. Jesse W. Beams was an American
pioneer in ultracentrifuge design. He reduced the friction of an airdriven
rotor by first housing it in a vacuum, in 1934, and later by
supporting it with a magnetic field.
The ultracentrifuge was a central tool for providing a modern understanding
of the molecular basis of living systems, and it is employed
in thousands of laboratories for a variety of purposes. It is
used to analyze the purity and the molecular properties of substances
containing large molecules, from the natural products of the biosciences
to the synthetic polymers of chemistry. The ultracentrifuge is
also employed in medicine to analyze body fluids, and it is used in biology
to isolate viruses and the components of fractured cells.
Svedberg, while at Wisconsin in 1923, invented a second, very
different method to separate proteins in suspension using electric
currents. It is called “electrophoresis,” and it was later improved by
his student, Arne Tiselius, for use in his famous study of the proteins
in blood serum. The technique of electrophoresis is as widespread
and important as is the ultracentrifuge.
See also Ultramicroscope; X-ray crystallography.
Ultracentrifuge / 817

818 / Ultracentrifuge
Further Reading
Lechner, M. D. Ultracentrifugation. New York: Springer, 1994.
Rickwood, David. Preparative Centrifugation: A Practical Approach.
New York: IRL Press at Oxford University Press, 1992.
Schuster, Todd M. Modern Analytical Ultracentrifugation: Acquisition
and Interpretation of Data for Biological and Synthetic Polymer Systems.
Boston: Birkhäuser, 1994.
Svedberg, Theodor B., Kai Oluf Pedersen, and Johannes Henrik
Bauer. The Ultracentrifuge. Oxford: Clarendon Press, 1940.

Ultramicroscope
Ultramicroscope
The invention: A microscope characterized by high-intensity illumination
for the study of exceptionally small objects, such as colloidal
substances.
The people behind the invention:
Richard Zsigmondy (1865-1929), an Austrian-born German
organic chemist who won the 1925 Nobel Prize in Chemistry
H. F. W. Siedentopf (1872-1940), a German physicist-optician
Max von Smouluchowski (1879-1961), a German organic
chemist
Accidents of Alchemy
819
Richard Zsigmondy’s invention of the ultramicroscope grew out
of his interest in colloidal substances. Colloids consist of tiny particles
of a substance that are dispersed throughout a solution of another
material or substance (for example, salt in water). Zsigmondy
first became interested in colloids while working as an assistant to
the physicist Adolf Kundt at the University of Berlin in 1892. Although
originally trained as an organic chemist, in which discipline
he took his Ph.D. at the University of Munich in 1890, Zsigmondy
became particularly interested in colloidal substances containing
fine particles of gold that produce lustrous colors when painted on
porcelain. For this reason, he abandoned organic chemistry and devoted
his career to the study of colloids.
Zsigmondy began intensive research into his new field of interest
in 1893, when he returned to Austria to accept a post as lecturer at a
technical school at Graz. Zsigmondy became especially interested
in gold-ruby glass, the accidental invention of the seventeenth century
alchemist Johann Kunckle. Kunckle, while pursuing the alchemist’s
pipe dream of transmuting base substances (such as lead)
into gold, discovered instead a method of producing glass with a
beautiful, deep red luster by suspending very fine particles of gold
throughout the liquid glass before it was cooled. Zsigmondy also
began studying a colloidal pigment called “purple of Cassius,” the
discovery of another seventeenth century alchemist, Andreas Cassius.

820 / Ultramicroscope
Zsigmondy soon discovered that purple of Cassius was a colloidal
solution and not, as most chemists believed at the time, a chemical
compound. This fact allowed him to develop techniques for
glass and porcelain coloring with great commercial value, which led
directly to his 1897 appointment to a research post with the Schott
Glass Manufacturing Company in Jena, Germany. With the Schott
Company, Zsigmondy concentrated on the commercial production
of colored glass objects. His most notable achievement during this
period was the invention of Jena milk glass, which is still prized by
collectors throughout the world.
Brilliant Proof
While studying colloids, Zsigmondy devised experiments that
proved that purple of Cassius was colloidal. When he published the
results of his research in professional journals, however, they were
not widely accepted by the scientific community. Other scientists
were not able to replicate Zsigmondy’s experiments and consequently
denounced them as flawed. The criticism of his work in
technical literature stimulated Zsigmondy to make his greatest discovery,
the ultramicroscope, which he developed to prove his theories
regarding purple of Cassius.
The problem with proving the exact nature of purple of Cassius
was that the scientific instruments available at the time were not
sensitive enough for direct observation of the particles suspended
in a colloidal substance. Using the facilities and assisted by the staff
(especially H. F. W. Siedentopf, an expert in optical lens grinding) of
the Zeiss Glass Manufacturing Company of Jena, Zsigmondy developed
an ingenious device that permitted direct observation of individual
colloidal particles.
This device, which its developers named the “ultramicroscope,”
made use of a principle that already existed. Sometimes called “darkfield
illumination,” this method consisted of shining a light (usually
sunlight focused by mirrors) through the solution under the microscope
at right angles to the observer, rather than shining the light directly
from the observer into the solution. The resulting effect is similar
to that obtained when a beam of sunlight is admitted to a closed
room through a small window. If an observer stands back from and at

ight angles to such a beam, many dust particles suspended in the air
will be observed that otherwise would not be visible.
Zsigmondy’s device shines a very bright light through the substance
or solution being studied. From the side, the microscope then
focuses on the light shaft. This process enables the observer using
the ultramicroscope to view colloidal particles that are ordinarily
invisible even to the strongest conventional microscope. To a scientist
viewing purple of Cassius, for example, colloidal gold particles
as small as one ten-millionth of a millimeter in size become visible.
Impact
Richard Zsigmondy
Ultramicroscope / 821
Born in Vienna, Austria, in 1865, Richard Adolf Zsigmondy
came from a talented, energetic family. His father, a celebrated
dentist and inventor of medical equipment, inspired his children
to study the sciences, while his mother urged them to
spend time outdoors in strenuous exercise. Although his father
died when Zsigmondy was fifteen, the teenager’s interest in
chemistry was already firmly established. He read advanced
chemistry textbooks and worked on experiments in his own
home laboratory.
After taking his doctorate at the University of Munich and
teaching in Berlin and Graz, Austria, he became an industrial
chemist at the glassworks in Jena, Germany. However, pure research
was his love, and he returned to it, working entirely on
his own after 1900. In 1907 he received an appointment as professor
and director of the Institute of Inorganic Chemistry at the
University of Göttingen, one of the scientific centers of the
world. There he accomplished much of his ground-breaking
work on colloids and Brownian motion, despite the severe
shortages that hampered him during the economic depression
in Germany following World War I. His 1925 Nobel Prize in
Chemistry, especially the substantial money award, helped him
overcome his supply problems. He retired in early 1929 and
died seven months later.
After Zsigmondy’s invention of the ultramicroscope in 1902,
the University of Göttingen appointed him professor of inorganic

822 / Ultramicroscope
chemistry and director of its Institute for Inorganic Chemistry.
Using the ultramicroscope, Zsigmondy and his associates quickly
proved that purple of Cassius is indeed a colloidal substance.
That finding, however, was the least of the spectacular discoveries
that resulted from Zsigmondy’s invention. In the next decade,
Zsigmondy and his associates found that color changes in colloidal
gold solutions result from coagulation—that is, from changes in the
size and number of gold particles in the solution caused by particles
bonding together. Zsigmondy found that coagulation occurs when
the negative electrical charge of the individual particles is removed
by the addition of salts. Coagulation can be prevented or slowed by
the addition of protective colloids.
These observations also made possible the determination of the
speed at which coagulation takes place, as well as the number of particles
in the colloidal substance being studied. With the assistance of
the organic chemist Max von Smouluchowski, Zsigmondy worked
out a complete mathematical formula of colloidal coagulation that is
valid not only for gold colloidal solutions but also for all other
colloids. Colloidal substances include blood and milk, which both coagulate,
thus giving Zsigmondy’s work relevance to the fields of
medicine and agriculture. These observations and discoveries concerning
colloids—in addition to the invention of the ultramicroscope—earned
for Zsigmondy the 1925 Nobel Prize in Chemistry.
See also Scanning tunneling microscope; Ultracentrifuge; X-ray
crystallography.
Further Reading
Zsigmondy, Richard, and Jerome Alexander. Colloids and the Ultramicroscope.
New York: J. Wiley & Sons, 1909.
Zsigmondy, Richard, Ellwood Barker Spear, and John Foote Norton.
The Chemistry of Colloids. New York: John Wiley & Sons, 1917.

Ultrasound
Ultrasound
The invention: A medically safe alternative to X-ray examination,
ultrasound uses sound waves to detect fetal problems in pregnant
women.
The people behind the invention:
Ian T. Donald (1910-1987), a British obstetrician
Paul Langévin (1872-1946), a French physicist
Marie Curie (1867-1946) and Pierre Curie (1859-1906), the
French husband-and-wife team that researched and
developed the field of radioactivity
Alice Stewart, a British researcher
An Underwater Beginning
823
In the early 1900’s, two major events made it essential to develop
an appropriate means for detecting unseen underwater objects. The
first event was the Titanic disaster in 1912, which involved a largely
submerged, unseen, and silent iceberg. This iceberg caused the sinking
of the Titanic and resulted in the loss of many lives as well as
valuable treasure. The second event was the threat to the Allied
Powers from German U-boats during World War I (1914-1918). This
threat persuaded the French and English Admiralties to form a joint
committee in 1917. The Anti-Submarine Detection and Investigation
Committee (ASDIC) found ways to counter the German naval
developments. Paul Langévin, a former colleague of Pierre Curie
and Marie Curie, applied techniques developed in the Curies’ laboratories
in 1880 to formulate a crude ultrasonic system to detect submarines.
These techniques used beams of sound waves of very high
frequency that were highly focused and directional.
The advent of World War II (1939-1945) made necessary the development
of faster electronic detection technology to improve the efforts
of ultrasound researchers. Langévin’s crude invention evolved
into the sophisticated system called “sonar” (sound navigation ranging),
which was important in the success of the Allied forces. Sonar
was based on pulse echo principles and, like the system called “ra-

824 / Ultrasound
dar” (radio detecting and ranging), had military implications. This vital
technology was classified as a military secret and was kept hidden
until after the war.
An Alternative to X Rays
Ian Donald
Ian Donald was born in Paisley, Scotland, in 1910 and educated
in Edinburgh until he was twenty, when he moved to
South Africa with his parents. He graduated with a bachelor of
arts degree from Diocesan College, Cape Town, and then moved
to London to study medicine, graduating from the University of
London in 1937. During World War II he served as a medical officer
in the Royal Air Force and received a medal for rescuing flyers
from a burning airplane. After the war he began his long
teaching career in medicine, first at St. Thomas Hospital Medical
School and then as the Regius Professor of Midwifery at Glasgow
University. His specialties were obstetrics and gynecology.
While at Glasgow he accomplished his pioneering work
with diagnostic ultrasound technology, but he also championed
laparoscopy, breast feeding, and the preservation of membranes
during the delivery of babies. In addition to his teaching
duties and medical practice he wrote a widely used textbook,
oversaw the building of the Queen Mother’s Hospital in Glasgow,
and campaigned against England’s 1967 Abortion Act.
His expertise with ultrasound came to his own rescue after
he had cardiac surgery in the 1960’s. He diagnosed himself as
having internal bleeding from a broken blood vessel. The cardiologists
taking care of him were skeptical until an ultrasound
proved him right. Widely honored among physicians, he died
in England in 1987.
Ian Donald’s interest in engineering and the principles of
sound waves began when he was a schoolboy. Later, while he was
in the British Royal Air Force, he continued and maintained his
enthusiasm by observing the development of the anti-U-boat
warfare efforts. He went to medical school after World War II and
began a career in obstetrics. By the early 1950’s, Donald had em-

Ultrasound / 825
Safe and not requiring surgery, ultrasonography has become the principal means for obtaining
information about fetal structures. (Digital Stock)
barked on a study of how to apply sonar technology in medicine.
He moved to Glasgow, Scotland, a major engineering center in
Europe that presented a fertile environment for interdisciplinary
research. There Donald collaborated with engineers and technicians
in his medical ultrasound research. They used inanimate
and tissue materials in many trials. Donald hoped to apply ultrasound
technology to medicine, especially to gynecology and obstetrics,
his specialty.
His efforts led to new pathways and new discoveries. He was interested
in adapting a certain type of ultrasound technology method
(used to probe metal structures and welds for cracks and flaws) to
medicine. Kelvin Hughes, the engineering manufacturing company
that produced the flaw detector apparatus, gave advice, expertise,
and equipment to Donald and his associates, who were then able to
devise water tanks with flexible latex bottoms. These were coated
with a film of grease and placed into contact with the abdomens of
pregnant women.
The use of diagnostic radiography (such as X rays) became controversial
when it was evident that it caused potential leukemias

826 / Ultrasound
and other injuries to the fetus. It was realized from the earliest days
of radiology that radiation could cause tumors, particularly of the
skin. The aftereffects of radiological studies were recognized much
later and confirmed by studies of atomic bomb survivors and of patients
receiving therapeutic irradiation. The use of radiation in obstetrics
posed several major threats to the developing fetus, most
notably the production of tumors later in life, genetic damage, and
developmental anomalies in the unborn fetus.
In 1958, bolstered by earlier clinical reports and animal research
findings, Alice Stewart and her colleagues presented a major case
study of more than thirteen hundred children in England and Wales
who had died of cancer before the age of ten between 1953 and 1958.
There was a 91 percent increase in leukemias in children who were
exposed to intrauterine radiation, as well as a higher percentage of
fetal death. Although controversial, this report led to a reduction in
the exposure of pregnant women to X rays, with subsequent reductions
in fetal abnormalities and death.
These reports came at a very opportune time for Donald: The development
of ultrasonography would provide useful information
about the unborn fetus without the adverse effects of radiation.
Stewart’s findings and Donald’s experiments convinced others of
the need for ultrasonography in obstetrics.
Consequences
Diagnostic ultrasound first gained clinical acceptance in obstetrics,
and its major contributions have been in the assessment of fetal
size and growth. In combination with amniocentesis (the study of
fluid taken from the womb), ultrasound is an invaluable tool in operative
procedures necessary to improve the outcomes of pregnancies.
As can be expected, safety has been a concern, especially for a developing,
vulnerable fetus that is exposed to high-frequency sound.
Research has not been able to document any harmful effect of ultrasonography
on the developing fetus. The procedure produces neither
heat nor cold. It has not been shown to produce any toxic or destructive
effect on the auditory or balancing organs of the
developing fetus. Chromosomal abnormalities have not been reported
in any of the studies conducted.

Ultrasonography, because it is safe and does not require surgery,
has become the principal means for obtaining information about fetal
structures. With this procedure, the contents of the uterus—as
well as the internal structure of the placenta, fetus, and fetal organs—can
be evaluated at any time during pregnancy. The use of
ultrasonography remains a most valued tool in medicine, especially
obstetrics, because of Donald’s work.
See also Amniocentesis; Birth control pill; CAT scanner; Electrocardiogram;
Electroencephalogram; Mammography; Nuclear magnetic
resonance; Pap test; Sonar; Syphilis test; X-ray image intensifier.
Further Reading
Ultrasound / 827
Danforth, David N., and James R. Scott. Danforth’s Obstetrics and Gynecology.
7th ed. Philadelphia: Lippincott, 1994.
DeJauregui, Ruth. 100 Medical Milestones That Shaped World History.
San Mateo, Calif.: Bluewood Books, 1998.
Rozycki, Grace S. Surgeon-Performed Ultrasound: Its Use in Clinical
Practice. Philadelphia: W. B. Saunders, 1998.
Wolbarst, Anthony B. Looking Within: How X-ray, CT, MRI, Ultrasound,
and Other Medical Images Are Created, and How They Help
Physicians Save Lives. Berkeley: University of California Press,
1999.

828
UNIVAC computer
UNIVAC computer
The invention: The first commercially successful computer system.
The people behind the invention:
John Presper Eckert (1919-1995), an American electrical engineer
John W. Mauchly (1907-1980), an American physicist
John von Neumann (1903-1957), a Hungarian American
mathematician
Howard Aiken (1900-1973), an American physicist
George Stibitz (1904-1995), a scientist at Bell Labs
The Origins of Computing
On March 31, 1951, the U.S. Census Bureau accepted delivery of
the first Universal Automatic Computer (UNIVAC). This powerful
electronic computer, far surpassing anything then available in technological
features and capability, ushered in the first computer generation
and pioneered the commercialization of what had previously
been the domain of academia and the interest of the military. The fanfare
that surrounded this historic occasion, however, masked the turbulence
of the previous five years for the young upstart Eckert-
Mauchly Computer Corporation (EMCC), which by this time was a
wholly owned subsidiary of Remington Rand Corporation.
John Presper Eckert and John W. Mauchly met in the summer of
1941 at the University of Pennsylvania. A short time later, Mauchly,
then a physics professor at Ursinus College, joined the Moore School
of Engineering at the University of Pennsylvania and embarked on a
crusade to convince others of the feasibility of creating electronic digital
computers. Up to this time, the only computers available were
called “differential analyzers,” which were used to solve complex
mathematical equations known as “differential equations.” These
slow machines were good only for solving a relatively narrow range
of mathematical problems.
Eckert and Mauchly landed a contract that eventually resulted in
the development and construction of the world’s first operational

general-purpose electronic computer, the Electronic Numerical Integrator
and Calculator (ENIAC). This computer, used eventually
by the Army for the calculation of ballistics tables, was deficient in
many obvious areas, but this was caused by economic rather than
engineering constraints. One major deficiency was the lack of automatic
program control; the ENIAC did not have stored program
memory. This was addressed in the development of the Electronic
Discrete Variable Automatic Computer (EDVAC), the successor to
the ENIAC.
Fighting the Establishment
UNIVAC computer / 829
A symbiotic relationship had developed between Eckert and
Mauchly that worked to their advantage on technical matters.
They worked well with each other, and this contributed to their
success in spite of external obstacles. They both were interested in
the commercial applications of computers and envisioned uses for
these machines far beyond the narrow applications required by
the military.
This interest brought them into conflict with the administration
at the Moore School of Engineering as well as with the noted mathematician
John von Neumann, who “joined” the ENIAC/EDVAC
development team in 1945. Von Neumann made significant contributions
and added credibility to the Moore School group, which often
had to fight against the conservative scientific establishment
characterized by Howard Aiken at Harvard University and George
Stibitz at Bell Labs. Philosophical differences between von Neumann
and Eckert and Mauchly, as well as patent issue disputes with
the Moore School administration, eventually caused the resignation
of Eckert and Mauchly on March 31, 1946.
Eckert and Mauchly, along with some of their engineering colleagues
at the University of Pennsylvania, formed the Electronic
Control Company and proceeded to interest potential customers
(including the Census Bureau) in an “EDVAC-type” machine. On
May 24, 1947, the EDVAC-type machine became the UNIVAC. This
new computer would overcome the shortcomings of the ENIAC
and the EDVAC (which was eventually completed by the Moore
School in 1951). It would be a stored-program computer and would

830 / UNIVAC computer
allow input to and output from the computer via magnetic tape. The
prior method of input/output used punched paper cards that were
extremely slow compared to the speed at which data in the computer
could be processed.
A series of poor business decisions and other unfortunate circumstances
forced the newly renamed Eckert-Mauchly Computer
Corporation to look for a buyer. They found one in Remington Rand
in 1950. Remington Rand built tabulating equipment and was a
competitor of International Business Machines Corporation (IBM).
IBM was approached about buying EMCC, but the negotiations fell
apart. EMCC became a division of Remington Rand and had access
to the resources necessary to finish the UNIVAC.
Consequences
Eckert and Mauchly made a significant contribution to the advent
of the computer age with the introduction of the UNIVAC I.
The words “computer” and “UNIVAC” entered the popular vocabulary
as synonyms. The efforts of these two visionaries were rewarded
quickly as contracts started to pour in, taking IBM by surprise
and propelling the inventors into the national spotlight.
This spotlight shone brightest, perhaps, on the eve of the national
presidential election of 1952, which pitted war hero General Dwight
D. Eisenhower against statesman Adlai Stevenson. At the suggestion
of Remington Rand, CBS was invited to use UNIVAC to predict
the outcome of the election. Millions of television viewers watched
as CBS anchorman Walter Cronkite “asked” UNIVAC for its predictions.
A program had been written to analyze the results of thousands
of voting districts in the elections of 1944 and 1948. Based on
only 7 percent of the votes coming in, UNIVAC had Eisenhower
winning by a landslide, in contrast with all the prior human forecasts
of a close election. Surprised by this answer and not willing to
suffer the embarrassment of being wrong, the programmers quickly
directed the program to provide an answer that was closer to the
perceived situation. The outcome of the election, however, matched
UNIVAC’s original answer. This prompted CBS commentator Edward
R. Murrow’s famous quote, “The trouble with machines is
people.”

The development of the UNIVAC I produced many technical innovations.
Primary among these is the use of magnetic tape for input
and output. All machines that preceded the UNIVAC (with one
exception) used either paper tape or cards for input and cards for
output. These methods were very slow and created a bottleneck of
information. The great advantage of magnetic tape was the ability
to store the equivalent of thousands of cards of data on one 30-centimeter
reel of tape. Another advantage was its speed.
See also Apple II computer; BINAC computer; Colossus computer;
ENIAC computer; IBM Model 1401 computer; Personal computer;
Supercomputer.
Further Reading
UNIVAC computer / 831
Metropolis, Nicholas, Jack Howlett, and Gian Carlo Rota. A History
of Computing in the Twentieth Century: A Collection of Essays. New
York: Academic Press, 1980.
Slater, Robert. Portraits in Silicon. Cambridge, Mass.: MIT Press,
1987.
Stern, Nancy B. From ENIAC to UNIVAC: An Appraisal of the Eckert-
Mauchly Computers. Bedford, Mass.: Digital Press, 1981.

832
Vacuum cleaner
Vacuum cleaner
The invention: The first portable domestic vacuum cleaner successfully
adapted to electricity, the original machine helped begin
the electrification of domestic appliances in the early twentieth
century.
The people behind the invention:
H. Cecil Booth (1871-1955), a British civil engineer
Melville R. Bissell (1843-1889), the inventor and marketer of the
Bissell carpet sweeper in 1876
William Henry Hoover (1849-1932), an American industrialist
James Murray Spangler (1848-1915), an American inventor
From Brooms to Bissells
During most of the nineteenth century, the floors of homes
were cleaned primarily with brooms. Carpets were periodically
dragged out of the home by the boys and men of the family,
stretched over rope lines or fences, and given a thorough beating
to remove dust and dirt. In the second half of the century, carpet
sweepers, perhaps inspired by the success of street-sweeping machines,
began to appear. Although there were many models, nearly
all were based upon the idea of a revolving brush within an outer
casing that moved on rollers or wheels when pushed by a long
handle.
Melville Bissell’s sweeper, patented in 1876, featured a knob for
adjusting the brushes to the surface. The Bissell Carpet Company,
also formed in 1876, became the most successful maker of carpet
sweepers and dominated the market well into the twentieth century.
Electric vacuum cleaners were not feasible until homes were
wired for electricity and the small electric motor was invented.
Thomas Edison’s success with an incandescent lighting system in
the 1880’s and Nikola Tesla’s invention of a small electric motor
that was used in 1889 to drive a Westinghouse Electric Corporation
fan opened the way for the application of electricity to household
technologies.

Cleaning with Electricity
Vacuum cleaner / 833
In 1901, H. Cecil Booth, a British civil engineer, observed a London
demonstration of an American carpet cleaner that blew compressed
air at the fabric. Booth was convinced that the process
should be reversed so that dirt would be sucked out of the carpet. In
developing this idea, Booth invented the first successful suction
vacuum sweeper.
Booth’s machines, which were powered by gasoline or electricity,
worked without brushes. Dust was extracted by means of a
suction action through flexible tubes with slot-shaped nozzles.
Some machines were permanently installed in buildings that had
wall sockets for the tubes in every room. Booth’s British Vacuum
Cleaner Company also employed horse-drawn mobile units from
which white-uniformed men unrolled long tubes that they passed
into buildings through windows and doors. His company’s commercial
triumph came when it cleaned Westminster Abbey for the
coronation of Edward VII in 1902. Booth’s company also manufactured
a 1904 domestic model that had a direct-current electric motor
and a vacuum pump mounted on a wheeled carriage. Dust was
sucked into the nozzle of a long tube and deposited into a metal
container. Booth’s vacuum cleaner used electricity from overhead
light sockets.
The portable electric vacuum cleaner was invented in 1907 in the
United States by James Murray Spangler. When Spangler was a janitor
in a department store in Canton, Ohio, his asthmatic condition
was worsened by the dust he raised with a large Bissell carpet
sweeper. Spangler’s modifications of the Bissell sweeper led to his
own invention. On June 2, 1908, he received a patent for his Electric
Suction Sweeper. The device consisted of a cylindrical brush in the
front of the machine, a vertical-shaft electric motor above a fan in
the main body, and a pillowcase attached to a broom handle behind
the main body. The brush dislodged the dirt, which was sucked into
the pillowcase by the movement of air caused by a fan powered by
the electric motor. Although Spangler’s initial attempt to manufacture
and sell his machines failed, Spangler had, luckily for him, sold
one of his machines to a cousin, Susan Troxel Hoover, the wife of
William Henry Hoover.

834 / Vacuum cleaner
The Hoover family was involved in the production of leather
goods, with an emphasis on horse saddles and harnesses. William
Henry Hoover, president of the Hoover Company, recognizing that
the adoption of the automobile was having a serious impact on the
family business, was open to investigating another area of production.
In addition, Mrs. Hoover liked the Spangler machine that she
had been using for a couple of months, and she encouraged her husband
to enter into an agreement with Spangler. An agreement made
on August 5, 1908, allowed Spangler, as production manager, to
manufacture his machine with a small work force in a section of
Hoover’s plant. As sales of vacuum cleaners increased, what began
as a sideline for the Hoover Company became the company’s main
line of production.
Few American homes were wired for electricity when Spangler
and Hoover joined forces; not until 1920 did 35 percent of American
homes have electric power. In addition to this inauspicious fact, the
first Spangler-Hoover machine, the Model O, carried the relatively
high price of seventy-five dollars. Yet a full-page ad for the Model O
in the December, 1908, issue of the Saturday Evening Post brought a
deluge of requests. American women had heard of the excellent performance
of commercial vacuum cleaners, and they hoped that the
Hoover domestic model would do as well in the home.
Impact
As more and more homes in the United States and abroad became
wired for electric lighting, a clean and accessible power
source became available for household technologies. Whereas electric
lighting was needed only in the evening, the electrification of
household technologies made it necessary to use electricity during
the day. The electrification of domestic technologies therefore
matched the needs of the utility companies, which sought to maximize
the use of their facilities. They became key promoters of electric
appliances. In the first decades of the twentieth century, many
household technologies became electrified. In addition to fans and
vacuum cleaners, clothes-washing machines, irons, toasters, dishwashing
machines, refrigerators, and kitchen ranges were being
powered by electricity.

Vacuum cleaner / 835
The application of electricity to household technologies came as
large numbers of women entered the work force. During and after
World War I, women found new employment opportunities in industrial
manufacturing, department stores, and offices. The employment
of women outside the home continued to increase throughout the
twentieth century. Electrical appliances provided the means by which
families could maintain the same standards of living in the home while
both parents worked outside the home.
It is significant that Bissell was motivated by an allergy to dust
and Spangler by an asthmatic condition. The employment of the
carpet sweeper, and especially the electric vacuum cleaner, not only
H. Cecil Booth
Although Hubert Cecil Booth (1871-1955), an English civil
engineer, designed battleship engines, factories, and bridges, he
was not above working on homier problems when they intrigued
him. That happened in 1900 when he watched the demonstration
of a device that used forced air to blow the dirt out of
railway cars. It worked poorly, and the reason, it seemed to
Booth, was that blowing just stirred up the dirt. Sucking it into a
receptacle, he thought, would work better. He tested his idea by
placing a wet cloth over furniture upholstery and sucking through
it. The grime that collected on the side of the cloth facing the upholstery
proved him right.
He built his first vacuum cleaner—a term that he coined—in
1901. It cleaned houses, but only with considerable effort. Measuring
54 inches by 42 inches by 10 inches, it had to be carried in
a horse-driven van to the cleaning site. A team of workmen
from Booth’s Vacuum Cleaner Company then did the cleaning
with hoses that reached inside the house through windows and
doors. Moreover, the machine cost the equivalent of more than
fifteen hundred dollars. It was beyond the finances and physical
powers of home owners.
Booth marketed the first successful British one-person vacuum
cleaner, the Trolley-Vac, in 1906. Weighing one hundred
pounds, it was still difficult to wrestle into position, but it came
with hoses and attachments that made possible the cleaning of
different types of surfaces and hard-to-reach areas.

836 / Vacuum cleaner
made house cleaning more efficient and less physical but also led to
a healthier home environment. Whereas sweeping with a broom
tended only to move dust to a different location, the carpet sweeper
and the electric vacuum cleaner removed the dirt from the house.
See also Disposable razor; Electric refrigerator; Microwave cooking;
Robot (household); Washing machine.
Further Reading
Jailer-Chamberlain, Mildred. “This Is the Way We Cleaned Our
Floors.” Antiques & Collecting Magazine 101, no. 4 (June, 1996).
Kirkpatrick, David D. “The Ultimate Victory of Vacuum Cleaners.”
New York Times (April 14, 2001).
Shapiro, Laura. “Household Appliances.” Newsweek 130, no. 24A
(Winter, 1997/1998).

Vacuum tube
Vacuum tube
The invention: A sealed glass tube from which air and gas have
been removed to permit electrons to move more freely, the vacuum
tube was the heart of electronic systems until it was displaced
by transistors.
The people behind the invention:
Sir John Ambrose Fleming (1849-1945), an English physicist
and professor of electrical engineering
Thomas Alva Edison (1847-1931), an American inventor
Lee de Forest (1873-1961), an American scientist and inventor
Arthur Wehnelt (1871-1944), a German inventor
A Solution in Search of a Problem
837
The vacuum tube is a sealed tube or container from which almost
all the air has been pumped out, thus creating a near vacuum. When
the tube is in operation, currents of electricity are made to travel
through it. The most widely used vacuum tubes are cathode-ray
tubes (television picture tubes).
The most important discovery leading to the invention of the
vacuum tube was the Edison effect by Thomas Alva Edison in
1884. While studying why the inner glass surface of light bulbs
blackened, Edison inserted a metal plate near the filament of one
of his light bulbs. He discovered that electricity would flow from
the positive side of the filament to the plate, but not from the neg
ative side to the plate. Edison offered no explanation for the effect.
Edison had, in fact, invented the first vacuum tube, which was
later termed the diode; at that time there was no use for this device.
Therefore, the discovery was not recognized for its true significance.
A diode converts electricity that alternates in direction (alternating
current) to electricity that flows in the same direction (direct
current). Since Edison was more concerned with producing
direct current in generators, and not household electric lamps, he
essentially ignored this aspect of his discovery. Like many other in-

838 / Vacuum tube
ventions or discoveries that were ahead of their time—such as the
laser—for a number of years, the Edison effect was “a solution in
search of a problem.”
The explanation for why this phenomenon occurred would not
come until after the discovery of the electron in 1897 by Sir Joseph
John Thomson, an English physicist. In retrospect, the Edison effect
can be identified as one of the first observations of thermionic emission,
the freeing up of electrons by the application of heat. Electrons
were attracted to the positive charges and would collect on the positively
charged plate, thus providing current; but they were repelled
from the plate when it was made negative, meaning that no current
was produced. Since the diode permitted the electrical current to
flow in only one direction, it was compared to a valve that allowed a
liquid to flow in only one direction. This analogy is popular since
the behavior of water has often been used as an analogy for electricity,
and this is the reason that the term valves became popular for
vacuum tubes.
Same Device, Different Application
Sir John Ambrose Fleming, acting as adviser to the Edison Electric
Light Company, had studied the light bulb and the Edison effect
starting in the early 1880’s, before the days of radio. Many years
later, he came up with an application for the Edison effect as a radio
detector when he was a consultant for the Marconi Wireless Telegraph
Company. Detectors (devices that conduct electricity in one
direction only, just as the diode does, but at higher frequencies)
were required to make the high-frequency radio waves audible by
converting them from alternating current to direct current. Fleming
was able to detect radio waves quite effectively by using the Edison
effect. Fleming used essentially the same device that Edison had created,
but for a different purpose. Fleming applied for a patent on his
detector on November 16, 1904.
In 1906, Lee de Forest refined Fleming’s invention by adding a
zigzag piece of wire between the metal plate and the filament of the
vacuum tube. The zigzag piece of wire was later replaced by a
screen called a “grid.” The grid allowed a small voltage to control a
larger voltage between the filament and plate. It was the first com-

John Ambrose Fleming
Vacuum tube / 839
John Ambrose Fleming had a remarkably long and fruitful
scientific career. He was born in Lancaster, England, in 1849, the
eldest son of a minister. When he was a boy, the family moved
to London, which remained his home for the rest of his life. An
outstanding student, Fleming matriculated at University College,
London, graduating in 1870 with honors. Scholarships
took him to other colleges until his skill with electrical experiments
earned him a job as a lab instructor at Cambridge University
in 1880. In 1885, he returned to University College, London,
as professor of electrical technology. He taught there for the following
forty-one years, occasionally taking time off to serve as a
consultant for such electronics industry leaders as Thomas Edison
and Guglielmo Marconi.
Fleming’s passion was electricity and electronics, and he
was sought after as a teacher with a knack for memorable explanations.
For instance, he thought up the “right-hand” rule (also
called Fleming’s rule) to illustrate the relation of electromagnetic
forces during induction: When the thumb, index finger,
and middle finger of a human hand are held at right angles to
one another so that the thumb points in the direction of motion
through a magnetic field—which is indicated by the index finger—then
the middle finger shows the direction of induced
current. During his extensive research, Fleming investigated
transformers, high-voltage transmitters, electrical conduction,
cryogenic electrical effects, radio, and television, and also invented
the vacuum tube.
Advanced age hardly slowed him down. He wrote three
books and more than one hundred articles and remarried at
eighty-four. He also delivered public lectures—to audiences at
the Royal Institution and the Royal Society among other venues—
until he was ninety. He died in 1945, ninety-five years old,
having helped give birth to telecommunications.
plete vacuum tube and the first device ever constructed capable of
amplifying a signal—that is, taking a small-voltage signal and making
it much larger. He named it the “audion” and was granted a U.S.
patent in 1907.

840 / Vacuum tube
In 1907-1908, the American Navy carried radios equipped with
de Forest’s audion in its goodwill tour around the world. While useful
as an amplifier of the weak radio signals, it was not useful at this
point for the more powerful signals of the telephone. Other developments
were made quickly as the importance of the emerging
fields of radio and telephony were realized.
Impact
With many industrial laboratories working on vacuum tubes,
improvements came quickly. For example, tantalum and tungsten
filaments quickly replaced the early carbon filaments. In 1904, Arthur
Wehnelt, a German inventor, discovered that if metals were
coated with certain materials such as metal oxides, they emitted far
more electrons at a given temperature. These materials enabled
electrons to escape the surface of the metal oxides more easily. Thermionic
emission and, therefore, tube efficiencies were greatly improved
by this method.
Another important improvement in the vacuum tube came with
the work of the American chemist Irving Langmuir of the General
Electric Research Laboratory, starting in 1909, and Harold D. Arnold
of Bell Telephone Laboratories. They used new devices such as
the mercury diffusion pump to achieve higher vacuums. Working
independently, Langmuir and Arnold discovered that very high
vacuum used with higher voltages increased the power these tubes
could handle from small fractions of a watt to hundreds of watts.
The de Forest tube was now useful for the higher-power audio signals
of the telephone. This resulted in the introduction of the first
transamerican speech transmission in 1914, followed by the first
transatlantic communication in 1915.
The invention of the transistor in 1948 by the American physicists
William Shockley, Walter H. Brattain, and John Bardeen ultimately
led to the downfall of the tube. With the exception of the cathode-ray
tube, transistors could accomplish the jobs of nearly all vacuum tubes
much more efficiently. Also, the development of the integrated circuit
allowed the creation of small, efficient, highly complex devices that
would be impossible with radio tubes. By 1977, the major producers
of the vacuum tube had stopped making it.

See also Color television; FM radio; Radar; Radio; Radio crystal
sets; Television; Transistor; Transistor radio.
Further Reading
Vacuum tube / 841
Baldwin, Neil. Edison: Inventing the Century. Chicago: University of
Chicago Press, 2001.
Fleming, John Ambrose. Memories of a Scientific Life. London: Marshall,
Morgan & Scott, 1934.
Hijiya, James A. Lee de Forest and the Fatherhood of Radio. Bethlehem,
Pa.: Lehigh University Press, 1992.
Read, Oliver, and Walter L. Welch. From Tin Foil to Stereo: Evolution of
the Phonograph. 2d ed. Indianapolis: H. W. Sams, 1976.

842
Vat dye
Vat dye
The invention: The culmination of centuries of efforts to mimic the
brilliant colors displayed in nature in dyes that can be used in
many products.
The people behind the invention:
Sir William Henry Perkin (1838-1907), an English student in
Hofmann’s laboratory
René Bohn (1862-1922), a synthetic organic chemist
Karl Heumann (1850-1894), a German chemist who taught Bohn
Roland Scholl (1865-1945), a Swiss chemist who established the
correct structure of Bohn’s dye
August Wilhelm von Hofmann (1818-1892), an organic chemist
Synthesizing the Compounds of Life
From prehistoric times until the mid-nineteenth century, all dyes
were derived from natural sources, primarily plants. Among the
most lasting of these dyes were the red and blue dyes derived from
alizarin and indigo.
The process of making dyes took a great leap forward with the
advent of modern organic chemistry in the early years of the nineteenth
century. At the outset, this branch of chemistry, dealing with
the compounds of the element carbon and associated with living
matter, hardly existed, and synthesis of carbon compounds was not
attempted. Considerable data had accumulated showing that organic,
or living, matter was basically different from the compounds
of the nonliving mineral world. It was widely believed that although
one could work with various types of organic matter in
physical ways and even analyze their composition, they could be
produced only in a living organism.
Yet, in 1828, the German chemist Friedrich Wöhler found that it
was possible to synthesize the organic compound urea from mineral
compounds. As more chemists reported the successful preparation
of compounds previously isolated only from plants or animals,
the theory that organic compounds could be produced only in a living
organism faded.

One field ripe for exploration was that committed to exploiting the
uses of coal tar. Here, August Wilhelm von Hofmann was an active
worker. He and his students made careful studies of this complex
mixture. The high-quality stills they designed allowed for the isolation
of pure samples of important compounds for further study.
Of greater importance was the collection of able students Hofmann
attracted. Among them was Sir William Henry Perkin, who is regarded
as the founder of the dyestuffs industry. In 1856, Perkin undertook
the task of synthesizing quinine (a bitter crystalline alkaloid
used in medicine) from a nitrogen-containing coal tar material
called toluidine. Luck played a decisive role in the outcome of his
experiment. The sticky compound Perkin obtained contained no
quinine, so he decided to investigate the simpler related compound
aniline. A small amount of the impurity toluidine in his aniline gave
Perkin the first synthetic dye, Mauveine.
Searching for Structure
Vat dye / 843
From this beginning, the great dye industries of Europe, particularly
Germany, grew. The trial-and-error methods gave way to more
systematic searches as the structural theory of organic chemistry
was formulated.
As the twentieth century began, great progress had been made,
and German firms dominated the industry. Badische Anilin- und
Soda-Fabrik (BASF) was incorporated at Ludwigshafen in 1865 and
undertook extensive explorations of both alizarin and indigo. A
chemist, René Bohn, had made important discoveries in 1888, which
helped the company recover lost ground in the alizarin field. In
1901, he undertook the synthesis of a dye he hoped would combine
the desirable attributes of both alizarin and indigo.
As so often happens in science, nothing like the expected occurred.
Bohn realized that the beautiful blue crystals that resulted
from his synthesis represented a far more important product. Not
only was this the first synthetic vat dye, Indanthrene, ever prepared,
but also, by studying the reaction at higher temperature, a useful
yellow dye, Flavanthrone, could be produced.
The term vat dye is used to describe a method of applying the dye,
but it also serves to characterize the structure of the dye, because all

844 / Vat dye
William Henry Perkin
Born in England in 1838, William Henry Perkin saw a chemical
experiment for the first time when he was a small boy. He
found his calling there and then, much to the dismay of his father,
who wanted him to be a builder and architect like himself.
Perkin studied chemistry every chance he found as a teenager
and was only seventeen when he won an appointment as
the assistant to the German chemist August Wilhelm von Hofmann.
A year later, while trying to synthesize quinine at Hofmann’s
suggestion, Perkin discovered a deep purple dye—now
known as aniline purple or Mauveine, but popularly called
mauve. In 1857 he opened a small dyeworks by the Grand
Union Canal in West London, hoping to make his fortune by
manufacturing the dye.
He succeeded brilliantly. His ambitions were helped along
royally when Queen Victoria wore a silk gown dyed with Mauveine
to the Royal Exhibition of 1862. In 1869, he perfected a
method for producing another new dye, alizarin, which is red.
A wealthy man, he sold his business in 1874 when he was just
thirty-six years old and devoted himself to research, which included
isolation of the first synthetic perfume, coumarin, from
coal tar.
Perkin died in 1907, a year after receiving a knighthood, one
of his many awards and honors for starting the artificial dye industry.
His son William Henry Perkin, Jr. (1860-1927) also became
a well-known researcher in organic chemistry.
currently useful vat dyes share a common unit. One fundamental
problem in dyeing relates to the extent to which the dye is watersoluble.
A beautifully colored molecule that is easily soluble in water
might seem attractive given the ease with which it binds with the fiber;
however, this same solubility will lead to the dye’s rapid loss in
daily use.
Vat dyes are designed to solve this problem by producing molecules
that can be made water-soluble, but only during the dyeing or
vatting process. This involves altering the chemical structure of the
dye so that it retains its color throughout the life of the cloth.
By 1907, Roland Scholl had showed unambiguously that the

chemical structure proposed by Bohn for Indanthrene was correct,
and a major new area of theoretical and practical importance was
opened for organic chemists.
Impact
Bohn’s discovery led to the development of many new and useful
dyes. The list of patents issued in his name fills several pages in
Chemical Abstracts indexes.
The true importance of this work is to be found in a consideration
of all synthetic chemistry, which may perhaps be represented by
this particular event. More than two hundred dyes related to Indanthrene
are in commercial use. The colors represented by these substances
are a rainbow making nature’s finest hues available to all.
The dozen or so natural dyes have been synthesized into more than
seven thousand superior products through the creativity of the
chemist.
Despite these desirable outcomes, there is doubt whether there is
any real benefit to society from the development of new dyes. This
doubt is the result of having to deal with limited natural resources.
With so many urgent problems to be solved, scientists are not sure
whether to search for greater luxury. If the field of dye synthesis reveals
a single theme, however, it must be to expect the unexpected.
Time after time, the search for one goal has led to something quite
different—and useful.
See also Buna rubber; Color film; Neoprene.
Further Reading
Vat dye / 845
Clark, Robin J. H., et al. “Indigo, Woad, and Tyrian Purple: Important
Vat Dyes from Antiquity to the Present.” Endeavour 17, no. 4
(December, 1993).
Farber, Eduard. The Evolution of Chemistry: A History of Its Ideas,
Methods, and Materials. 2d ed. New York: Ronald Press, 1969.
Partington, J. R. A History of Chemistry. Staten Island, N.Y.: Martino,
1996.
Schatz, Paul F. “Anniversaries: 2001.” Journal of Chemical Education
78, no. 1 (January, 2001).

846
Velcro
Velcro
The invention: A material comprising millions of tiny hooks and
loops that work together to create powerful and easy-to-use fasteners
for a wide range of applications.
The person behind the invention:
Georges de Mestral (1904-1990), a Swiss engineer and inventor
From Cockleburs to Fasteners
Since prehistoric times, people have walked through weedy fields
and arrived at home with cockleburs all over their clothing. In 1948, a
Swiss engineer and inventor, Georges de Mestral, found his clothing
full of cockleburs after walking in the Swiss Alps near Geneva. Wondering
why cockleburs stuck to clothing, he began to examine them
under a microscope. De Mestral’s initial examination showed that
each of the thousands of fibrous ends of the cockleburs was tipped
with a tiny hook; it was the hooks that made the cockleburs stick to
fabric. This observation, combined with much subsequent work, led
de Mestral to invent velcro, which was patented in 1957 in the form of
two strips of nylon material. One of the strips contained millions of
tiny hooks, while the other contained a similar number of tiny loops.
When the two strips were pushed together, the hooks were inserted
into the loops, joining the two strips of nylon very firmly. This design
makes velcro extremely useful as a material for fasteners that is used
in applications ranging from sneaker fasteners to fasteners used to
join heart valves during surgery.
Making Velcro Practical
Velcro is not the only invention credited to de Mestral, who also
invented such items as a toy airplane and an asparagus peeler, but it
was his greatest achievement. It is said that his idea for the material
was partly the result of a problem his wife had with a jammed dress
zipper just before an important social engagement. De Mestral’s
idea was to design a sort of locking tape that used the hook-andloop
principle that he had observed under the microscope. Such a

tape, he believed, would never jam. He also believed that the tape
would do away with such annoyances as buttons that popped open
unexpectedly and knots in shoelaces that refused to be untied.
The design of the material envisioned by de Mestral took seven
years of painstaking effort. When it was finished, de Mestral named
it “velcro” (a contraction of the French phrase velvet crochet, meaning
velvet hook), patented it, and opened a factory to manufacture
it. Velcro’s design required that de Mestral identify the optimal
number of hooks and loops to be used. He eventually found that using
approximately three hundred per square inch worked best. In
addition, his studies showed that nylon was an excellent material
for his purposes, although it had to be stiffened somewhat to work
well. Much additional experimentation showed that the most effective
way of producing the necessary stiffening was to subject the
velcro to infrared light after manufacturing it.
Other researchers have demonstrated that velcrolike materials
need not be made of nylon. For example, a new micromechanical
velcrolike material (microvelcro) that medical researchers believe
will soon be used to hold together blood vessels after surgery is
made of minute silicon loops and hooks. This material is thought to
be superior to other materials for such applications because it will
not be redissolved prematurely by the body. Other uses for microvelcro
may be to hold together tiny electronic components in miniaturized
computers without the use of glue or other adhesives. A major
advantage of the use of microvelcro in such situations is that it is
resistant to changes of temperature as well as to most chemicals that
destroy glue and other adhesives.
Impact
Velcro / 847
In 1957, when velcro was patented, there were four main ways to
hold things together. These involved the use of buttons, laces, snaps,
and zippers (which had been invented by Chicagoan Whitcomb L.
Judson in 1892). All these devices had drawbacks; zippers can jam,
buttons can come open at embarrassing times, and shoelaces can
form knots that are difficult to unfasten. Almost immediately after
velcro was introduced, its use became widespread; velcro fasteners
can be found on or in clothing, shoes, watchbands, wallets, back-

848 / Velcro
packs, bookbags, motor vehicles, space suits, blood-pressure cuffs,
and in many other places. There is even a “wall jumping” game incorporating
velcro in which a wall is covered with a well-supported
piece of velcro. People who want to play put on jackets made of
velcro and jump as high as they can. Wherever they land on the wall,
the velcro will join together, making them stick.
Wall jumping, silly though it may be, demonstrates the tremendous
holding power of velcro; a velcro jacket can keep a twohundred-pound
person suspended from a wall. This great strength is
used in a more serious way in the design of the items used to anchor
astronauts to space shuttles and to buckle on parachutes. In addition,
velcro is washable, comes in many colors, and will not jam. No
doubt many more uses for this innovative product will be found.
See also Artificial heart.
Georges de Mestral
Georges de Mestral got his idea for Velcro in part during a
hunting trip on his estates and in part before an important formal
social function. These contexts are evidence of the high
standing in Swiss society held by de Mestral, an engineer and
manufacturer. In fact, de Mestral, who was born in 1904, came
from a illustrious line of noble landowners. Their prize possession
was one of Switzerland’s famous residences, the castle of
Saint Saphorin on Morges.
Built on the site of yet older fortifications, the castle was
completed by François-Louis de Pesme in 1710. An enemy of
King Louis XIV, de Pesme served in the military forces of Austria,
Holland, and England, rising to the rank of lieutenant general,
but he is best known for driving off a Turkish invasion fleet
on the Danube in 1695. Other forebears include the diplomat
Armand- François Louis de Mestral (1738-1805) and his father,
Albert-Georges-Constantin de Mestral (1878-1966), an agricultural
engineer.
The castle passed to the father’s four sons and eventually
into the care of the inventor. It in turn was inherited by Georges
de Mestral’s sons Henri and François when he died in 1990 in
Genolier, Switzerland.

Further Reading
Velcro / 849
“George De Mestral: Inventor of Velcro Fastener.” Los Angeles Times
(February 13, 1990).
LaFavre Yorks, Cindy. “Hidden Helpers Velcro Fasteners, Pull-On
Loops and Other Extras Make Dressing Easier for People with
Disabilities.” Los Angeles Times (November 1, 1991).
Roberts, Royston M., and Jeanie Roberts. Lucky Science: Accidental
Discoveries from Gravity to Velcro, with Experiments. New York:
John Wiley, 1994.
Stone, Judith. “Stuck on Velcro!” Reader’s Digest (September, 1988).
“Velcro-wrapped Armor Saves Lives in Bosnia.” Design News 52, no.
7 (April 7, 1997).

850
Vending machine slug rejector
Vending machine slug rejector
The invention: A device that separates real coins from counterfeits,
the slug rejector made it possible for coin-operated vending
machines to become an important marketing tool for many
products
The people behind the invention:
Thomas Adams, the founder of Adams Gum Company
Frederick C. Lynde, an Englishman awarded the first American
patent on a vending machine
Nathaniel Leverone (1884-1969), a founder of the Automatic
Canteen Company of America
Louis E. Leverone (1880-1957), a founder, with his brother, of the
Automatic Canteen Company of America
The Growth of Vending Machines
One of the most imposing phenomena to occur in the United
States economy following World War II was the growth of vending
machines. Following the 1930’s invention and perfection of the slug
rejector, vending machines became commonplace as a means of
marketing gum and candy. By the 1960’s, almost every building had
soft drink and coffee machines. Street corners featured machines
that dispensed newspapers, and post offices even used vending machines
to sell stamps. Occasionally someone fishing in the backwoods
could find a vending machine next to a favorite fishing hole
that would dispense a can of fishing worms upon deposit of the correct
amount of money. The primary advantage offered by vending
machines is their convenience. Unlike people, machines can provide
goods and services around the clock, with no charge for the “labor”
of standing duty.
The decade of the 1950’s brought not only an increase in the number
of vending machines but also an increase in the types of goods
that were marketed through them. Before World War II, the major
products had been cigarettes, candy, gum, and soft drinks. The
1950’s brought far more products into the vending machine market.

Vending machine slug rejector / 851
The first recognized vending machine in history was invented in
the third century b.c.e. by the mathematician Hero. This first machine
was a coin-activated device that dispensed sacrificial water in
an Egyptian temple. It was not until the year 1615 that another
vending machine was recorded. In that year, snuff and tobacco
vending boxes began appearing in English pubs and taverns. These
tobacco boxes were less sophisticated machines than was Hero’s,
since they left much to the honesty of the customer. Insertion of a
coin opened the box; once it was open, the customer could take out
as much tobacco as desired. One of the first United States patents on
a machine was issued in 1886 to Frederick C. Lynde. That machine
was used to vend postcards.
If any one person can be considered the father of vending machines
in the United States, it would probably be Thomas Adams,
the founder of Adams Gum Company. Adams began the first successful
vending operation in America in 1888 when he placed gum
machines on train platforms in New York City.
Other early vending machines included scales (which vended a
service rather than a product), photograph machines, strength testers,
beer machines, and hot water vendors (to supply poor people
who had no other source of hot water). These were followed, around
1900, by complete automatic restaurants in Germany, cigar vending
machines in Chicago, perfume machines in Paris, and an automatic
divorce machine in Utah.
Also around 1900 came the introduction of coin-operated gambling
machines. These “slot machines” are differentiated from normal
vending machines. The vending machine industry does not
consider gambling machines to be a part of the vending industry
since they do not vend merchandise. The primary importance of the
gambling machines was that they induced the industry to do research
into slug rejection. Early machines allowed coins to be retrieved
by the use of strings tied to them and accepted counterfeit
lead coins, called slugs. It was not until the 1930’s that the slug
rejector was perfected. Invention of the slug rejection device gave
rise to the tremendous growth in the vending machine industry in
the 1930’s by giving vendors more confidence that they would be
paid for their products or services.
Soft drink machines got their start just prior to the beginning of

852 / Vending machine slug rejector
the twentieth century. By 1906, improved models of these machines
could dispense up to ten different flavors of soda pop. The
drinks were dispensed into a drinking glass or tin cup that was
placed near the machine (there was usually only one glass or cup
to a machine, since paper cups had not been invented). Public
health officials became concerned that everyone was drinking
from the same cup. At that point, someone came up with the idea
of setting a bucket of water next to the machine so that each customer
could rinse off the cup before drinking from it. The year 1909
witnessed one of the monumental inventions in the history of
vending machines, the pay toilet.
Impact
The 1930’s witnessed improved vending machines. Slug rejectors
were the most important introduction. In addition, change-making
machines were instituted, and a few machines would even say
“thank you” after a coin was deposited. These improved machines
led many marketers to experiment with automatic vending. Coinoperated
washing machines were one of the new applications of the
1930’s. During the Depression, many appliance dealers attached
coin metering devices to washing machines, allowing the user to accumulate
money to make the monthly payments by using the appliance.
This was a form of forced saving. It was not long before some
enterprising appliance dealer got the idea of placing washing machines
in apartment house basements. This idea was soon followed
by stores full of coin-operated laundry machines, giving rise to a
new kind of automatic vending business.
Following World War II, there was a surge of innovation in the
vending machine industry. Much of that surge resulted from the
discovery of vending machines by industrial management. Prior to
the war, the managements of most factories had been tolerant of
vending machines. Following the war, managers discovered that
the machines could be an inexpensive means of keeping workers
happy. They became aware that worker productivity could be increased
by access to candy bars or soft drinks. As a result, the demand
for machines exceeded the supply offered by the industry
during the late 1940’s.

Vending machines have had a surprising effect on the total retail
sales of the U.S. economy. In 1946, sales through vending machines
totaled $600 million. By 1960, that figure had increased to $2.5 billion;
by 1970, it exceeded $6 billion. The decade of the 1950’s began
with individual machines that would dispense cigarettes, candy,
gum, coffee, and soft drinks. By the end of that decade, it was much
more common to see vending machines in groups. The combination
of machines in a group could, in many cases, meet the requirements
to assemble a complete meal.
Convenience is the key to the popularity of vending machines.
Their ability to sell around the clock has probably been the major
impetus to vending machine sales as opposed to more conventional
marketing. Lower labor costs have also played a role in their popularity,
and their location in areas of dense pedestrian traffic prompts
impulse purchases.
Despite the advances made by the vending machine industry
during the 1950’s, there was still one major limitation to growth, to
be solved during the early 1960’s. That problem was that vending
machines were effectively limited to low-priced items, since the machines
would accept nothing but coins. The inconvenience of inserting
many coins kept machine operators from trying to market expensive
items; as they expected consumer reluctance. The early
1960’s witnessed the invention of vending machines that would accept
and make change for $1, $5, and $10 bills. This invention paved
the way for expansion into lines of grocery items and tickets.
The first use of vending machines to issue tickets was at an Illinois
race track, where pari-mutuel tickets were dispensed upon deposit of
$2. Penn Central Railroad was one of the first transportation companies
to sell tickets by means of vending machines. These machines,
used in high-traffic areas on the East Coast, permitted passengers to
deal directly with a computer when buying reserved-seat train tickets.
The machines would accept $1 bills and $5 bills as well as coins.
Limitations to Vending Machines
Vending machine slug rejector / 853
There are limitations to the use of vending machines. Primary
among these are mechanical failure and vandalism of machines.
Another limitation often mentioned is that not every product can be

854 / Vending machine slug rejector
sold by machine. There are several factors that make some goods
more vendable than others. National advertising and wide consumer
acceptance help. Product must have a high turnover in order
to justify the cost of a machine and the cost of servicing it. A third
factor in measuring the potential success of an item is where it will
be consumed or used. The most successful products are used within
a short distance of the machine; consumers must be made willing to
pay the usually higher prices of machine-bought products by the
convenience of machine location.
The automatic vending of merchandise plays the largest role in
the vending machine industry, but the vending of services also
plays a role. The largest percentage of service vending comes from
coin laundries. Other types of services are vended by weighing machines,
parcel lockers, and pay toilets. By depositing a coin, a person
can even get shoes shined. Some motel beds offer a “massage.” Even
the lowly parking meter is an example of a vending machine that
dispenses services. Coin-operated photocopy machines account for
a large portion of service vending.
A later advance in the vending machine industry is the use of
credit. The cashless society began to make strides with vending machines
as well as conventional vendors. As of the early 1990’s, credit
cards could be used to operate only a few types of vending machines,
primarily those that dispense transportation tickets. Vending machines
operated by banks dispense money upon deposit of a credit
card. Credit-card gasoline pumps reduced labor requirements at gasoline
stations, pushing the concept of self-service a step further. As
credit card transactions become more common in general and as the
cost of making them falls, use of credit cards for vending machines
will increase.
Thousands of items have been marketed through vending machines,
and firms must continue to evaluate the use of automatic retailing
as a marketing channel. Many products are not conducive to
automatic vending, but before dismissing that option for a particular
product, a marketer should consider the range of products sold
through vending machines. The producers of Band-Aid flexible plastic
bandages saw the possibilities in the vending field. The only product
modification necessary was to put Band-Aids in a package the
size of a candy bar, able to be sold from renovated candy machines.

The next problem was to determine areas where there would be a
high turnover of Band-Aids. Bowling alleys were an obvious answer,
since many bowlers suffered from abrasions on their fingers.
The United States is not alone in the development of vending machines;
in fact, it is not as advanced as some nations of the world. In
Japan, machines operated by credit cards have been used widely
since the mid-1960’s, and the range of products offered has been
larger than in the United States. Western Europe is probably the
most advanced area of the world in terms of vending machine technology.
Germany of the early 1990’s probably had the largest selection
of vending machines of any European country. Many gasoline
stations in Germany featured beer dispensing machines. In rural areas
of the country, vending machines hung from utility poles. These
rural machines provided candy and gum, among other products, to
farmers who did not often travel into town.
Most vending machine business in Europe was done not in individual
machines but in automated vending shops. The machines offered
a creative solution to obstacles created by regulations and
laws. Some countries had laws stating that conventional retail stores
could not be open at night or on Sundays. To increase sales and satisfy
consumer needs, stores built vending operations that could be
used by customers during off hours. The machines, or combinations
of them, often stocked a tremendous variety of items. At one German
location, consumers could choose among nearly a thousand
grocery items.
The Future
Vending machine slug rejector / 855
The future will see a broadening of product lines offered in vending
machines as marketers come to recognize the opportunities that
exist in automatic retailing. In the United States, vending machines
of the early 1990’s primarily dispensed products for immediate consumption.
If labor costs increase, it will become economically feasible
to sell more items from vending machines. Grocery items and
tickets offered the most potential for expansion.
Vending machines offer convenience to the consumer. Virtually
any company that produces for the retail market must consider
vending machines as a marketing channel. Machines offer an alter-

856 / Vending machine slug rejector
native to conventional stores that cannot be ignored as the range of
products offered through machines increases.
Vending machines appear to be a permanent fixture and have
only scratched the surface of the market. Although machines have a
long history, their popularization came from innovations of the
1930’s, particularly the slug rejector. Marketing managers came to
recognize that vending machine sales are more than a sideline. Increasingly,
firms established separate departments to handle sales
through vending machines. Successful companies make the best
use of all channels of distribution, and vending machines had become
an important marketing channel.
See also Geiger counter; Sonar; Radio interferometer.
Further Reading
Ho, Rodney. “Vending Machines Make Change—-Now They Sell
Movie Soundtracks, Underwear—Even Art.” Wall Street Journal
(July 7, 1999).
Rosen, Cheryl. “Vending Machines Get a High-Tech Makeover.
Informationweek 822 (January 29, 2001).
Ryan, James. “In Vending Machine, Brains That Tell Good Money
from Bad.” New York Times (April 8, 1999).
Tagliabue, John. “Vending Machines Face an Upheaval of Change.”
New York Times (February 16, 1999).

Videocassette recorder
Videocassette recorder
The invention: A device for recording and playing back movies
and television programs, the videocassette recorder (VCR) revolutionized
the home entertainment industry in the late 1970’s.
The company behind the invention:
Philips Corporation, a Dutch Company
Videotape Recording
857
Although television sets first came on the market before World
War II, video recording on magnetic tape was not developed until
the 1950’s. Ampex marketed the first practical videotape recorder
in 1956. Unlike television, which manufacturers aimed at retail
consumers from its inception, videotape recording was never expected
to be attractive to the individual consumer. The first videotape
recorders were meant for use within the television industry.
Developed not long after the invention of magnetic tape recording
of audio signals, the early videotape recorders were large machines
that employed an open reel-to-reel tape drive similar to that
of a conventional audiotape recorder. Recording and playback heads
scanned the tape longitudinally (lengthwise). Because video signals
have a much wider frequency (“frequency” is the distance between
the tops and the bottoms of the signal waves) than audio signals do,
this scanning technique meant that the amount of recording time
available on one reel of tape was extremely limited. In addition,
open reels were large and awkward, and the magnetic tape itself
was quite expensive.
Still, within the limited application area of commercial television,
videotape recording had its uses. It made it possible to play
back recorded material immediately rather than having to wait for
film to be processed in a laboratory. As television became more popular
and production schedules became more hectic, with more material
being produced in shorter and shorter periods of time, videotape
solved some significant problems.

858 / Videocassette recorder
Helical Scanning Breakthrough
Engineers in the television industry continued to search for innovations
and improvements in videotape recording following
Ampex’s marketing of the first practical videotape recorder in the
1950’s. It took more than ten years, however, for the next major
breakthrough to occur. The innovation that proved to be the key to
reducing the size and awkwardness of video recording equipment
came in 1967 with the invention by the Philips Corporation of helical
scanning.
All videocassette recorders eventually employed multiple-head
helical scanning systems. In a helical scanning system, the record
and playback heads are attached to a spinning drum or head that rotates
at exactly 1,800 revolutions per minute, or 30 revolutions per
second. This is the number of video frames per second used in the
NTSC-TV broadcasts in the United States and Canada. The heads
are mounted in pairs 180 degrees apart on the drum. Two fields on
the tape are scanned for each revolution of the drum. Perhaps the
easiest way to understand the helical scanning system is to visualize
the spiral path followed by the stripes on a barber’s pole.
Helical scanning deviated sharply from designs based on audio
recording systems. In an audiotape recorder, the tape passes over
stationary playback and record heads; in a videocassette recorder,
both the heads and the tape move. Helical scanning is, however, one
of the few things that competing models and formats of videocassette
recorders have in common. Different models employ different
tape delivery systems and, in the case of competing formats such as
Beta and VHS, there may be differences in the composition of the
video signal to be recorded. Beta uses a 688-kilohertz (kHz) frequency,
while VHS employs a frequency of 629 kHz. This difference
in frequency is what allows Beta videocassette recorders (VCRs) to
provide more lines of resolution and thus a superior picture quality;
VHS provides 240 lines of resolution, while Beta has 400. (For this
reason, it is perhaps unfortunate that the VHS format eventually
dominated the market.)
In addition to helical scanning, Philips introduced another innovation:
the videocassette. Existing videotape recorders employed a
reel-to-reel tape drive, as do videocassettes, but videocassettes en-

close the tape reels in a protective case. The case prevents the tape
from being damaged in handling.
The first VCRs were large and awkward compared to later models.
Industry analysts still thought that the commercial television
and film industries would be the primary markets for VCRs. The
first videocassettes employed wide— 3 4-inch or 1-inch—videotapes,
and the machines themselves were cumbersome. Although Philips
introduced a VCR in 1970, it took until 1972 before the machines actually
became available for purchase, and it would be another ten
years before VCRs became common appliances in homes.
Consequences
Videocassette recorder / 859
Following the introduction of the VCR in 1970, the home entertainment
industry changed radically. Although the industry did not
originally anticipate that the VCR would have great commercial potential
as a home entertainment device, it quickly became obvious
that it did. By the late 1970’s, the size of the cassette had been reduced
and the length of recording time available per cassette had
been increased from one hour to six. VCRs became so widespread
that advertisers on television became concerned with a phenomenon
known as “timeshifting,” which refers to viewers setting the
VCR to record programs for later viewing. Jokes about the complexity
of programming VCRs appeared in the popular culture, and an
inability to cope with the VCR came to be seen as evidence of technological
illiteracy.
Consumer demand for VCRs was so great that, by the late 1980’s,
compact portable video cameras became widely available. The same
technology—helical scanning with multiple heads—was successfully
miniaturized, and “camcorders” were developed that were not much
larger than a paperback book. By the early 1990’s, “reality television”—that
is, television shows based on actual events—began relying
on video recordings supplied by viewers rather than material
produced by professionals. The video recorder had completed a circle:
It began as a tool intended for use in the television studio, and it
returned there four decades later. Along the way, it had an effect no
one could have predicted; passive viewers in the audience had evolved
into active participants in the production process.

860 / Videocassette recorder
See also Cassette recording; Color television; Compact disc;
Dolby noise reduction; Television; Walkman cassette player.
Further Reading
Gilder, George. Life After Television. New York: W. W. Norton, 1992.
Lardner, James. Fast Forward: Hollywood, the Japanese, and the Onslaught
of the VCR. New York: Norton, 1987.
Luther, Arch C. Digital Video in the PC Environment. New York:
McGraw-Hill, 1989.
Wassser, Frederick. Veni, Vidi, Video: The Hollywood Empire and the
VCR. Austin: University of Texas Press, 2001.

Virtual machine
Virtual machine
The invention: The first computer to swap storage space between
its random access memory (RAM) and hard disk to create a
larger “virtual” memory that enabled it to increase its power.
The people behind the invention:
International Business Machines (IBM) Corporation, an
American data processing firm
Massachusetts Institute of Technology (MIT), an American
university
Bell Labs, the research and development arm of the American
Telephone and Telegraph Company
A Shortage of Memory
861
During the late 1950’s and the 1960’s, computers generally used
two types of data storage areas. The first type, called “magnetic
disk storage,” was slow and large, but its storage space was relatively
cheap and abundant. The second type, called “main memory”
(also often called “random access memory,” or RAM), was
much faster. Computation and program execution occurred primarily
in the “central processing unit” (CPU), which is the “brain”
of the computer. The CPU accessed RAM as an area in which to
perform intermediate computations, store data, and store program
instructions.
To run programs, users went through a lengthy process. At that
time, keyboards with monitors that allowed on-line editing and
program storage were very rare. Instead, most users used typewriter-like
devices to type their programs or text on paper cards.
Holding decks of such cards, users waited in lines to use card readers.
The cards were read and returned to the user, and the programs
were scheduled to run later. Hours later or even overnight,
the output of each program was printed in some predetermined
order, after which all the outputs were placed in user bins. It might
take as long as several days to make any program corrections that
were necessary.

862 / Virtual machine
Because CPUs were expensive, many users had to share a single
CPU. If a computer had a monitor that could be used for editing or
could run more than one program at a time, more memory was required.
RAM was extremely expensive, and even multimilliondollar
computers had small memories. In addition, this primitive
RAM was extremely bulky.
Virtually Unlimited Memory
The solution to the problem of creating affordable, convenient
memory came in a revolutionary reformulation of the relationship
between main memory and disk space. Since disk space was large
and cheap, it could be treated as an extended “scratch pad,” or temporary-use
area, for main memory. While a program ran, only small
parts of it (called pages or segments), normally the parts in use at
that moment, would be kept in the main memory. If only a few
pages of each program were kept in memory at any time, more programs
could coexist in memory. When pages lay idle, they would be
sent from RAM to the disk, as newly requested pages were loaded
from the disk to the RAM. Each user and program “thought” it had
essentially unlimited memory (limited only by disk space), hence
the term “virtual memory.”
The system did, however, have its drawbacks. The swapping and
paging processes reduced the speed at which the computer could
process information. Coordinating these activities also required
more circuitry. Integrating each program and the amount of virtual
memory space it required was critical. To keep the system operating
accurately, stably, and fairly among users, all computers have an
“operating system.” Operating systems that support virtual memory
are more complex than the older varieties are.
Many years of research, design, simulations, and prototype testing
were required to develop virtual memory. CPUs and operating
systems were designed by large teams, not individuals. Therefore,
the exact original discovery of virtual memory is difficult to trace.
Many people contributed at each stage.
The first rudimentary implementation of virtual memory concepts
was on the Atlas computer, which was constructed in the early
1960’s in England, at the University of Manchester. It coupled RAM

Virtual machine / 863
with a device that read a magnetizable cylinder, or drum, which
meant that it was a two-part storage system.
In the late 1960’s, the Massachusetts Institute of Technology
(MIT), Bell Telephone Labs, and the General Electric Company
(later Honeywell) jointly designed a high-level operating system
called MULTICS, which had virtual memory.
During the 1960’s, IBM worked on virtual memory, and the IBM
360 series supported the new memory system. With the evolution
of engineering concepts such as circuit integration, IBM produced
a new line of computers called the IBM 370 series. The IBM 370
supported several advances in hardware (equipment) and software
(program instructions), including full virtual memory capabilities.
It was a platform for a new and powerful “environment,”
or set of conditions, in which software could be run; IBM called
this environment the VM/370. The VM/370 went far beyond virtual
memory, using virtual memory to create virtual machines. In a
virtual machine environment, each user can select a separate and
complete operating system. This means that separate copies of operating
systems such as OS/360, CMS, DOS/360, and UNIX can all
run in separate “compartments” on a single computer. In effect,
each operating system has its own machine. Reliability and security
were also increased. This was a major breakthrough, a second
computer revolution.
Another measure of the significance of the IBM 370 was the commercial
success and rapid, widespread distribution of the system.
The large customer base for the older IBM 360 also appreciated the
IBM 370’s compatibility with that machine. The essentials of the
IBM 370 virtual memory model were retained even in the 1990’s
generation of large, powerful mainframe computers. Furthermore,
its success carried over to the design decisions of other computers in
the 1970’s.
The second-largest computer manufacturer, Digital Equipment
Corporation (DEC), followed suit; its popular VAX minicomputers
had virtual memory in the late 1970’s. The celebrated UNIX operating
system also added virtual memory. IBM’s success had led to industry-wide
acceptance.

864 / Virtual machine
Consequences
The impact of virtual memory extends beyond large computers
and the 1970’s. During the late 1970’s and early 1980’s, the computer
world took a giant step backward. Small, single-user computers
called personal computers (PCs) became very popular. Because
they were single-user models and were relatively cheap,
they were sold with weak CPUs and deplorable operating systems
that did not support virtual memory. Only one program could run
at a time. Larger and more powerful programs required more
memory than was physically installed. These computers crashed
often.
Virtual memory raises PC user productivity. With virtual memory
space, during data transmissions or long calculations, users can
simultaneously edit files if physical memory runs out. Most major
PCs now have improved CPUs and operating systems, and these
advances support virtual memory. Popular virtual memory systems
such as OS/2, Windows/DOS, and MAC-OS are available. Even old
virtual memory UNIX has been used in PCs.
The concept of a virtual machine has been revived, in a weak
form, on PCs that have dual operating systems (such as UNIX and
DOS, OS/2 and DOS, MAC and DOS, and UNIX and DOS combinations).
Most powerful programs benefit from virtual memory. Many
dazzling graphics programs require massive RAM but run safely in
virtual memory. Scientific visualization, high-speed animation, and
virtual reality all benefit from it. Artificial intelligence and computer
reasoning are also part of a “virtual” future.
See also Colossus computer; Differential analyzer; ENIAC computer;
IBM Model 1401 computer; Personal computer; Robot (industrial);
SAINT; Virtual reality.
Further Reading
Bashe, Charles J. IBM’s Early Computers. Cambridge, Mass.: MIT
Press, 1986.
Ceruzzi, Paul E. A History of Modern Computing. Cambridge, Mass.:
MIT Press, 2000.

Virtual machine / 865
Chposky, James, and Ted Leonsis. Blue Magic: The People, Power, and
Politics Behind the IBM Personal Computer. New York: Facts on File,
1988.
Seitz, Frederick, and Norman G. Einspruch. Electronic Genie: The
Tangled History of Silicon. Urbana: University of Illinois Press,
1998.

866
Virtual reality
Virtual reality
The invention: The creation of highly interactive, computer-based
multimedia environments in which the user becomes a participant
with the computer in a “virtually real” world.
The people behind the invention:
Ivan Sutherland (1938- ), an American computer scientist
Myron W. Krueger (1942- ), an American computer scientist
Fred P. Brooks (1931- ), an American computer scientist
Human/Computer Interface
In the early 1960’s, the encounter between humans and computers
was considered to be the central event of the time. The computer
was evolving more rapidly than any technology in history; humans
seemed not to be evolving at all. The “user interface” (the devices
and language with which a person communicates with a computer)
was a veneer that had been applied to the computer to make it
slightly easier to use, but it seemed obvious that the ultimate interface
would be connecting the human body and senses directly to the
computer.
Against this background, Ivan Sutherland of the University of
Utah identified the next logical step in the development of computer
graphics. He implemented a head-mounted display that allowed
a person to look around in a graphically created “room” simply
by turning his or her head. Two small cathode-ray tubes, or
CRTs (which are the basis of television screens and computer monitors),
driven by vector graphics generators (mathematical imagecreating
devices) provided the appropriate view for each eye, and
thus, stereo vision.
In the early 1970’s, Fred P. Brooks of the University of North Carolina
created a system that allowed a person to handle graphic objects
by using a mechanical manipulator. When the user moved the
physical manipulator, a graphic manipulator moved accordingly. If
a graphic block was picked up, the user felt its weight and its resistance
to his or her fingers closing around it.

A New Reality
Virtual reality / 867
Beginning in 1969, Myron W. Krueger of the University of Wisconsin
created a series of interactive environments that emphasized
unencumbered, full-body, multisensory participation in computer
events. In one demonstration, a sensory floor detected participants’
movements around a room. A symbol representing each participant
moved through a projected graphic maze that changed in playful
ways if participants tried to cheat. In another demonstration, participants
could use the image of a finger to draw on the projection
screen. In yet another, participants’ views of a projected threedimensional
room changed appropriately as they moved around
the physical space.
It was interesting that people naturally accepted these projected
experiences as reality. They expected their bodies to influence graphic
objects and were delighted when they did. They regarded their electronic
images as extensions of themselves. What happened to their
images also happened to them; they felt what touched their images.
These observations led to the creation of the Videoplace, a graphic
world that people could enter from different places to interact with
each other and with graphic creatures. Videoplace is an installation
at the Connecticut Museum of Natural History in Storrs, Connecticut.
Videoplace visitors in separate rooms can fingerpaint together,
perform free-fall gymnastics, tickle each other, and experience additional
interactive events.
The computer combines and alters inputs from separate cameras
trained on each person, each of whom responds in turn to the computer’s
output, playing games in the world created by Videoplace
software. Since participants’ live video images can be manipulated
(moved, scaled, or rotated) in real time, the world that is created is
not bound by the laws of physics. In fact, the result is a virtual reality
in which new laws of cause and effect are created, and can be
changed, from moment to moment. Indeed, the term “virtual reality”
describes the type of experience that can be created with Videoplace
or with the technology invented by Ivan Sutherland.
Virtual realities are part of certain ongoing trends. Most obvious
are the trend from interaction to participation in computer events
and the trend from passive to active art forms. In addition, artificial

868 / Virtual reality
Ivan Sutherland
Ivan Sutherland was born in Hastings, Nebraska, in 1938.
His father was an engineer, and from an early age Sutherland
considered engineering his own destiny, too. He earned a
bachelor’s degree from the Carnegie Institute of Technology in
1959, a master’s degree from the California Institute of Technology
in 1960, and a doctorate from the Massachusetts Institute
of Technology (MIT) in 1963.
His adviser at MIT was Claude Shannon, creator of information
theory, who directed Sutherland to find ways to simplify
the interface between people and computers. Out of this
research came Sketchpad. It was software that allowed people
to draw designs on a computer terminal with a light pen,
an early form of computer-assisted design (CAD). The U.S.
Defense Department’s Advanced Research Projects Center
became interested in Sutherland’s work and hired him to direct
its Information Processing Techniques Office in 1964. In
1966 he left to become an associate professor of electrical engineering
at Harvard University, moving to the University of
Utah in 1968, and then to Caltech in 1975. During his academic
career he developed the graphic interface for virtual
reality, first announced in his ground-breaking 1968 article
“A Head-Mounted Three-Dimensional Display.”
In 1980 Sutherland left academia for industry. He already
had business experience as cofounder of Evans & Sutherland
in Salt Lake City. The new firm, Sutherland, Sproull, and Associates,
which provided consulting services and venture capital,
later became part of Sun Microsystems, Inc. Sutherland remained
as a research fellow and vice president. A member of
the National Academy of Engineering and National Academy
of Sciences, in 1988 Sutherland was awarded the AM Turing
Award, the highest honor in information technology.
experiences are taking on increasing significance. Businesspersons
like to talk about “doing it right the first time.” This can now be
done in many cases, not because fewer mistakes are being made by
people but because those mistakes are being made in simulated environments.
Most important is that virtual realities provide means of express-

ing and experiencing, as well as new ways for people to interact. Entertainment
uses of virtual reality will be as economically significant
as more practical uses, since entertainment is the United States’
number-two export. Vicarious experience through theater, novels,
movies, and television represents a significant percentage of people’s
lives in developed countries. The addition of a radically new
form of physically involving, interactive experience is a major cultural
event that may shape human consciousness as much as earlier
forms of experience have.
Consequences
Most religions offer their believers an escape from this world,
but few technologies have been able to do likewise. Not so with
virtual reality, the fledgling technology in which people explore a
simulated three-dimensional environment generated by a computer.
Using this technology, people can not only escape from this
world but also design the world in which they want to live.
In most virtual reality systems, many of which are still experimental,
one watches the scene, or alternative reality, through threedimensional
goggles in a headset. Sound and tactile sensations enhance
the illusion of reality. Because of the wide variety of actual
and potential applications of virtual reality, from three-dimensional
video games and simulators to remotely operated “telepresence”
systems for the nuclear and undersea industries, interest in the field
is intense.
The term “virtual reality” describes the computer-generated
simulation of reality with physical, tactile, and visual dimensions.
The interactive technology is used by science and engineering researchers
as well as by the entertainment industry, especially in
the form of video games. Virtual reality systems can, for example,
simulate a walk-through of a building in an architectural graphics
program. Virtual reality technology in which the artificial world
overlaps with reality will have major social and psychological implications.
See also Personal computer; Virtual machine.
Virtual reality / 869

870 / Virtual reality
Further Reading
Earnshaw, Rae A., M. A. Gigante, and H. Jones. Virtual Reality Systems.
San Diego: Academic Press, 1993.
Moody, Fred. The Visionary Position: The Inside Story of the Digital
Dreamers Who Are Making Virtual Reality a Reality. New York:
Times Business, 1999.
Sutherland, Ivan Edward. Sketchpad: A Man-Machine Graphical Communication
System. New York: Garland, 1980.

V-2 rocket
V-2 rocket
The invention: The first first long-range, liquid-fueled rocket, the
V-2 was developed by Germany to carry bombs during World
War II.
The people behind the invention:
Wernher von Braun (1912-1977), the chief engineer and prime
motivator of rocket research in Germany during the 1930’s
and 1940’s
Walter Robert Dornberger (1895-1980), the former commander
of the Peenemünde Rocket Research Institute
Ing Fritz Gosslau, the head of the V-1 development team
Paul Schmidt, the designer of the impulse jet motor
The “Buzz Bomb”
871
On May 26, 1943, in the middle of World War II, key German military
officials were briefed by two teams of scientists, one representing
the air force and the other representing the army. Each team had
launched its own experimental aerial war craft. The military chiefs
were to decide which project merited further funding and development.
Each experimental craft had both advantages and disadvantages,
and each counterbalanced the other. Therefore, it was decided
that both craft were to be developed. They were to become the V-1
and the V-2 aircraft.
The impulse jet motor used in the V-1 craft was designed by Munich
engineer Paul Schmidt. On April 30, 1941, the motor had been
used to assist power on a biplane trainer. The development team for
the V-1 was headed by Ing Fritz Gosslau; the aircraft was designed
by Robert Lusser.
The V-1, or “buzz bomb,” was capable of delivering a one-ton warhead
payload. While still in a late developmental stage, it was
launched, under Adolf Hitler’s orders, to terrorize inhabited areas of
London in retaliation for the damage that had been wreaked on Germany
during the war. More than one hundred V-1’s were launched
daily between June 13 and early September, 1944. Because the V-1

872 / V-2 rocket
flew in a straight line and at a constant speed, Allied aircraft were
able to intercept it more easily than they could the V-2.
Two innovative systems made the V-1 unique: the drive operation
and the guidance system. In the motor, oxygen entered the
grid valves through many small flaps. Fuel oil was introduced and
the mixture of fuel and oxygen was ignited. After ignition, the expanded
gases produced the reaction propulsion. When the expanded
gases had vacated, the reduced internal pressure allowed the valve
flaps to reopen, admitting more air for the next cycle.
The guidance system included a small propeller connected to a
revolution counter that was preset based on the distance to the target.
The number of propeller revolutions that it would take to reach
the target was calculated before launch and punched into the counter.
During flight, after the counter had measured off the selected
number of revolutions, the aircraft’s elevator flaps became activated,
causing the craft to dive at the target. Understandably, the accuracy
was not what the engineers had hoped.
Vengeance Weapon 2
According to the Treaty of Versailles (1919), world military forces
were restricted to 100,000 men and a certain level of weaponry. The
German military powers realized very early, however, that the
treaty had neglected to restrict rocket-powered weaponry, which
did not exist at the end of World War I (1914-1918). Wernher von
Braun was hired as chief engineer for developing the V-2 rocket.
The V-2 had a lift-off thrust of 11,550.5 newtons and was propelled
by the combustion of liquid oxygen and alcohol. The propellants
were pumped into the combustion chamber by a steampowered
turboprop. The steam was generated by the decomposition
of hydrogen peroxide, using sodium permanganate as a catalyst.
One innovative feature of the V-2 that is still used was regenerative
cooling, which used alcohol to cool the double-walled
combustion chamber.
The guidance system included two phases: powered and ballistic.
Four seconds after launch, a preprogrammed tilt to 17 degrees
was begun, then acceleration was continued to achieve the desired
trajectory. At the desired velocity, the engine power was cut off via

one of two systems. In the automatic system, a device shut off the
engine at the velocity desired; this method, however, was inaccurate.
The second system sent a radio signal to the rocket’s receiver,
which cut off the power. This was a far more accurate method, but
the extra equipment required at the launch site was an attractive target
for Allied bombers. This system was more often employed toward
the end of the war.
Even the 907-kilogram warhead of the V-2 was a carefully tested
device. The detonators had to be able to withstand 6 g’s of force during
lift-off and reentry, as well as the vibrations inherent in a rocket
flight. Yet they also had to be sensitive enough to ignite the bomb
upon impact and before the explosive became buried in the target
and lost power through diffusion of force.
The V-2’s first successful test was in October of 1942, but it continued
to be developed until August of 1944. During the next eight
months, more than three thousand V-2’s were launched against England
and the Continent, causing immense devastation and living
up to its name: Vergeltungswaffe zwei (vengeance weapon 2). Unfortunately
for Hitler’s regime, the weapon that took fourteen years of
research and testing to perfect entered the war too late to make an
impact upon the outcome.
Impact
V-2 rocket / 873
The V-1 and V-2 had a tremendous impact on the history and development
of space technology. Even during the war, captured V-2’s
were studied by Allied scientists. American rocket scientists were
especially interested in the technology, since they too were working
to develop liquid-fueled rockets.
After the war, German military personnel were sent to the United
States, where they signed contracts to work with the U.S. Army in a
program known as “Operation Paperclip.” Testing of the captured
V-2’s was undertaken at White Sands Missile Range near Alamogordo,
New Mexico. The JB-2 Loon Navy jet-propelled bomb was
developed following the study of the captured German craft.
The Soviet Union also benefited from captured V-2’s and from the
German V-2 factories that were dismantled following the war. With
these resources, the Soviet Union developed its own rocket technol-

874 / V-2 rocket
ogy, which culminated in the launch of Sputnik 1, the world’s first artificial
satellite, on October 4, 1957. The United States was not far behind.
It launched its first satellite, Explorer 1, on January 31, 1958. On
April 12, 1961, the world’s first human space traveler, Soviet cosmonaut
Yuri A. Gagarin, was launched into Earth orbit.
See also Airplane; Cruise missile; Hydrogen bomb; Radar; Rocket;
Stealth aircraft.
Further Reading
Bergaust, Erik. Wernher von Braun: The Authoritative and Definitive
Biographical Profile of the Father of Modern Space Flight. Washington:
National Space Institute, 1976.
De Maeseneer, Guido. Peenemünde: The Extraordinary Story of Hitler’s
Secret Weapons V-1 and V-2. Vancouver: AJ Publishing, 2001.
Piszkiewicz, Dennis. Wernher von Braun: The Man Who Sold the Moon.
Westport, Conn.: Praeger, 1998.

Walkman cassette player
Walkman cassette player
The invention: Inexpensive portable device for listening to stereo
cassettes that was the most successful audio product of the 1980’s
and the forerunner of other portable electronic devices.
The people behind the invention:
Masaru Ibuka (1908-1997), a Japanese engineer who cofounded
Sony
Akio Morita (1921-1999), a Japanese physicist and engineer,
cofounder of Sony
Norio Ohga (1930- ), a Japanese opera singer and
businessman who ran Sony’s tape recorder division before
becoming president of the company in 1982
Convergence of Two Technologies
875
The Sony Walkman was the result of the convergence of two
technologies: the transistor, which enabled miniaturization of electronic
components, and the compact cassette, a worldwide standard
for magnetic recording tape. As the smallest tape player devised,
the Walkman was based on a systems approach that made use of advances
in several unrelated areas, including improved loudspeaker
design and reduced battery size. The Sony company brought them
together in an innovative product that found a mass market in a remarkably
short time.
Tokyo Telecommunications Engineering, which became Sony,
was one of many small entrepreneurial companies that made audio
products in the years following World War II. It was formed in the
ruins of Tokyo, Japan, in 1946, and got its start manufacturing components
for inexpensive radios and record players. They were the
ideal products for a company with some expertise in electrical engineering
and a limited manufacturing capability.
Akio Morita and Masaru Ibuka formed Tokyo Telecommunications
Engineering to make a variety of electrical testing devices and
instruments, but their real interests were in sound, and they decided
to concentrate on audio products. They introduced a reel-to-reel

876 / Walkman cassette player
tape recorder in 1946. Its success ensured that the company would
remain in the audio field. The trade name of the magnetic tape they
manufactured was “Soni,” this was the origin of the company’s new
name, adopted in 1957. The 1953 acquisition of a license to use Bell
Laboratories’ transistor technology was a turning point in the fortunes
of Sony, for it led the company to the highly popular transistor
radio and started it along the path to reducing the size of consumer
products. In the 1960’s, Sony led the way to smaller and cheaper radios,
tape recorders, and television sets, all using transistors instead
of vacuum tubes.
The Consumer Market
The original marketing strategy for manufacturers of mechanical
entertainment devices had been to put one into every home. This
was the goal for Edison’s phonograph, the player piano, the Victrola,
and the radio receiver. Sony and other Japanese manufacturers
found out that if a product were small enough and cheap enough,
two or three might be purchased for home use, or even for outdoor
use. This was the marketing lesson of the transistor radio.
The unparalleled sales of transistor radios indicated that consumer
durables intended for entertainment were not exclusively
used in the home. The appeal of the transistor radio was that it made
entertainment portable. Sony applied this concept to televisions
and tape recorders, developing small portable units powered by
batteries. Sony was first to produce a “personal” television set, with
a five-inch screen. To the surprise of many manufacturers who said
there would never be a market for such a novelty item, it sold well.
It was impossible to reduce tape recorders to the size of transistor
radios because of the problems of handling very small reels of tape
and the high power required to turn them. Portable tape recorders required
several large flashlight batteries. Although tape had the advantage
of recording capability, it could not challenge the popularity
of the microgroove 45 revolution-per-minute (rpm) disc because the
tape player was much more difficult to operate. In the 1960’s, several
types of tape cartridge were introduced to overcome this problem, including
the eight-track tape cartridge and the Philips compact cassette.
Sony and Matsushita were two of the leading Japanese manu-

facturers that quickly incorporated the compact cassette into their
audio products, producing the first cassette players available in the
United States.
The portable cassette players of the 1960’s and 1970’s were based
on the transistor radio concept: small loudspeaker, transistorized
amplifier, and flashlight batteries all enclosed in a plastic case. The
size of transistorized components was being reduced constantly,
and new types of batteries, notably the nickel cadmium combination,
offered higher power output in smaller sizes. The problem of
reducing the size of the loudspeaker without serious deterioration
of sound quality blocked the path to very small cassette players.
Sony’s engineers solved the problem with a very small loudspeaker
device using plastic diaphragms and new, lighter materials for the
magnets. These devices were incorporated into tiny stereo headphones
that set new standards of fidelity.
The first “walkman” was made by Sony engineers for the personal
use of Masaru Ibuka. He wanted to be able to listen to high-fidelity
recorded sound wherever he went, and the tiny player was small
enough to fit inside a pocket. Sony was experienced in reducing the
size of machines. At the same time the walkman was being made up,
Sony engineers were struggling to produce a video recording cassette
that was also small enough to fit into Ibuka’s pocket.
Although the portable stereo was part of a long line of successful
miniaturized consumer products, it was not immediately recognized
as a commercial technology. There were already plenty of cassette
players in home units, in automobiles, and in portable players.
Marketing experts questioned the need for a tiny version. The board
of directors of Sony had to be convinced by Morita that the new
product had commercial potential. The Sony Soundabout portable
cassette player was introduced to the market in 1979.
Impact
Walkman cassette player / 877
The Soundabout was initially treated as a novelty in the audio
equipment industry. At a price of $200, it could not be considered as
a product for the mass market. Although it sold well in Japan, where
people were used to listening to music on headphones, sales in the
United States were not encouraging. Sony’s engineers, working un-

878 / Walkman cassette player
der the direction of Kozo Ohsone, reduced the size and cost of the
machine. In 1981, the Walkman II was introduced. It was 25 percent
smaller than the original version and had 50 percent fewer moving
parts. Its price was considerably lower and continued to fall.
The Walkman opened a huge market for audio equipment that
nobody knew existed. Sony had again confounded the marketing
experts who doubted the appeal of a new consumer electronics
product. It took about two years for Sony’s Japanese competitors,
including Matsushita, Toshiba, and Aiwa, to bring out portable personal
stereos. Such was the popularity of the device that any miniature
cassette player was called a “walkman,” irrespective of the
manufacturer. Sony kept ahead of the competition by constant innovation:
Dolby noise reduction circuits were added in 1982, and a rechargeable
battery feature was introduced in 1985. The machine became
smaller, until it was barely larger than the audio cassette it
played.
Sony developed a whole line of personal stereos. Waterproofed
Walkmans were marketed to customers who wanted musical accompaniment
to water sports. There were special models for tennis
players and joggers. The line grew to encompass about forty different
types of portable cassette players, priced from about $30 to $500
for a high-fidelity model.
In the ten years following the introduction of the Walkman,
Sony sold fifty million units, including twenty-five million in the
United States. Its competitors sold millions more. They were manufactured
all over the Far East and came in a broad range of sizes
and prices, with the cheapest models about $20. Increased competition
in the portable tape player market continually forced down
prices. Sony had to respond to the huge numbers of cheap copies
by redesigning the Walkman to bring down its cost and by automating
its production. The playing mechanism became part of the
integrated circuit that provided amplification, allowing manufacturing
as one unit.
The Walkman did more than revive sales of audio equipment in
the sagging market of the late 1970’s. It stimulated demand for cassette
tapes and helped make the compact cassette the worldwide
standard for magnetic tape. At the time the Walkman was introduced,
the major form of prerecorded sound was the vinyl micro-

Masaru Ibuka
Walkman cassette player / 879
Nicknamed “genius inventor” in college, Masaru Ibuka developed
into a visionary corporate leader and business philosopher.
Born in Nikko City, Japan, in 1908, he took a degree in engineering
from Waseda University in 1933 and went to work
at Photo-Chemical Laboratory, which developed movie film.
Changing to naval research during World War II, he met Akio
Morita, another engineer. After the war they opened an electronics
shop together, calling it the Tokyo Telecommunications
Engineering Corporation, and began experimenting with tape
recorders.
Their first model was a modest success, and the business
grew under Ibuka, who was president and later chairman He
thought up a new, less daunting name for his company, Sony, in
the 1950’s, when it rapidly became a leader in consumer electronics.
His goal was to make existing technology useful to people
in everyday life. “He sowed the seeds of a deep conviction
that our products must bring joy and fun to users,” one of his
successors as president, Nobuyuki Idei, said in 1997.
While American companies were studying military applications
for the newly developed transistor in the 1950’s, Ibuka
and Morita put it to use in an affordable transistor radio and
then found ways to shrink its size and power it with batteries so
that it could be taken anywhere. In a similar fashion, they made
tape recorders and players (such as the Walkman), video players,
compact disc players, and televisions ever cheaper, more reliable,
and more efficiently designed.
A hero in the Japanese business world, Ibuka retired as Sony
chairman in 1976 but continued to help out as a consultant until
his death in 1997.
groove record. In 1983, the ratio of vinyl to cassette sales was 3:2. By
the end of the decade, the audio cassette was the bestselling format
for recorded sound, outselling vinyl records and compact discs
combined by a ratio of 2:1. The compatibility of the audio cassette
used in personal players with the home stereo ensured that it would
be the most popular tape recording medium.
The market for portable personal players in the United States
during the decade of the 1990’s was estimated to be more than

880 / Walkman cassette player
twenty million units each year. Sony accounted for half of the 1991
American market of fifteen million units selling at an average price
of $50. It appeared that there would be more than one in every
home. In some parts of Western Europe, there were more cassette
players than people, reflecting the level of market penetration
achieved by the Walkman.
The ubiquitous Walkman had a noticeable effect on the way
that people listen to music. The sound from the headphones of a
portable player is more intimate and immediate than the sound
coming from the loudspeakers of a home stereo. The listener can
hear a wider range of frequencies and more of the lower amplitudes
of music, while the reverberation caused by sound bouncing
off walls is reduced. The listening public has become accustomed
to the Walkman sound and expects it to be duplicated on
commercial recordings. Recording studios that once mixed their
master recordings to suit the reproduction characteristics of car
or transistor radios began to mix them for Walkman headphones.
Personal stereos also enable the listener to experience more of the
volume of recorded sound because it is injected directly into the
ear.
The Walkman established a market for portable tape players that
exerted an influence on all subsequent audio products. The introduction
of the compact disc (CD) in 1983 marked a completely new
technology of recording based on digital transformation of sound. It
was jointly developed by the Sony and Philips companies. Despite
the enormous technical difficulties of reducing the size of the laser
reader and making it portable, Sony’s engineers devised the Discman
portable compact disc player, which was unveiled in 1984. It
followed the Walkman concept exactly and offered higher fidelity
than the cassette tape version. The Discman sold for about $300
when it was introduced, but its price soon dropped to less than
$100. It did not achieve the volume of sales of the audio cassette version
because fewer CDs than audio cassettes were in use. The slow
acceptance of the compact disc hindered sales growth. The Discman
could not match the portability of the Walkman because vibrations
caused the laser reader to skip tracks.
In the competitive market for consumer electronics products, a
company must innovate to survive. Sony had watched cheap compe-

Walkman cassette player / 881
tition erode the sales of many of its most successful products, particularly
the transistor radio and personal television, and was committed
to both product improvement and new entertainment technologies.
It knew that the personal cassette player had a limited sales potential
in the advanced industrial countries, especially after the introduction
of digital recording in the 1980’s. It therefore sought new technology
to apply to the Walkman concept. Throughout the 1980’s, Sony and
its many competitors searched for a new version of the Walkman.
The next generation of personal players was likely to be based on
digital recording. Sony introduced its digital audio tape (DAT) system
in 1990. This used the same digital technology as the compact
disc but came in tape form. It was incorporated into expensive
home players; naturally, Sony engineered a portable version. The
tiny DAT Walkman offered unsurpassed fidelity of reproduction,
but its incompatibility with any other tape format and its high price
limited its sales to professional musicians and recording engineers.
After the failure of DAT, Sony refocused its digital technology
into a format more similar to the Walkman. Its Mini Disc (MD) used
the same technology as the compact disc but had the advantage of a
recording capability. The 2.5-inch disc was smaller than the CD, and
the player was smaller than the Walkman. The play-only version fit
in the palm of a hand. A special feature prevented the skipping of
tracks that caused problems with the Discman. The Mini Disc followed
the path blazed by the Walkman and represented the most
advanced technology applied to personal stereo players. At a price
of about $500 in 1993, it was still too expensive to compete in the
audio cassette Walkman market, but the history of similar products
illustrates that rapid reduction of price could be achieved even with
a complex technology.
The Walkman had a powerful influence on the development of
other digital and optical technologies. The laser readers of compact
disc players can access visual and textual information in addition to
sound. Sony introduced the Data Discman, a handheld device that
displayed text and pictures on a tiny screen. Several other manufacturers
marketed electronic books. Whatever the shape of future entertainment
and information technologies, the legacy of the Walkman
will put a high premium on portability, small size, and the
interaction of machine and user.

882 / Walkman cassette player
See also Cassette recording; Compact disc; Dolby noise reduction;
Electronic synthesizer; Laser; Transistor; Videocassette recorder.
Further Reading
Bull, Michael. Sounding Out the City: Personal Stereos and the Management
of Everyday Life. New York: Berg, 2000.
Lyons, Nick. The Sony Vision. New York: Crown Publishers, 1976.
Morita, Akio, with Edwin M. Reingold, and Mitsuko Shimomura.
Made in Japan: Akio Morita and Sony. London: HarperCollins, 1994.
Nathan, John. Sony: The Private Life. London: HarperCollins Business,
2001.
Schlender, Brenton R. “How Sony Keeps the Magic Going.” Fortune
125 (February 24, 1992).

Washing machine
Washing machine
The invention: Electrical-powered machines that replaced handoperated
washing tubs and wringers, making the job of washing
clothes much easier.
The people behind the invention:
O. B. Woodrow, a bank clerk who claimed to be the first to
adapt electricity to a remodeled hand-operated washing
machine
Alva J. Fisher (1862-1947), the founder of the Hurley Machine
Company, who designed the Thor electric washing machine,
claiming that it was the first successful electric washer
Howard Snyder, the mechanical genius of the Maytag
Company
Hand Washing
883
Until the development of the electric washing machine in the
twentieth century, washing clothes was a tiring and time-consuming
process. With the development of the washboard, dirt was loosened
by rubbing. Clothes and tubs had to be carried to the water, or the
water had to be carried to the tubs and clothes. After washing and
rinsing, clothes were hand-wrung, hang-dried, and ironed with
heavy, heated irons. In nineteenth century America, the laundering
process became more arduous with the greater use of cotton fabrics.
In addition, the invention of the sewing machine resulted in the mass
production of inexpensive ready-to-wear cotton clothing. With more
clothing, there was more washing.
One solution was hand-operated washing machines. The first
American patent for a hand-operated washing machine was issued
in 1805. By 1857, more than 140 patents had been issued; by 1880, between
4,000 and 5,000 patents had been granted. While most of
these machines were never produced, they show how much the
public wanted to find a mechanical means of washing clothes.
Nearly all the early types prior to the Civil War (1861-1865) were
modeled after the washboard.

884 / Washing machine
Washing machines based upon the rubbing principle had two
limitations: They washed only one item at a time, and the rubbing
was hard on clothes. The major conceptual breakthrough was to
move away from rubbing and to design machines that would clean
by forcing water through a number of clothes at the same time.
An early suction machine used a plunger to force water through
clothes. Later electric machines would have between two and four
suction cups, similar to plungers, attached to arms that went up and
down and rotated on a vertical shaft. Another hand-operated washing
machine was used to rock a tub on a frame back and forth. An
electric motor was later substituted for the hand lever that rocked
the tub. A third hand-operated washing machine was the dolly
type. The dolly, which looked like an upside-down three-legged
milking stool, was attached to the inside of the tub cover and was
turned by a two-handled lever on top of the enclosed tub.
Machine Washing
The hand-operated machines that would later dominate the
market as electric machines were the horizontal rotary cylinder
and the underwater agitator types. In 1851, James King patented
a machine of the first type that utilized two concentric half-full
cylinders. Water in the outer cylinder was heated by a fire beneath
it; a hand crank turned the perforated inner cylinder that
contained clothing and soap. The inner-ribbed design of the rotating
cylinder raised the clothes as the cylinder turned. Once the
clothes reached the top of the cylinder, they dropped back down
into the soapy water.
The first underwater agitator-type machine, the second type,
was patented in 1869. In this machine, four blades at the bottom of
the tub were attached to a central vertical shaft that was turned by
a hand crank on the outside. The agitation created by the blades
washed the clothes by driving water through the fabric. It was not
until 1922, when Howard Snyder of the Maytag Company developed
an underwater agitator with reversible motion, that this type
of machine was able to compete with the other machines. Without
reversible action, clothes would soon wrap around the blades and
not be washed.

Claims for inventing the first electric washing machine came
from O. B. Woodrow, who founded the Automatic Electric Washer
Company, and Alva J. Fisher, who developed the Thor electric
washing machine for the Hurley Machine Corporation. Both Woodrow
and Fisher made their innovations in 1907 by adapting electric
power to modified hand-operated, dolly-type machines. Since only
8 percent of American homes were wired for electricity in 1907, the
early machines were advertised as adaptable to electric or gasoline
power but could be hand-operated if the power source failed. Soon,
electric power was being applied to the rotary cylinder, oscillating,
and suction-type machines. In 1910, a number of companies introduced
washing machines with attached wringers that could be operated
by electricity. The introduction of automatic washers in 1937
meant that washing machines could change phases without the action
of the operator.
Impact
Washing machine / 885
By 1907 (the year electricity was adapted to washing machines),
electric power was already being used to operate fans, ranges, coffee
percolators, flatirons, and sewing machines. By 1920, nearly 35
percent of American residences had been wired for electricity; by
1941, nearly 80 percent had been wired. The majority of American
homes had washing machines by 1941; by 1958, this had risen to an
estimated 90 percent.
The growth of electric appliances, especially washing machines,
is directly related to the decline in the number of domestic servants
in the United States. The development of the electric washing machine
was, in part, a response to a decline in servants, especially
laundresses. Also, rather than easing the work of laundresses with
technology, American families replaced their laundresses with washing
machines.
Commercial laundries were also affected by the growth of electric
washing machines. At the end of the nineteenth century, they
were in every major city and were used widely. Observers noted
that just as spinning, weaving, and baking had once been done in
the home but now were done in commercial establishments, laundry
work had now begun its move out of the home. After World

886 / Washing machine
War II (1939-1945), however, although commercial laundries continued
to grow, their business was centered more and more on institutional
laundry, rather than residential laundry, which they had lost
to the home washing machine.
Some scholars have argued that, on one hand, the return of laundry
to the home resulted from marketing strategies that developed
the image of the American woman as one who is home operating
her appliances. On the other hand, it was probably because the electric
washing machine made the task much easier that American
women, still primarily responsible for the family laundry, were able
to pursue careers outside the home.
See also Electric refrigerator; Microwave cooking; Robot (household);
Vacuum cleaner; Vending machine slug rejector.
Further Reading
Ierley, Merritt. Comforts of Home: The American House and the Evolution
of Modern Convenience. New York: C. Potter, 1999.
“Maytag Heritage Embraces Innovation, Dependable Products.”
Machine Design 71, no. 18 (September, 1999).
Shapiro, Laura. “Household Appliances.” Newsweek 130, no. 24A
(Winter, 1997/1998).

Weather satellite
Weather satellite
The invention: A series of cloud-cover meteorological satellites
that pioneered the reconnaissance of large-scale weather systems
and led to vast improvements in weather forecasting.
The person behind the invention:
Harry Wexler (1911-1962), director of National Weather Bureau
meteorological research
Cameras in Space
887
The first experimental weather satellite, Tiros 1, was launched
from Cape Canaveral on April 1, 1960. Tiros’s orbit was angled to
cover the area from Montreal, Canada, to Santa Cruz, Argentina, in
the Western Hemisphere. Tiros completed an orbit every ninetynine
minutes and, when launched, was expected to survive at least
three months in space, returning thousands of images of large-scale
weather systems.
Tiros 1 was equipped with a pair of vidicon scanner television
cameras, one equipped with a wide-angle lens and the other with a
narrow-angle lens. Both cameras created pictures with five hundred
lines per frame at a shutter speed of 1.5 milliseconds. Each television
camera’s imaging data were stored on magnetic tape for downloading
to ground stations when Tiros 1 was in range. The wideangle
lens provided a low-resolution view of an area covering 2,048
square kilometers. The narrow-angle lens had a resolution of half a
kilometer within a viewing area of 205 square kilometers.
Tiros transmitted its data to ground stations, which displayed
the data on television screens. Photographs of these displays were
then made for permanent records. Tiros weather data were sent to
the Naval Photographic Interpretation Center for detailed meteorological
analysis. Next, the photographs were passed along to the
National Weather Bureau for further study.
Tiros caused some controversy because it was able to image large
areas of the communist world: the Soviet Union, Cuba, and Mongolia.
The weather satellite’s imaging system was not, however, partic-

888 / Weather satellite
Hurricane off the coast of Florida photographed from space. (PhotoDisc)
ularly useful as a spy satellite, and only large-scale surface features
were visible in the images. Nevertheless, the National Aeronautics
and Space Administration (NASA) skirted adverse international reactions
by carefully scrutinizing Tiros’s images for evidence of sensitive
surface features before releasing them publicly.
A Startling Discovery
Tiros 1 was not in orbit very long before it made a significant and
startling discovery. It was the first satellite to document that large
storms have vortex patterns that resemble whirling pinwheels. Within
its lifetime, Tiros photographed more than forty northern mid-latitude
storm systems, and each one had a vortex at its center. These storms
were in various stages of development and were between 800 and
1,600 kilometers in diameter. The storm vortex in most of these was located
inside a 560-kilometer-diameter circle around the center of the
storm’s low-pressure zone. Nevertheless, Tiros’s images did not reveal
at what stage in a storm’s development the vortex pattern formed.

This was typical of Tiros’s data. The satellite was truly an experiment,
and, as is the case with most initial experiments, various new
phenomena were uncovered but were not fully understood. The data
showed clearly that weather systems could be investigated from orbit
and that future weather satellites could be outfitted with sensors that
would lead to better understanding of meteorology on a global scale.
Tiros 1 did suffer from a few difficulties during its lifetime in orbit.
Low contrast in the television imaging system often made it difficult
to distinguish between cloud cover and snow cover. The magnetic
tape system for the high-resolution camera failed at an early
stage. Also, Earth’s magnetic field tended to move Tiros 1 away
from an advantageous Earth observation attitude. Experience with
Tiros 1 led to improvements in later Tiros satellites and many other
weather-related satellites.
Consequences
Weather satellite / 889
Prior to Tiros 1, weather monitoring required networks of groundbased
instrumentation centers, airborne balloons, and instrumented
aircraft. Brief high-altitude rocket flights provided limited coverage
of cloud systems from above. Tiros 1 was the first step in the development
of the permanent monitoring of weather systems. The resulting
early detection and accurate tracking of hurricanes alone have resulted
in savings in both property and human life.
As a result of the Tiros 1 experiment, meteorologists were not
ready to discard ground-based and airborne weather systems in
favor of satellites alone. Such systems could not provide data
about pressure, humidity, and temperature, for example. Tiros 1
did, however, introduce weather satellites as a necessary supplement
to ground-based and airborne systems for large-scale monitoring
of weather systems and storms. Satellites could provide
more reliable and expansive coverage at a far lower cost than a
large contingent of aircraft. Tiros 1, which was followed by nine
similar spacecraft, paved the way for modern weather satellite
systems.
See also Artificial satellite; Communications satellite; Cruise
missile; Radio interferometer; Rocket.

890 / Weather satellite
Further Reading
Fishman, Jack, and Robert Kalish. The Weather Revolution: Innovations
and Imminent Breakthroughs in Accurate Forecasting. New
York: Plenum Press, 1994.
Kahl, Jonathan D. Weather Watch: Forecasting the Weather. Minneapolis,
Minn.: Lerner, 1996.
Rao, Krishna P. Weather Satellites: Systems, Data, and Environmental
Applications. Boston: American Meteorological Society, 1990.
Artist’s depiction of a weather satellite. (PhotoDisc)

Xerography
Xerography
The invention: Process that makes identical copies of documents
with a system of lenses, mirrors, electricity, chemicals that conduct
electricity in bright light, and dry inks (toners) that fuse to
paper by means of heat.
The people behind the invention:
Chester F. Carlson (1906-1968), an American inventor
Otto Kornei (1903- ), a German physicist and engineer
Xerography, Xerography, Everywhere
The term xerography is derived from the Greek for “dry writing.”
The process of xerography was invented by an American, Chester F.
Carlson, who made the first xerographic copy of a document in
1938. Before the development of xerography, the preparation of copies
of documents was often difficult and tedious. Most often, unclear
carbon copies of typed documents were the only available medium
of information transfer.
The development of xerography led to the birth of the giant
Xerox Corporation, and the term xerographic was soon shortened to
Xerox. The process of xerography makes identical copies of a document
by using lens systems, mirrors, electricity, chemicals that conduct
electricity in bright light (“semiconductors”), and dry inks
called “toners” that are fused to copy paper by means of heat. The
process makes it easy to produce identical copies of a document
quickly and cheaply. In addition, xerography has led to huge advances
in information transfer, the increased use of written documents,
and rapid decision-making in all areas of society. Xeroxing
can produce both color and black-and-white copies.
From the First Xerox Copy to Modern Photocopies
891
On October 22, 1938, after years of effort, Chester F. Carlson produced
the first Xerox copy. Reportedly, his efforts grew out of his
1930’s job in the patent department of the New York firm P. R.

892 / Xerography
Mallory and Company. He was looking for a quick, inexpensive
method for making copies of patent diagrams and other patent
specifications. Much of Carlson’s original work was conducted in
the kitchen of his New York City apartment or in a room behind a
beauty parlor in Astoria, Long Island. It was in Astoria that Carlson,
with the help of Otto Kornei, produced the first Xerox copy (of the
inscription “10-22-38 Astoria”) on waxed paper.
The first practical method of xerography used the element selenium,
a substance that conducts electricity only when it is exposed
to light. The prototype Xerox copying machines were developed as
a result of the often frustrating, nerve-wracking, fifteen-year collaboration
of Carlson, scientists and engineers at the Battelle Memorial
Institute in Columbus, Ohio, and the Haloid Company of Rochester,
New York. The Haloid Company financed the effort after 1947,
based on an evaluation made by an executive, John H. Dessauer. In
return, the company obtained the right to manufacture and market
Xerox machines. The company, which was originally a manufacturer
of photographic paper, evolved into the giant Xerox Corporation.
Carlson became very wealthy as a result of the royalties and
dividends paid to him by the company.
Early xerographic machines operated in several stages. First, the
document to be copied was positioned above a mirror so that its image,
lit by a flash lamp and projected by a lens, was reflected onto a
drum coated with electrically charged selenium. Wherever dark
sections of the document’s image were reflected, the selenium coating
retained its positive charge. Where the image was light, the
charge of the selenium was lost, because of the photoactive properties
of the selenium.
Next, the drum was dusted with a thin layer of a negatively
charged black powder called a “toner.” Toner particles stuck to positively
charged dark areas of the drum and produced a visible image
on the drum. Then, Xerox copy paper, itself positively charged, was
put in contact with the drum, where it picked up negatively charged
toner. Finally, an infrared lamp heated the paper and the toner, fusing
the toner to the paper and completing the copying process.
In ensuing years, the Xerox Corporation engineered many changes
in the materials and mechanics of Xerox copiers. For example, the
semiconductors and toners were changed, which increased both the

Chester F. Carlson
Xerography / 893
The copying machine changed Chester Floyd Carlson’s life
even before he invented it. While he was experimenting with
photochemicals in his apartment, the building owner’s daughter
came by to complain about the stench Carlson was creating.
However, she found Carlson himself more compelling than her
complaints and married him not long afterward. Soon Carlson
transferred his laboratory to a room behind his mother-in-law’s
beauty parlor, where he devoted ten dollars a month from his
meager wages to spend on research.
Born in Seattle, Washington, in 1906, Carlson learned early
to husband his resources, set his goals high, and never give up.
Both his father and mother were sickly, and so after he was fourteen,
Carlson was the family’s main breadwinner. His relentless
drive and native intelligence got him through high school and
into a community college, where an impressed teacher inspired
him to go even further—into the California Institute of Technology.
After he graduated, he worked for General Electric but lost
his job during the layoffs caused by the Great Depression. In
1933 he hired on with P. R. Mallory Company, an electrical component
manufacturer, which, although not interested in his invention,
at least paid him enough in wages to keep going.
His thirteen-year crusade to invent a copier and then find a
manufacturer to build it ended just as Carlson was nearly
broke. In 1946 Haloid Corporation licensed the rights to Carlson’s
copying machine, but even then the invention did not become
an important part of American communications culture
until the company marketed the Xerox 914 in 1960. The earnings
for Xerox Corporation (as it was called after 1961) leapt
from $33 million to more than $500 million in the next six years,
and Carlson became enormously wealthy. He won the Inventor
of the Year Award in 1964 and the Horatio Alger Award in 1966.
Before he died in 1968, he remembered the hardships of his
youth by donating $100 million to research organizations and
charitable foundations.
quality of copies and the safety of the copying process. In addition,
auxiliary lenses of varying focal length were added, along with other
features, which made it possible to produce enlarged or reduced copies.
Furthermore, modification of the mechanical and chemical prop-

894 / Xerography
erties of the components of the system made it possible to produce
thousands of copies per hour, sort them, and staple them.
The next development was color Xerox copying. Color systems
use the same process steps that the black-and-white systems use,
but the document exposure and toning operations are repeated
three times to yield the three overlaid colored layers (yellow, magenta,
and cyan) that are used to produce multicolored images in
any color printing process. To accomplish this, blue, green, and red
filters are rotated in front of the copier’s lens system. This action
produces three different semiconductor images on three separate
rollers. Next, yellow, magenta, and cyan toners are used—each on
its own roller—to yield three images. Finally, all three images are
transferred to one sheet of paper, which is heated to produce the
multicolored copy. The complex color procedure is slower and
much more expensive than the black-and-white process.
Impact
The quick, inexpensive copying of documents is commonly performed
worldwide. Memoranda that must be distributed to hundreds
of business employees can now be copied in moments, whereas in the
past such a process might have occupied typists for days and cost
hundreds of dollars. Xerox copying also has the advantage that each
copy is an exact replica of the original; no new errors can be introduced,
as was the case when documents had to be retyped. Xerographic
techniques are also used to reproduce X rays and many other
types of medical and scientific data, and the facsimile (fax) machines
that are now used to send documents from one place to another over
telephone lines are a variation of the Xerox process.
All this convenience is not without some problems: The ease of
photocopying has made it possible to reproduce copyrighted publications.
Few students at libraries, for example, think twice about
copying portions of books, since it is easy and inexpensive to do so.
However, doing so can be similar to stealing, according to the law.
With the advent of color photocopying, an even more alarming
problem has arisen: Thieves are now able to use this technology to
create counterfeit money and checks. Researchers will soon find a
way to make such important documents impossible to copy.

See also Fax machine; Instant photography; Laser-diode recording
process.
Further Reading
Xerography / 895
Kelley, Neil D. “Xerography: The Greeks Had a Word for It.”
Infosystems 24, no. 1 (January, 1977).
McClain, Dylan L. “Duplicate Efforts.” New York Times (November
30, 1998).
Mort, J. The Anatomy of Xerography: Its Invention and Evolution. Jefferson,
N.C.: McFarland, 1989.

896
X-ray crystallography
X-ray crystallography
The invention: Technique for using X rays to determine the crystal
structures of many substances.
The people behind the invention:
Sir William Lawrence Bragg (1890-1971), the son of Sir William
Henry Bragg and cowinner of the 1915 Nobel Prize in Physics
Sir William Henry Bragg (1862-1942), an English mathematician
and physicist and cowinner of the 1915 Nobel Prize in
Physics
Max von Laue (1879-1960), a German physicist who won the
1914 Nobel Prize in Physics
Wilhelm Conrad Röntgen (1845-1923), a German physicist who
won the 1901 Nobel Prize in Physics
René-Just Haüy (1743-1822), a French mathematician and
mineralogist
Auguste Bravais (1811-1863), a French physicist
The Elusive Crystal
A crystal is a body that is formed once a chemical substance has
solidified. It is uniformly shaped, with angles and flat surfaces that
form a network based on the internal structure of the crystal’s atoms.
Determining what these internal crystal structures look like is
the goal of the science of X-ray crystallography. To do this, it studies
the precise arrangements into which the atoms are assembled.
Central to this study is the principle of X-ray diffraction. This
technique involves the deliberate scattering of X rays as they are
shot through a crystal, an act that interferes with their normal path
of movement. The way in which the atoms are spaced and arranged
in the crystal determines how these X rays are reflected off them
while passing through the material. The light waves thus reflected
form a telltale interference pattern. By studying this pattern, scientists
can discover variations in the crystal structure.
The development of X-ray crystallography in the early twentieth
century helped to answer two major scientific questions: What are X

ays? and What are crystals? It gave birth to a new technology for
the identification and classification of crystalline substances.
From studies of large, natural crystals, chemists and geologists
had established the elements of symmetry through which one
could classify, describe, and distinguish various crystal shapes.
René-Just Haüy, about a century before, had demonstrated that diverse
shapes of crystals could be produced by the repetitive stacking
of tiny solid cubes.
Auguste Bravais later showed, through mathematics, that all
crystal forms could be built from a repetitive stacking of three-dimensional
arrangements of points (lattice points) into “space lattices,”
but no one had ever been able to prove that matter really was
arranged in space lattices. Scientists did not know if the tiny building
blocks modeled by space lattices actually were solid matter
throughout, like Haüy’s cubes, or if they were mostly empty space,
with solid matter located only at the lattice points described by
Bravais.
With the disclosure of the atomic model of Danish physicist Niels
Bohr in 1913, determining the nature of the building blocks of crystals
took on a special importance. If crystal structure could be
shown to consist of atoms at lattice points, then the Bohr model
would be supported, and science then could abandon the theory
that matter was totally solid.
X Rays Explain Crystal Structure
X-ray crystallography / 897
In 1912, Max von Laue first used X rays to study crystalline matter.
Laue had the idea that irradiating a crystal with X rays might
cause diffraction. He tested this idea and found that X rays were
scattered by the crystals in various directions, revealing on a photographic
plate a pattern of spots that depended on the orientation
and the symmetry of the crystal.
The experiment confirmed in one stroke that crystals were not
solid and that their matter consisted of atoms occupying lattice sites
with substantial space in between. Further, the atomic arrangements
of crystals could serve to diffract light rays. Laue received the 1914
Nobel Prize in Physics for his discovery of the diffraction of X rays in
crystals.

(Library of Congess)
898 / X-ray crystallography
Sir William Henry Bragg
and Sir William Lawrence Bragg
William Henry Bragg, senior member of one of the most illustrious
father-son scientific teams in history, was born in Cumberland,
England, in 1862. Talented at mathematics, he
studied that field at Trinity College, Cambridge, and
physics at the Cavendish Laboratory, then moved into
a professorship at the University of Adelaide in
Australia. Despite an underequipped laboratory, he
proved that the atom is not a solid body, and his
work with X rays attracted the attention of Ernest
Rutherford in England, who helped him win a professorship
at the University of Leeds in 1908.
By then his eldest son, William Lawrence Bragg,
William Henry Bragg
was showing considerable scientific abilities of his
own. Born in Adelaide in 1890, he also attended Trinity
College, Cambridge, and performed research at the Cavendish.
It was while there that father and son worked together to
establish the specialty of X-ray crystallography. When they
shared the 1915 Nobel Prize in Physics for their work, the son
was only twenty-five years old—the youngest person ever to
receive a Nobel Prize in any field.
The younger Bragg was also an artillery officer in France
during World War I. Meanwhile, his father worked for the
Royal Admiralty. The hydrophone he invented to detect submarines
underwater earned him a knighthood in 1920. The father
moved to University College, London, and became director
of the Royal Institution. His popular lectures about the latest
scientific developments made him famous among the public,
while his elevation to president of the Royal Society in 1935
placed him among the most influential scientists in the world.
He died in 1942.
The son taught at the University of Manchester in 1919 and
then in 1938 became director of the National Physics Laboratory
and professor of physics at the Cavendish. Following the
father’s example, he became an administrator and professor at
the Royal Institution, where he also distinguished himself with
his popular lectures. He encouraged research using X-ray crystallography,
including the work that unlocked the structure of
deoxyribonucleic acid (DNA). Knighted in 1941, he became a
royal Companion of Honor in 1967. He died in 1971.

Still, the diffraction of X rays was not yet a proved scientific fact.
Sir William Henry Bragg contributed the final proof by passing one of
the diffracted beams through a gas and achieving ionization of the
gas, the same effect that true X rays would have caused. He also used
the spectrometer he built for this purpose to detect and measure specific
wavelengths of X rays and to note which orientations of crystals
produced the strongest reflections. He noted that X rays, like visible
light, occupy a definite part of the electromagnetic spectrum. Yet
most of Bragg’s work focused on actually using X rays to deduce
crystal structures.
Sir Lawrence Bragg was also deeply interested in this new phenomenon.
In 1912, he had the idea that the pattern of spots was an indication
that the X rays were being reflected from the planes of atoms in the crystal.
If that were true, Laue pictures could be used to obtain information
about the structures of crystals. Bragg developed an equation that described
the angles at which X rays would be most effectively diffracted
by a crystal. This was the start of the X-ray analysis of crystals.
Henry Bragg had at first used his spectrometer to try to determine
whether X rays had a particulate nature. It soon became evident,
however, that the device was a far more powerful way of analyzing
crystals than the Laue photograph method had been. Not
long afterward, father and son joined forces and founded the new
science of X-ray crystallography. By experimenting with this technique,
Lawrence Bragg came to believe that if the lattice models of
Bravais applied to actual crystals, a crystal structure could be
viewed as being composed of atoms arranged in a pattern consisting
of a few sets of flat, regularly spaced, parallel planes.
Diffraction became the means by which the Braggs deduced the
detailed structures of many crystals. Based on these findings, they
built three-dimensional scale models out of wire and spheres that
made it possible for the nature of crystal structures to be visualized
clearly even by nonscientists. Their results were published in the
book X-Rays and Crystal Structure (1915).
Impact
X-ray crystallography / 899
The Braggs founded an entirely new discipline, X-ray crystallography,
which continues to grow in scope and application. Of partic-

900 / X-ray crystallography
ular importance was the early discovery that atoms, rather than
molecules, determine the nature of crystals. X-ray spectrometers of
the type developed by the Braggs were used by other scientists to
gain insights into the nature of the atom, particularly the innermost
electron shells. The tool made possible the timely validation of some
of Bohr’s major concepts about the atom.
X-ray diffraction became a cornerstone of the science of mineralogy.
The Braggs, chemists such as Linus Pauling, and a number of
mineralogists used the tool to do pioneering work in deducing the
structures of all major mineral groups. X-ray diffraction became the
definitive method of identifying crystalline materials.
Metallurgy progressed from a technology to a science as metallurgists
became able, for the first time, to deduce the structural order of
various alloys at the atomic level. Diffracted X rays were applied in
the field of biology, particularly at the Cavendish Laboratory under
the direction of Lawrence Bragg. The tool proved to be essential for
deducing the structures of hemoglobin, proteins, viruses, and eventually
the double-helix structure of deoxyribonucleic acid (DNA).
See also Field ion microscope; Geiger counter; Holography;
Mass spectrograph; Neutrino detector; Scanning tunneling microscope;
Thermal cracking process; Ultramicroscope.
Further Reading
Achilladelis, Basil, and Mary Ellen Bowden. Structures of Life. Philadelphia:
The Center, 1989.
Bragg, William Lawrence. The Development of X-Ray Analysis. New
York: Hafner Press, 1975.
Thomas, John Meurig. “Architecture of the Invisible.” Nature 364
(August 5, 1993).

X-ray image intensifier
X-ray image intensifier
The invention: A complex electronic device that increases the intensity
of the light in X-ray beams exiting patients, thereby making
it possible to read finer details.
The people behind the invention:
Wilhelm Conrad Röntgen (1845-1923), a German physicist
Thomas Alva Edison (1847-1931), an American inventor
W. Edward Chamberlain, an American physician
Thomson Electron Tubes, a French company
Radiologists Need Dark Adaptation
901
Thomas Alva Edison invented the fluoroscope in 1896, only one
year after Wilhelm Conrad Röntgen’s discovery of X rays. The primary
function of the fluoroscope is to create images of the internal
structures and fluids in the human body. During fluoroscopy, the radiologist
who performs the procedure views a continuous image of
the motion of the internal structures.
Although much progress was made during the first half of the
twentieth century in recording X-ray images on plates and film,
fluoroscopy lagged behind. In conventional fluoroscopy, a radiologist
observed an image on a dim fluoroscopic screen. In the same
way that it is more difficult to read a telephone book in dim illumination
than in bright light, it is much harder to interpret a dim
fluoroscopic image than a bright one. In the early years of fluoroscopy,
the radiologist’s eyes had to be accustomed to dim illumination
for at least fifteen minutes before performing fluoroscopy.
“Dark adaptation” was the process of wearing red goggles under
normal illumination so that the amount of light entering the eye
was reduced.
The human retina contains two kinds of light-sensitive elements:
rods and cones. The dim light emitted by the screen of the
fluoroscope, even under the best conditions, required the radiologist
to see only with the rods, and vision is much less accurate in
such circumstances. For normal rod-and-cone vision, the bright-

902 / X-ray image intensifier
ness of the screen might have to be increased a thousandfold.
Such an increase was impossible; even if an X-ray tube could have
been built that was capable of emitting a beam of sufficient intensity,
its rays would have been fatal to the patient in less than a
minute.
Fluoroscopy in an Undarkened Room
In a classic paper delivered at the December, 1941, meeting of
the Radiological Society of North America, Dr. W. Edward Chamberlain
of Temple University Medical School proposed applying to
fluoroscopy the techniques of image amplification (also known as
image intensification) that had already been adapted for use in the
electron microscope and in television. The idea was not original
with him. Four or five years earlier, Irving Langmuir of General
Electric Company had applied for a patent for a device that would
intensify a fluoroscopic image. “It is a little hard to understand the
delay in the creation of a practical device,” Chamberlain noted.
“Perhaps what is needed is a realization by the physicists and the
engineers of the great need for brighter fluoroscopic images and
the great advantage to humanity which their arrival would entail.”
Chamberlain’s brilliant analysis provided precisely that awareness.
World War II delayed the introduction of fluoroscopic image
intensification, but during the 1950’s, a number of image intensifiers
based on the principles Chamberlain had outlined came on the
market.
The image-intensifier tube is a complex electronic device that receives
the X-ray beam exiting the patient, converts it into light, and
increases the intensity of that light. The tube is usually contained in
a glass envelope that provides some structural support and maintains
a vacuum. The X rays, after passing through the patient, impinge
on the face of a screen and trigger the ejection of electrons,
which are then speeded up and focused within the tube by means of
electrical fields. When the speeded-up electrons strike the phosphor
at the output end of the tube, they trigger the emission of light photons
that re-create the desired image, which is several thousand
times brighter than is the case with the conventional fluoroscopic
screen. The output of the image intensifier can be viewed in an

undarkened room without prior dark adaptation, thus saving the
radiologist much valuable time.
Moving pictures can be taken of the output phosphor of the intensifying
tube or of the television receiver image, and they can be
stored on motion picture film or on magnetic tape. This permanently
records the changing image and makes it possible to reduce
further the dose of radiation that a patient must receive. Instead of
prolonging the radiation exposure while examining various parts of
the image or checking for various factors, the radiologist can record
a relatively short exposure and then rerun the motion picture film or
tape as often as necessary to analyze the information that it contains.
The radiation dosage that is administered to the patient can be
reduced to a tenth or even a hundredth of what it had been previously,
and the same amount of diagnostic information or more can
be obtained. The radiation dose that the radiologist receives is reduced
to zero or almost zero. In addition, the combination of the
brighter image and the lower radiation dosage administered to the
patient has made it possible for radiologists to develop a number of
important new diagnostic procedures that could not have been accomplished
at all without image intensification.
Impact
X-ray image intensifier / 903
The image intensifier that was developed by the French company
Thomson Electron Tubes in 1959 had an input-phosphor diameter,
or field, of four inches. Later on, image intensifiers with
field sizes of up to twenty-two inches became available, making it
possible to create images of much larger portions of the human
anatomy.
The most important contribution made by image intensifiers was
to increase fluoroscopic screen illumination to the level required for
cone vision. These devices have made dark adaptation a thing of the
past. They have also brought the television camera into the fluoroscopic
room and opened up a whole new world of fluoroscopy.
See also Amniocentesis; CAT scanner; Electrocardiogram; Electroencephalogram;
Mammography; Nuclear magnetic resonance;
Ultrasound.

904 / X-ray image intensifier
Further Reading
Glasser, Otto. Dr. W. C. Röntgen. 2d ed. Springfield, Ill.: Charles C.
Thomas, 1972.
Isherwood, Ian, Adrian Thomas, and Peter Neil Temple Wells. The
Invisible Light: One Hundred Years of Medical Radiology. Cambridge,
Mass.: Blackwell Science, 1995.
Lewis, Ricki. “Radiation Continuing Concern with Fluoroscopy.”
FDA Consumer 27 (November, 1993).

Yellow fever vaccine
Yellow fever vaccine
The invention: The first safe vaccine agaisnt the virulent yellow fever
virus, which caused some of the deadliest epidemics of the
nineteenth and early twentieth centuries.
The people behind the invention:
Max Theiler (1899-1972), a South African microbiologist
Wilbur Augustus Sawyer (1879-1951), an American physician
Hugh Smith (1902-1995), an American physician
A Yellow Flag
905
Yellow fever, caused by a virus and transmitted by mosquitoes,
infects humans and monkeys. After the bite of the infecting mosquito,
it takes several days before symptoms appear. The onset of
symptoms is abrupt, with headache, nausea, and vomiting. Because
the virus destroys liver cells, yellowing of the skin and eyes is common.
Approximately 10 to 15 percent of patients die after exhibiting
terrifying signs and symptoms. Death occurs usually from liver necrosis
(decay) and liver shutdown. Those that survive recover completely
and are immunized.
At the beginning of the twentieth century, there was no cure for
yellow fever. The best that medical authorities could do was to quarantine
the afflicted. Those quarantines usually waved the warning yellow
flag, which gave the disease its colloquial name, “yellow jack.”
After the Aëdes aegypti mosquito was clearly identified as the carrier
of the disease in 1900, efforts were made to combat the disease
by wiping out the mosquito. Most famous in these efforts were the
American army surgeon Walter Reed and the Cuban physician
Carlos J. Finlay. This strategy was successful in Panama and Cuba
and made possible the construction of the Panama Canal. Still, the
yellow fever virus persisted in the tropics, and the opening of the
Panama Canal increased the danger of its spreading aboard the
ships using this new route.
Moreover, the disease, which was thought to be limited to the
jungles of South and Central America, had begun to spread arounds

906 / Yellow fever vaccine
the world to wherever the mosquito Aëdes aegypti could carry the
virus. Mosquito larvae traveled well in casks of water aboard
trading vessels and spread the disease to North America and Europe.
Immunization by Mutation
Max Theiler received his medical education in London. Following
that, he completed a four-month course at the London School of
Hygiene and Tropical Medicine, after which he was invited to come
to the United States to work in the department of tropical medicine
at Harvard University.
While there, Theiler started working to identify the yellow fever
organism. The first problem he faced was finding a suitable
laboratory animal that could be infected with yellow fever. Until
that time, the only animal successfully infected with yellow fever
was the rhesus monkey, which was expensive and difficult to care
for under laboratory conditions. Theiler succeeded in infecting
laboratory mice with the disease by injecting the virus directly into
their brains.
Laboratory work for investigators and assistants coming in contact
with the yellow fever virus was extremely dangerous. At least
six of the scientists at the Yellow Fever Laboratory at the Rockefeller
Institute died of the disease, and many other workers were
infected. In 1929, Theiler was infected with yellow fever; fortunately,
the attack was so mild that he recovered quickly and resumed
his work.
During one set of experiments, Theiler produced successive generations
of the virus. First, he took virus from a monkey that had died
of yellow fever and used it to infect a mouse. Next, he extracted the
virus from that mouse and injected it into a second mouse, repeating
the same procedure using a third mouse. All of them died of encephalitis
(inflammation of the brain). The virus from the third mouse was
then used to infect a monkey. Although the monkey showed signs of
yellow fever, it recovered completely. When Theiler passed the virus
through more mice and then into the abdomen of another monkey,
the monkey showed no symptoms of the disease. The results of these
experiments were published by Theiler in the journal Science.

Yellow fever vaccine / 907
This article caught the attention of Wilbur Augustus Sawyer, director
of the Yellow Fever Laboratory at the Rockefeller Foundation
International Health Division in New York. Sawyer, who was working
on a yellow fever vaccine, offered Theiler a job at the Rockefeller
Foundation, which Theiler accepted. Theiler’s mouse-adapted, “attenuated”
virus was given to the laboratory workers, along with human
immune serum, to protect them against the yellow fever virus.
This type of vaccination, however, carried the risk of transferring
other diseases, such as hepatitis, in the human serum.
In 1930, Theiler worked with Eugen Haagen, a German bacteriologist,
at the Rockefeller Foundation. The strategy of the Rockefeller
laboratory was a cautious, slow, and steady effort to culture a strain
of the virus so mild as to be harmless to a human but strong enough
to confer a long-lasting immunity. (To “culture” something—tissue
cells, microorganisms, or other living matter—is to grow it in a specially
prepared medium under laboratory conditions.) They started
with a new strain of yellow fever harvested from a twenty-eightyear-old
West African named Asibi; it was later known as the “Asibi
strain.” It was a highly virulent strain that in four to seven days
killed almost all the monkeys that were infected with it. From time
to time, Theiler or his assistant would test the culture on a monkey
and note the speed with which it died.
It was not until April, 1936, that Hugh Smith, Theiler’s assistant,
called to his attention an odd development as noted in the laboratory
records of strain 17D. In its 176th culture, 17D had failed to kill
the test mice. Some had been paralyzed, but even these eventually
recovered. Two monkeys who had received a dose of 17D in their
brains survived a mild attack of encephalitis, but those who had
taken the infection in the abdomen showed no ill effects whatever.
Oddly, subsequent subcultures of the strain killed monkeys and
mice at the usual rate. The only explanation possible was that a mutation
had occurred unnoticed.
The batch of strain 17D was tried over and over again on monkeys
with no harmful effects. Instead, the animals were immunized
effectively. Then it was tried on the laboratory staff, including
Theiler and his wife, Lillian. The batch injected into humans had the
same immunizing effect. Neither Theiler nor anyone else could explain
how the mutation of the virus had resulted. Attempts to dupli-

908 / Yellow fever vaccine
cate the experiment, using the same Asibi virus, failed. Still, this was
the first safe vaccine for yellow fever. In June, 1937, Theiler reported
this crucial finding in the Journal of Experimental Medicine.
Impact
Following the discovery of the vaccine, Theiler’s laboratory became
a production plant for the 17D virus. Before World War II
(1939-1945), more than one million vaccination doses were sent to
Brazil and other South American countries. After the United States
entered the war, eight million soldiers were given the vaccine before
being shipped to tropical war zones. In all, approximately fifty million
people were vaccinated in the war years.
Yet although the vaccine, combined with effective mosquito control,
eradicated the disease from urban centers, yellow fever is still
present in large regions of South and Central America and of Africa.
The most severe outbreak of yellow fever ever known occurred
from 1960 to 1962 in Ethiopia; out of one hundred thousand people
infected, thirty thousand died.
The 17D yellow fever vaccine prepared by Theiler in 1937 continues
to be the only vaccine used by the World Health Organization,
more than fifty years after its discovery. There is a continuous effort
by that organization to prevent infection by immunizing the people
living in tropical zones.
See also Antibacterial drugs; Penicillin; Polio vaccine (Sabin); Polio
vaccine (Salk); Salvarsan; Tuberculosis vaccine; Typhus vaccine.
Further Reading
DeJauregui, Ruth. One Hundred Medical Milestones That Shaped World
History. San Mateo, Calif.: Bluewood Books, 1998.
Delaporte, François. The History of Yellow Fever: An Essay on the Birth
of Tropical Medicine. Cambridge, Mass.: MIT Press, 1991.
Theiler, Max, and Wilbur G. Downs. The Arthropod-borne Viruses of
Vertebrates: An Account of the Rockefeller Foundation Virus Program,
1951-1970. New Haven, Conn.: Yale University Press, 1973.
Williams, Greer. Virus Hunters. London: Hutchinson, 1960.

Time Line
Time Line
Date Invention
c. 1900 Electrocardiogram
1900 Brownie camera
1900 Dirigible
1901 Artificial insemination
1901 Vat dye
1901-1904 Silicones
1902 Ultramicroscope
1903 Airplane
1903 Disposable razor
1903-1909 Laminated glass
1904 Alkaline storage battery
1904 Photoelectric cell
1904 Vacuum tube
1905 Blood transfusion
1905-1907 Plastic
1906 Gyrocompass
1906 Radio
1906-1911 Tungsten filament
1907 Autochrome plate
1908 Ammonia
1908 Geiger counter
1908 Interchangeable parts
1908 Oil-well drill bit
1908 Vacuum cleaner
1910 Radio crystal sets
1910 Salvarsan
1910 Washing machine
1910-1939 Electric refrigerator
1912 Color film
1912 Diesel locomotive
1912-1913 Solar thermal engine
1912-1914 Artificial kidney
1912-1915 X-ray crystallography
909

910 / Time Line
Date Invention
1913 Assembly line
1913 Geothermal power
1913 Mammography
1913 Thermal cracking process
1915 Long-distance telephone
1915 Propeller-coordinated machine gun
1915 Pyrex glass
1915 Long-distance radiotelephony
1916-1922 Internal combustion engine
1917 Food freezing
1917 Sonar
1919 Mass spectrograph
1921 Tuberculosis vaccine
1923 Rotary dial telephone
1923 Television
1923 and 1951 Syphilis test
1924 Ultracentrifuge
1925-1930 Differential analyzer
1926 Buna rubber
1926 Rocket
1926 Talking motion pictures
1927 Heat pump
1928 Pap test
1929 Electric clock
1929 Electroencephalogram
1929 Iron lung
1930’s Contact lenses
1930’s Vending machine slug rejector
1930 Refrigerant gas
1930 Typhus vaccine
1930-1935 FM Radio
1931 Cyclotron
1931 Electron microscope
1931 Neoprene
1932 Fuel cell
1932-1935 Antibacterial drugs

Date Invention
1933-1954 Freeze-drying
1934 Bathysphere
1935 Nylon
1935 Radar
1935 Richter scale
1936 Fluorescent lighting
1937 Yellow fever vaccine
1938 Polystyrene
1938 Teflon
1938 Xerography
1940’s Carbon dating
1940 Color television
1940 Penicillin
1940-1955 Microwave cooking
1941 Polyester
1941 Touch-tone telephone
1941 Turbojet
1942 Infrared photography
1942-1950 Orlon
1943 Aqualung
1943 Colossus computer
1943 Nuclear reactor
1943-1946 ENIAC computer
1944 Mark I calculator
1944 V-2 rocket
1945 Atomic bomb
1945 Tupperware
1946 Cloud seeding
1946 Synchrocyclotron
1947 Holography
1948 Atomic clock
1948 Broadcaster guitar
1948 Instant photography
1948-1960 Bathyscaphe
1949 BINAC computer
1949 Community antenna television
Time Line / 911

912 / Time Line
Date Invention
1950 Cyclamate
1950-1964 In vitro plant culture
1951 Breeder reactor
1951 UNIVAC computer
1951-1952 Hydrogen bomb
1952 Amniocentesis
1952 Hearing aid
1952 Polio vaccine (Salk)
1952 Reserpine
1952 Steelmaking process
1952-1956 Field ion microscope
1953 Artificial hormone
1953 Heart-lung machine
1953 Polyethylene
1953 Synthetic amino acid
1953 Transistor
1953-1959 Hovercraft
mid-1950’s Synthetic RNA
1954 Photovoltaic cell
1955 Radio interferometer
1955-1957 FORTRAN programming language
1956 Birth control pill
1957 Artificial satellite
1957 Nuclear power plant
1957 Polio vaccine (Sabin)
1957 Transistor radio
1957 Velcro
1957-1972 Pacemaker
1958 Ultrasound
1959 Atomic-powered ship
1959 COBOL computer language
1959 IBM Model 1401 computer
1959 X-ray image intensifier
1960’s Rice and wheat strains
1960’s Virtual machine
1960 Laser

Date Invention
Time Line / 913
1960 Memory metal
1960 Telephone switching
1960 Weather satellite
1961 SAINT
1962 Communications satellite
1962 Laser eye surgery
1962 Robot (industrial)
1963 Cassette recording
1964 Bullet train
1964 Electronic synthesizer
1964-1965 BASIC programming language
1966 Tidal power plant
1967 Coronary artery bypass surgery
1967 Dolby noise reduction
1967 Neutrino detector
1967 Synthetic DNA
1969 Bubble memory
1969 The Internet
1969-1983 Optical disk
1970 Floppy disk
1970 Videocassette recorder
1970-1980 Virtual reality
1972 CAT scanner
1972 Pocket calculator
1975-1979 Laser-diode recording process
1975-1990 Fax machine
1976 Supercomputer
1976 Supersonic passenger plane
1976-1988 Stealth aircraft
1977 Apple II computer
1977 Fiber-optics
1977-1985 Cruise missile
1978 Cell phone
1978 Compressed-air-accumulating power plant
1978 Nuclear magnetic resonance
1978-1981 Scanning tunneling microscope

914 / Time Line
Date Invention
1979 Artificial blood
1979 Walkman cassette player
1980’s CAD/CAM
1981 Personal computer
1982 Abortion pill
1982 Artificial heart
1982 Genetically engineered insulin
1982 Robot (household)
1983 Artificial chromosome
1983 Aspartame
1983 Compact disc
1983 Hard disk
1983 Laser vaporization
1985 Genetic “fingerprinting”
1985 Tevatron accelerator
1997 Cloning
2000 Gas-electric car

Topics by Category
Topics by Category
Agriculture
Artificial insemination
Cloning
Cloud seeding
In vitro plant culture
Rice and wheat strains
Astronomy
Artificial satellite
Communications satellite
Neutrino detector
Radio interferometer
Weather satellite
Aviation and space
Airplane
Artificial satellite
Communications satellite
Dirigible
Radio interferometer
Rocket
Stealth aircraft
Turbojet
V-2 rocket
Weather satellite
Biology
Artificial chromosome
Artificial insemination
Cloning
Genetic “fingerprinting”
In vitro plant culture
Synthetic amino acid
Synthetic DNA
Synthetic RNA
Ultracentrifuge
Chemistry
Ammonia
Fuel cell
Refrigerant gas
Silicones
Thermal cracking process
Ultracentrifuge
Ultramicroscope
Vat dye
X-ray crystallography
Communications
915
Cassette recording
Cell phone
Color television
Communications satellite
Community antenna television
Dolby noise reduction
Electronic synthesizer
Fax machine
Fiber-optics
FM radio
Hearing aid
Laser-diode recording process
Long-distance radiotelephony
Long-distance telephone

916 / Topics by Category
Radar
Radio
Radio crystal sets
Rotary dial telephone
Sonar
Talking motion pictures
Telephone switching
Television
Touch-tone telephone
Transistor radio
Vacuum tube
Videocassette recorder
Xerography
Computer science
Apple II computer
BASIC programming language
BINAC computer
Bubble memory
COBOL computer language
Colossus computer
Computer chips
Differential analyzer
ENIAC computer
Floppy disk
FORTRAN programming
language
Hard disk
IBM Model 1401 computer
Internet
Mark I calculator
Optical disk
Personal computer
Pocket calculator
SAINT
Supercomputer
UNIVAC computer
Virtual machine
Virtual reality
Consumer products
Apple II computer
Aspartame
Birth control pill
Broadcaster guitar
Brownie camera
Cassette recording
Cell phone
Color film
Color television
Compact disc
Cyclamate
Disposable razor
Electric refrigerator
FM radio
Gas-electric car
Hearing aid
Instant photography
Internet
Nylon
Orlon
Personal computer
Pocket calculator
Polyester
Pyrex glass
Radio
Rotary dial telephone
Teflon
Television
Touch-tone telephone
Transistor radio
Tupperware
Vacuum cleaner
Velcro

Videocassette recorder
Walkman cassette player
Washing machine
Drugs and vaccines
Abortion pill
Antibacterial drugs
Artificial hormone
Birth control pill
Genetically engineered insulin
Penicillin
Polio vaccine (Sabin)
Polio vaccine (Salk)
Reserpine
Salvarsan
Tuberculosis vaccine
Typhus vaccine
Yellow fever vaccine
Earth science
Aqualung
Bathyscaphe
Bathysphere
Cloud seeding
Richter scale
X-ray crystallography
Electronics
Cassette recording
Cell phone
Color television
Communications satellite
Compact disc
Dolby noise reduction
Electronic synthesizer
Fax machine
Fiber-optics
FM radio
Hearing aid
Laser-diode recording process
Long-distance radiotelephony
Long-distance telephone
Radar
Radio
Radio crystal sets
Rotary dial telephone
Sonar
Telephone switching
Television
Touch-tone telephone
Transistor
Transistor radio
Vacuum tube
Videocassette recorder
Walkman cassette player
Xerography
Energy
Topics by Category / 917
Alkaline storage battery
Breeder reactor
Compressed-air-accumulating
power plant
Fluorescent lighting
Fuel cell
Gas-electric car
Geothermal power
Heat pump
Nuclear power plant
Nuclear reactor
Oil-well drill bit
Photoelectric cell
Photovoltaic cell

918 / Topics by Category
Solar thermal engine
Tidal power plant
Vacuum tube
Engineering
Airplane
Assembly line
Bullet train
CAD/CAM
Differential analyzer
Dirigible
ENIAC computer
Gas-electric car
Internal combustion engine
Oil-well drill bit
Robot (household)
Robot (industrial)
Steelmaking process
Tidal power plant
Vacuum cleaner
Washing machine
Exploration
Carbon dating
Aqualung
Bathyscaphe
Bathysphere
Neutrino detector
Radar
Radio interferometer
Sonar
Food science
Aspartame
Cyclamate
Electric refrigerator
Food freezing
Freeze-drying
Genetically engineered insulin
In vitro plant culture
Microwave cooking
Polystyrene
Refrigerant gas
Rice and wheat strains
Teflon
Tupperware
Genetic engineering
Amniocentesis
Artificial chromosome
Artificial insemination
Cloning
Genetic “fingerprinting”
Genetically engineered insulin
In vitro plant culture
Rice and wheat strains
Synthetic amino acid
Synthetic DNA
Synthetic RNA
Home products
Cell phone
Color television
Community antenna television
Disposable razor
Electric refrigerator
Fluorescent lighting
FM radio
Microwave cooking
Radio
Refrigerant gas

Robot (household)
Rotary dial telephone
Television
Touch-tone Telephone
Transistor radio
Tungsten filament
Tupperware
Vacuum cleaner
Videocassette recorder
Washing machine
Manufacturing
Assembly line
CAD/CAM
Interchangeable parts
Memory metal
Polystyrene
Steelmaking process
Materials
Buna rubber
Contact lenses
Disposable razor
Laminated glass
Memory metal
Neoprene
Nylon
Orlon
Plastic
Polyester
Polyethylene
Polystyrene
Pyrex glass
Silicones
Steelmaking process
Teflon
Topics by Category / 919
Tungsten filament
Velcro
Measurement and detection
Amniocentesis
Atomic clock
Carbon dating
CAT scanner
Cyclotron
Electric clock
Electrocardiogram
Electroencephalogram
Electron microscope
Geiger counter
Gyrocompass
Mass spectrograph
Neutrino detector
Radar
Sonar
Radio interferometer
Richter scale
Scanning tunneling microscope
Synchrocyclotron
Tevatron accelerator
Ultracentrifuge
Ultramicroscope
Vending machine slug rejector
X-ray crystallography
Medical procedures
Amniocentesis
Blood transfusion
CAT scanner
Cloning
Coronary artery bypass surgery
Electrocardiogram

920 / Topics by Category
Electroencephalogram
Heart-lung machine
Iron lung
Laser eye surgery
Laser vaporization
Mammography
Nuclear magnetic resonance
Pap test
Syphilis test
Ultrasound
X-ray image intensifier
Medicine
Abortion pill
Amniocentesis
Antibacterial drugs
Artificial blood
Artificial heart
Artificial hormone
Artificial kidney
Birth control pill
Blood transfusion
CAT scanner
Contact lenses
Coronary artery bypass surgery
Electrocardiogram
Electroencephalogram
Genetically engineered insulin
Hearing aid
Heart-lung machine
Iron lung
Laser eye surgery
Laser vaporization
Mammography
Nuclear magnetic resonance
Pacemaker
Pap test
Penicillin
Polio vaccine (Sabin)
Polio vaccine (Salk)
Reserpine
Salvarsan
Syphilis test
Tuberculosis vaccine
Typhus vaccine
Ultrasound
X-ray image intensifier
Yellow fever vaccine
Music
Broadcaster guitar
Cassette recording
Dolby noise reduction
Electronic synthesizer
FM Radio
Radio
Transistor radio
Photography
Autochrome plate
Brownie camera
Color film
Electrocardiogram
Electron microscope
Fax machine
Holography
Infrared photography
Instant photography
Mammography
Mass spectrograph
Optical disk
Talking motion pictures
Weather satellite

Xerography
X-ray crystallography
Physics
Atomic bomb
Cyclotron
Electron microscope
Field ion microscope
Geiger counter
Hydrogen bomb
Holography
Laser
Mass spectrograph
Scanning tunneling microscope
Synchrocyclotron
Tevatron accelerator
X-ray crystallography
Synthetics
Artificial blood
Artificial chromosome
Artificial heart
Artificial hormone
Artificial insemination
Artificial kidney
Artificial satellite
Aspartame
Buna rubber
Cyclamate
Electronic synthesizer
Genetically engineered insulin
Neoprene
Topics by Category / 921
Synthetic amino acid
Synthetic DNA
Synthetic RNA
Vat dye
Transportation
Airplane
Atomic-powered ship
Bullet train
Diesel locomotive
Dirigible
Gas-electric car
Gyrocompass
Hovercraft
Internal combustion engine
Supersonic passenger plane
Turbojet
Weapons technology
Airplane
Atomic bomb
Cruise missile
Dirigible
Hydrogen bomb
Propeller-coordinated machine
gun
Radar
Rocket
Sonar
Stealth aircraft
V-2 rocket

This Page Intentionally Left Blank

Index
Index
Abbe, Ernst, 678
ABC. See American Broadcasting
Company
Abel, John Jacob, 50, 58, 60
Abortion pill, 1-5
Adams, Ansel, 430
Adams, Thomas, 850
Advanced Research Projects Agency,
446-447
AHD. See Audio high density disc
Aiken, Howard H., 187, 417, 490, 828
Airplane, 6-10
Aldrin, Edwin, 8
Alferov, Zhores I., 320-321
Alkaline storage battery, 11-15
Ambrose, James, 167
American Broadcasting Company, 215
American Telephone and Telegraph
Company, 741
Amery, Julian, 714
Amino acid, synthetic, 724-728
Ammonia, 16-19; and atomic clock, 81-
82; as a refrigerant, 290-291, 345,
631, 746
Amniocentesis, 20-23
Anable, Gloria Hollister, 100
Anschütz-Kaempfe, Hermann, 382
Antibacterial drugs, 24-27
Antibiotics, 24-27, 47, 813; penicillin,
553-557, 676, 738
Apple II computer, 28-32
Appliances. See Electric clock; Electric
refrigerator; Microwave cooking;
Refrigerant gas; Robot (household);
Vacuum cleaner; Washing machine
Aqualung, 33-37
Archaeology, 158-162
Archimedes, 687
Armstrong, Edwin H., 339
Armstrong, Neil, 8
Arnold, Harold D., 477
Arnold, Henry Harley, 807
ARPAnet, 447-448
Arsonval, Jacques Arsène d’, 351
Arteries and laser vaporization, 472-476
Artificial blood, 38-40
Artificial chromosome, 41-44
Artificial heart, 45-49
Artificial hormone, 50-53
Artificial insemination, 54-57
Artificial intelligence, 668, 671, 864
Artificial kidney, 58-62
Artificial satellite, 63-66
Artificial sweeteners, 67-70;
Aspartame, 67-70; cyclamates, 248-
251
ASCC. See Automatic Sequence
Controlled Calculator
Aspartame, 67-70
Assembly line, 71-75, 197, 434, 436, 439
Aston, Francis William, 494, 496
Astronauts, 749, 848
AT&T. See American Telephone and
Telegraph Company
Atanasoff, John Vincent, 312
Atomic bomb, 76-79, 84, 118-119, 255,
412, 414, 521, 525, 697, 721
Atomic clock, 80-83
Atomic Energy Commission, 119, 521,
523
Atomic force microscope, 681
Atomic mass, 494-497
Atomic-powered ship, 84, 86-87
Audiffren, Marcel, 289
Audio high density disc, 220
Audrieth, Ludwig Frederick, 67
Autochrome plate, 88-91
Automatic Sequence Controlled
Calculator, 187
Automobiles; and assembly lines, 71,
75; and interchangeable parts, 434-
441; and internal combustion
engine, 442-445
Avery, Oswald T., 733
Aviation. See Airplane; Dirigible;
Rockets; Stealth aircraft; Supersonic
passenger plane; Turbojet
Babbage, Charles, 417
Backus, John, 347
923

924 / Index
Bacon, Francis Thomas, 355, 358
Baekeland, Leo Hendrik, 571
Baeyer, Adolf von, 571
Bahcall, John Norris, 511
Bain, Alexander, 316
Baker, William Oliver, 172, 174
Banting, Frederick G., 375
Baran, Paul, 446
Bardeen, John, 782, 786, 789
Barnay, Antoine, 663
Barton, Otis, 95, 100
BASIC computer language, 29-30, 92-
94, 559
Bathyscaphe, 95-99
Bathysphere, 100-103
Batteries, 11, 227; alkaline storage, 11-
15; and electric cars, 360, 363; and
fuel cells, 356; and hearing aids, 390,
392; and pacemakers, 547; silicon
solar, 569; and transistor radios, 780,
875, 878
Battery jars, 454, 607
Baulieu, Étienne-Émile, 1-2
Bavolek, Cecelia, 394
Bazooka, 659
BCS theory, 789
Beams, Jesse W., 815
Becquerel, Alexandre-Edmond, 562
Becquerel, Antoine-Henri, 365
Beebe, William, 95, 100
Bélanger, Alain, 1
Bell, Alexander Graham, 320-322, 390,
482-483, 663-665
Bell Telephone Laboratories, 101, 138-
140, 172-173, 204-205, 217, 229-230,
323, 390-391, 482, 567, 614, 625, 678,
744, 752, 774-775, 778-779, 786, 829,
840, 861, 863, 876
Belzel, George, 558
Benedictus, Edouard, 454
Bennett, Frederick, 434
Bennett, W. R., 217
Berger, Hans, 298
Bergeron, Tor, 183
Berliner, Emil, 279
Berthelot, Marcellin Pierre, 597
Bessemer, Henry, 701, 704
Bessemer converter, 701-702, 704
Best, Charles H., 375
Bethe, Hans, 412, 720
Bevis, Douglas, 20
Billiard balls, 572-573
BINAC. See Binary Automatic
Computer
Binary Automatic Computer, 104-107,
315, 330, 348
Binnig, Gerd, 678, 680
Birdseye, Clarence, 343
Birth control pill, 108-112
Bissell, Melville R., 832
Blodgett, Katherine Ann, 454
Blood plasma, 38
Blood transfusion, 113-117
Bobeck, Andrew H., 138-139
Bohn, René, 842
Bohr, Niels, 76, 520, 695
Bolton, Elmer Keiser, 507, 529
Booth, Andrew D., 330
Booth, H. Cecil, 832, 835
Borlaug, Norman E., 638, 643
Borsini, Fred, 151
Bothe, Walter, 367
Bragg, Lawrence, 896, 898
Bragg, William Henry, 896, 898
Brain, and nuclear magnetic
resonance, 516, 519
Brattain, Walter H., 782, 786, 789
Braun, Wernher von, 63, 871
Bravais, Auguste, 896
Breast cancer, 486, 489
Breeder reactor, 118-121
Broadcaster guitar, 122-129
Broadcasting. See FM radio; Radio;
Radio crystal sets; Television;
Transistor radio
Broglie, Louis de, 302, 678
Brooks, Fred P., 866
Brownell, Frank A., 130
Brownie camera, 130-137
Bubble memory, 138-141
Buehler, William, 498
Bullet train, 142-145
Buna rubber, 146-150
Burks, Arthur Walter, 312
Burton, William M., 765
Busch, Adolphus, 259
Busch, Hans, 302, 679
Bush, Vannevar, 262, 264

CAD. See Computer-Aided Design
CAD/CAM, 151-157
Calculators; desktop, 232; digital, 490-
493; electromechanical, 313;
mechanical, 104; pocket, 576-580;
punched-card, 104
California Institute of Technology, 646,
731, 782
Callus tissue, 421
Calmette, Albert, 791
Cameras; Brownie, 130-137; and film,
88-91, 192-195; and infrared film,
426; instant, 430-433; in space, 887-
889; video, 165, 859; and virtual
reality, 867; and X rays, 901-904. See
also Photography
Campbell, Charles J., 468
Campbell, Keith H. S., 177
Cancer, 4, 324, 376; and cyclamates, 69,
249-250; and infrared photography,
428; and mammography, 486-489;
therapy, 40; uterine, 549-552
Capek, Karel, 650, 654
Carbohydrates, 374
Carbon dating, 158-162
Carlson, Chester F., 891, 893
Carnot, Sadi, 398
Carothers, Wallace H., 507, 510, 529,
574, 589
Carrel, Alexis, 113
Carty, John J., 477, 484
Cary, Frank, 558
Cascariolo, Vincenzo, 335
Cassette recording, 163-166, 221, 223,
279, 538; and Dolby noise reduction,
282; and microcomputers, 386; and
Sony Walkman, 788; and transistors,
784
CAT scanner, 167-171
Cathode-ray tubes, 170, 303, 315, 326,
564, 611; and television, 757-758,
760, 837
Caton, Richard, 298
CBS. See Columbia Broadcasting
System
CD. See Compact disc
CDC. See Control Data Corporation
Cell phone, 172-176
Celluloid, 454, 571-573
Centrifuge, 815-818
Index / 925
Cerf, Vinton G., 446, 448
Chadwick, James, 367
Chain, Ernst Boris, 553
Chamberlain, W. Edward, 901
Chance, Ronald E., 374
Chandler, Robert F., Jr., 638
Chang, Min-Chueh, 108
Chanute, Octave, 6
Chapin, Daryl M., 567
Chardonnet, Hilaire de, 589
Chemotherapy, 24, 40, 676
Cho, Fujio, 360
Christian, Charlie, 122, 126
Chromosomes. See Artificial
chromosome
Clark, Barney, 45
Clark, Dugold, 257
Clarke, Arthur C., 63, 204
Cloning, 177-182
Cloud seeding, 183-186
Coal tars, 593, 843
COBOL computer language, 92, 187-
191, 350
Cockerell, Christopher Sydney, 407
Cohen, Robert Waley, 442
Coleman, William T., Jr., 714
Collins, Arnold Miller, 507
Color film, 192-195
Color photography, 88-91
Color television, 196-199
Colossus computer, 200-203
Columbia Broadcasting System, 196,
215, 830
Communications satellite, 204-207
Community antenna television, 208-216
Compaan, Klaas, 537
Compact disc, 217-224
Compressed-air-accumulating power
plant, 225-228
Computer-Aided Design (CAD), 151-
157
Computer chips, 140, 229-234
Computer languages, 154; ALGOL, 92-
93; BASIC, 29-30, 92-94, 559;
COBOL, 92, 187-191, 350;
FORTRAN, 92-93, 189, 347-350
Computerized axial tomography, 167-
171
Computers; and information storage,

926 / Index
104-107, 138-141, 165, 330-334, 386-
389, 537-540; and Internet, 446-450.
See also Apple II computer; Personal
computers
Concorde, 714-719
Condamine, Charles de la, 146
Contact lenses, 235-239
Conti, Piero Ginori, 378
Contraception, 1-5, 108-112
Control Data Corporation, 709, 711
Cooking; microwave, 502-506; and
Pyrex glass, 607, 609; and Tefloncoating,
748-749
Coolidge, William David, 795
Cormack, Allan M., 167
Corning Glass Works, 323, 606-610
Coronary artery bypass surgery, 240-
243
Cource, Geoffroy de, 714, 716
Cousins, Morison, 799
Cousteau, Jacques-Yves, 33, 35, 102
Cray, Seymour R., 709, 711-712
Crick, Francis, 41, 177, 729, 733
Crile, George Washington, 113
Critical mass, 77, 119, 521
Crookes, William, 365
CRT. See Cathode-ray tubes
Cruise missile, 244-247
Curie, Jacques, 692
Curie, Marie, 823
Curie, Pierre, 692, 695
Curtis, William C., 611-612
Cyclamate, 248-251
Cyclotron, 252-256
DAD. See Digital audio disc
Daimler, Gottlieb, 257
Dale, Henry Hallett, 50
Damadian, Raymond, 516
Datamath, 579
Davis, Raymond, Jr., 511
Deep-sea diving, 95-103
De Forest, Lee, 477-478, 480, 483, 837-
838
Dekker, Wisse, 217
Deoxyribonucleic acid; characteristics,
733. See also DNA
Depp, Wallace Andrew, 751
Desert Storm, 699
Devol, George C., Jr., 654
DeVries, William Castle, 45-46
Diabetes, 51-52, 374-377
Dichlorodifluoromethane, 630-633
Diesel, Rudolf, 257-258
Diesel locomotive, 257-261
Differential analyzer, 262-266
Digital audio disc, 219
Dirigible, 267-271
Disposable razor, 272-278
Diving. See Aqualung
DNA, 41, 177; and artificial
chromosomes, 41-44; and cloning,
177; and genetic “fingerprinting,”
370-373; recombinant, 41; synthetic,
729-732; and X-ray crystallography,
900. See also Deoxyribonucleic acid;
Synthetic DNA
Dolby, Ray Milton, 279, 281
Dolby noise reduction, 279-283
Domagk, Gerhard, 24
Donald, Ian T., 823-824
Dornberger, Walter Robert, 871
Drew, Charles, 113, 115
Drinker, Philip, 451
Dulbecco, Renato, 581
Dunwoody, H. H., 621
Du Pont. See Du Pont de Nemours and
Company
Du Pont de Nemours and Company,
77, 149, 248, 508-509, 529, 531, 542,
589-590, 746-748, 799, 803
Durfee, Benjamin M., 490
Durham, Eddie, 126
Durrer, Robert, 701
Dyes, 593; and acrylics, 543; and
infrared radiation, 425, 428; and
microorganism staining, 24-25; and
photographic film, 192-194; poison,
674; and polyesters, 591; vat, 842-
845
Earthquakes, measuring of, 645-649
Eastman, George, 130, 135
Eckert, John Presper, 104, 312, 828
Edison, Thomas Alva, 11, 335, 479, 616,
744, 839; and batteries, 12-14; and
Edison effect, 837; and electric light,
795, 832; and fluoroscope, 901; and
phonograph, 217, 279

Edison effect, 837-838
Edlefsen, Niels, 252
EDVAC. See Electronic Discrete
Variable Automatic Computer
Effler, Donald B., 240
Ehrlich, Paul, 24, 673
Einstein, Albert, 82, 472, 497, 563, 695,
721
Einthoven, Willem, 293, 295
Eisenhower, Dwight D., 84, 415
Elastomers, 148, 507-510, 598
Electric clock, 284-288
Electric refrigerator, 289-292
Electricity, generation of, 79, 378, 569
Electrocardiogram, 293-297
Electroencephalogram, 298-301
Electrolyte detector, 479
Electron microscope, 302-306, 403, 902
Electron theory, 562-565
Electronic Discrete Variable Automatic
Computer, 105-107, 314, 829
Electronic Numerical Integrator and
Calculator, 105-106, 312-315, 347,
668, 829
Electronic synthesizer, 307-311
Eli Lilly Research Laboratories, 374-377
Elliott, Tom, 360
Elmquist, Rune, 545
Elster, Julius, 562, 564
Engelberger, Joseph F., 654
ENIAC. See Electronic Numerical
Integrator and Calculator
Ericsson, John, 687
Espinosa, Chris, 28
Estridge, Philip D., 386
Evans, Oliver, 71
Ewan, Harold Irving, 625
“Excalibur,” 416
Eyeglasses; and contact lenses, 235-239
; frames, 498, 500; and hearing aids,
391, 787
Fabrics; and dyes, 842-845; orlon, 541-
544; polyester, 589-592; and washing
machines, 883-886
Fahlberg, Constantin, 67
Fasteners, velcro, 846-849
Favaloro, Rene, 240
Fax machine, 316-319
Index / 927
FCC. See Federal Communications
Commission
Federal Communications Commission;
and cell phones, 173, 175; and
communication satellites, 204; and
FM radio, 341; and microwave
cooking, 505; and television, 196-
197, 208-210
Fefrenkiel, Richard H., 172
Feinbloom, William, 235, 237
Fender, Leo, 122
Ferguson, Charles Wesley, 158
Fermi, Enrico, 76, 84, 412, 520, 525
Fessenden, Reginald, 13, 477-480, 616-
618
Fiber-optics, 320-324
Fick, Adolf Eugen, 235
Field ion microscope, 325-329, 679
FIM. See Field ion microscope
Finlay, Carlos J., 905
Fischer, Rudolf, 192
Fisher, Alva J., 883
Fleming, Alexander, 553, 555
Fleming, John Ambrose, 478, 621, 837,
839
Flick, J. B., 394
Floppy disk, 330-334
Florey, Baron, 553
Flosdorf, Earl W., 351
Flowers, Thomas H., 200
FLOW-MATIC, 187
Fluorescent lighting, 335-338
FM radio, 339-342
Fokker, Anthony Herman Gerard, 601,
603
Food; artificial sweeteners, 67-70, 248-
251; freeze-drying, 351-354;
freezing, 343-346; microwave
cooking, 502-506; packaging, 598-
599; and refrigeration, 289-292, 343-
346, 630, 632; rice and wheat, 638-
644; storage, 799-806
Food and Drug Administration, 45,
111, 375
Ford, Henry, 11, 71, 74, 257, 434
Forel, François-Alphonse, 645
Forest de Bélidor, Bernard, 770
FORTRAN programming language,
92-93, 189, 347-350
Foucault, Jean-Bernard-Léon, 382

928 / Index
Fox Network, 215
Francis, Thomas, Jr., 585
Freeze-drying, 351-354
Frerichs, Friedrick von, 673
Frisch, Otto Robert, 76, 520
Fuchs, Klaus Emil Julius, 412
Fuel cell, 355-359
Fuller, Calvin S., 567
Fulton, Robert, 335
Gabor, Dennis, 402, 404
Gagarin, Yuri A., 874
Gagnan, Émile, 33, 102
Gamow, George, 325, 412, 414, 720-721
Garcia, Celso-Ramon, 108
Garros, Roland, 601
Garwin, Richard L., 414
Gas-electric car, 360-364
Gates, Bill, 92, 94
Gaud, William S., 638
Gautheret, Roger, 421
GE. See General Electric Company
Geiger, Hans, 365, 367
Geiger counter, 365-369
Geissler, Heinrich, 335
Geitel, Hans Friedrich, 562, 564
General Electric Company, 101, 183-
185, 219, 264, 290, 341, 356, 384, 440,
455, 477, 617, 683, 685, 795-796, 809,
840, 863, 893, 902
Genetic “fingerprinting,” 370-373
Genetically engineered insulin, 374-377
Geothermal power, 378-381
Gerhardt, Charles, 597
Gershon-Cohen, Jacob, 486
Gibbon, John H., Jr., 394
Gibbon, Mary Hopkinson, 394
Gillette, George, 272
Gillette, King Camp, 272, 276
Glass; coloring of, 819-820; fibers, 322-
323, 591; food containers, 800; goldruby,
819; high-purity, 322;
laminated, 454-458; Pyrex, 606-610
Glass fiber. See Fiber-optics
Goddard, Robert H., 63, 65, 658, 660,
662
Goldmark, Peter Carl, 196
Goldstine, Herman Heine, 312, 347
Goodman, Benny, 126
Goodyear, Charles, 146-147, 335
Gosslau, Ing Fritz, 871
Gould, R. Gordon, 472
Goulian, Mehran, 729
Graf Zeppelin, 271
Gray, Elisha, 663
Greaves, Ronald I. N., 351
Green Revolution, 638-639, 641-644
Grove, William Robert, 355
Groves, Leslie R., 76, 747
Grunberg-Manago, Marianne, 733
Guérin, Camille, 791
Guitar, electric, 122-129
Gutenberg, Beno, 645
Gyrocompass, 382-385
Haas, Georg, 59
Haber, Fritz, 16-19
Haberlandt, Gottlieb, 421
Hahn, Otto, 84, 520
Haldane, John Burdon Sanderson, 724
Haldane, T. G. N., 398
Hall, Charles, 335
Halliday, Don, 151
Hallwachs, Wilhelm, 562
Hamilton, Francis E., 490
Hammond, John, 126
Hanratty, Patrick, 151
Hard disk, 386-389
Hata, Sahachiro, 673
Haüy, René-Just, 896
Hayato, Ikeda, 142
Hayes, Arthur H., Jr., 67
Hazen, Harold L., 262
Health Company, 650
Hearing aid, 390-393
Heart; and pacemakers, 545-548. See
also Artificial heart
Heart-lung machine, 394-397
Heat pump, 398-401
Heilborn, Jacob, 272
Henne, Albert, 630, 746
Hero (Greek mathematician), 851
Hero 1 robot, 650-653
Herschel, William, 425, 427
Hertz, Heinrich, 502, 621
Heumann, Karl, 842
Hewitt, Peter Cooper, 335

Hindenburg, 271
Hitler, Adolf, 414, 509, 807, 871
Hoff, Marcian Edward, Jr., 229
Hoffman, Frederick de, 413
Hoffmann, Erich, 676
Hofmann, August Wilhelm von, 593,
842, 844
Hollerith, Herman, 417
Holography, 402-406, 537
Homolka, Benno, 192
Honda Insight, 360
Hoover, Charles Wilson, Jr., 751
Hoover, William Henry, 832
Hopper, Grace Murray, 187-188
Hormones. See Artificial hormone
Hounsfield, Godfrey Newbold, 167,
169
House appliances. See Appliances
Houtz, Ray C., 541
Hovercraft, 407-411
Howe, Elias, 335
Hughes, Howard R., 533, 535
Hulst, Hendrik Christoffel van de, 625
Humphreys, Robert E., 765
Humulin, 374, 377
Hyatt, John Wesley, 571, 573
Hyde, James Franklin, 683
Hydrofoil, 665
Hydrogen bomb, 412-416
IBM. See International Business Machines
IBM Model 1401 computer, 417-420
Ibuka, Masaru, 778, 786, 875, 879
ICBM. See Intercontinental ballistic
missiles
Idaho National Engineering
Laboratory, 119, 521
Immelmann, Max, 601
Immunology. See Polio vaccine;
Tuberculosis vaccine; Typhus
vaccine; Yellow fever vaccine
In vitro plant culture, 108, 421-424
INEL. See Idaho National Engineering
Laboratory
Infantile paralysis. See Polio
Infrared photography, 425-429
Instant photography, 430-433
Insulin, genetically engineered, 374-377
Index / 929
Intel Corporation, 153, 232, 234, 559
Interchangeable parts, 434-441
Intercontinental ballistic missiles, 63-64
Internal combustion engine, 442-445
International Business Machines, 31,
140, 187, 189, 313, 330-331, 333, 347-
350, 386, 388, 395, 420, 490-493, 680-
681, 830, 861-865; Model 1401
computer, 417-420; personal
computers, 558-561
Internet, 446-450
Iron lung, 451-453
Isotopes, and atomic mass, 494
Ivanov, Ilya Ivanovich, 54
Ives, Frederick E., 90
Jansky, Karl, 614, 625
Jarvik, Robert, 45
Jarvik-7, 45, 49
The Jazz Singer, 742
Jeffreys, Alec, 370
Jenkins, Charles F., 756
Jet engines; and hovercraft, 408, 410;
impulse, 871; and missiles, 244;
supersonic, 714-719; turbo, 807-810
Jobs, Steven, 28, 30
Johnson, Irving S., 374
Johnson, Lyndon B., 206
Johnson, Reynold B., 330
Joliot, Frédéric, 76
Jolson, Al, 742
Jones, Amanda Theodosia, 343, 345
Joyce, John, 272
Judson, Walter E., 634
Judson, Whitcomb L., 847
Kahn, Reuben Leon, 737
Kamm, Oliver, 50
Kao, Charles K., 320
Kelvin, Lord, 398
Kemeny, John G., 92
Kettering, Charles F., 11, 630
Kidneys, 58, 62, 374; and blood, 39;
and cyclamate, 248; problems, 634
Kilby, Jack St. Clair, 151, 229, 231, 576,
578
Kipping, Frederic Stanley, 683
Kitchenware. See Polystyrene; Pyrex
glass; Teflon; Tupperware

930 / Index
Knoll, Max, 302
Kober, Theodor, 267
Koch, Robert, 791
Kolff, Willem Johan, 58
Kornberg, Arthur, 729
Kornei, Otto, 891
Korolev, Sergei P., 63-64
Kramer, Piet, 537
Krueger, Myron W., 866
Kruiff, George T. de, 537
Kunitsky, R. W., 54
Kurtz, Thomas E., 92
Lake, Clair D., 490
Laminated glass, 454-458
Land, Edwin Herbert, 430, 432
Langévin, Paul, 692, 695, 823
Langmuir, Irving, 183
Laser, 459-463
Laser-diode recording process, 464-467
Laser eye surgery, 468-472
Laser vaporization, 472-476
Laservision, 219, 465
Laue, Max von, 896
Lauterbur, Paul C., 516
Lawrence, Ernest Orlando, 252, 254,
720
Lawrence-Livermore National
Laboratory, 416, 671
Leclanché, Georges, 355
Leeuwenhoek, Antoni van, 678
Leith, Emmett, 402
Leland, Henry M., 434, 437
Lengyel, Peter, 733
Lenses; camera, 130, 132-134;
electromagnetic, 303; electron, 302-
303; and fax machines, 317; and
laser diodes, 465; microscope, 678;
and optical disks, 539; Pyrex, 609;
railroad lantern, 606; scleral, 235;
television camera, 887; and
xerography, 891-894. See also
Contact lenses
Leonardo da Vinci, 235
Leverone, Louis E., 850
Leverone, Nathaniel, 850
Lewis, Thomas, 293
LGOL computer language, 92-93
Libby, Willard Frank, 158, 160
Lidwell, Mark, 545
Lincoln, Abraham, 320, 439
Lindbergh, Charles A., 661
Littleton, Jesse T., 606, 608
Livestock, artificial insemination of,
54-57
Livingston, M. Stanley, 252
Locke, Walter M., 244
Lockhead Corporation, 697
Long-distance radiotelephony, 477-
481
Long-distance telephone, 482-485
Loosley, F. A., 701
Lumière, Auguste, 88-89
Lumière, Louis, 88-89
Lynde, Frederick C., 850-851
Lyons, Harold, 80
McCabe, B. C., 378
McCormick, Cyrus Hall, 335
McCormick, Katherine Dexter, 108
McCune, William J., 430
Machine guns, 601-605
McKay, Dean, 558
McKenna, Regis, 28
McKhann, Charles F., III, 451
McMillan, Edwin Mattison, 720
McWhir, J., 177
Magnetron, 504
Maiman, Theodore Harold, 320, 459,
468, 472
Mallory, Joseph, 432
Mammography, 486-489
Manhattan Project, 77-78, 412, 414, 525,
747-748
Mansfield, Peter, 516
Marconi, Guglielmo, 477, 616, 619, 621,
839
Mariano di Jacopo detto Taccola, 770
Mark I calculator, 490-493
Marrison, Warren Alvin, 284, 286
Marsden, Ernest, 367
Mass spectrograph, 494-497
Massachusetts Institute of Technology,
861
Mauchly, John W., 104, 312, 347, 828
Maxwell, James Clerk, 88, 502, 621
Meitner, Lise, 76, 520
Memory metal, 498-501

Mercalli, Giuseppe, 645
Merrill, John P., 61
Merryman, Jerry D., 576, 578
Mestral, Georges de, 846, 848
Metchnikoff, Élie, 673-674
Microprocessors, 94, 229-234, 287, 419,
538
Microscopes; atomic force, 681;
electron, 302-306, 403, 902; field ion,
325-329, 679; scanning tunneling,
678-682; ultra-, 819-822
Microvelcro, 847
Microwave cooking, 502-506
Midgley, Thomas, Jr., 444, 630, 746
Miller, Bernard J., 394
Miller, Stanley Lloyd, 724
Millikan, Robert A., 646
Millikan, Robert Andrews, 722
Milunsky, Aubrey, 20
Missiles; cruise, 244-247; guided, 385;
intercontinental, 63-64; Sidewinder,
698; Snark, 106. See also Rockets; V-2
rocket
Mixter, Samuel Jason, 113
Mobile Telephone Service, 172
Model T, 14, 71, 75, 439-440
Monitor, 687
Monocot plants, 422
Monomers, 148, 541, 590-591
Moog, Robert A., 307, 309
Moon; distance to, 462; and lasers, 459;
and radar, 614; and radio signals,
614
Morel, Georges Michel, 421-423
Morganthaler, Ottmar, 335
Morita, Akio, 217, 222, 778, 786, 875
Morse, Samuel F. B., 320, 335
Morse code, 477, 616, 621
Motion picture sound, 741-745
Mouchout, Augustin, 687
Movies. See Talking motion pictures
Müller, Erwin Wilhelm, 325, 327, 679
Murray, Andrew W., 41
Murrow, Edward R., 830
Naito, Ryoichi, 38
National Broadcasting Company, 198,
215
National Geographic, 665
Index / 931
National Geographic Society, 665
National Radio Astronomy
Observatory, 628
Natta, Giulio, 593
Nautilus, 84, 521
NBC. See National Broadcasting
Company
Neoprene, 507-510
Neumann, John von, 92, 104, 312, 347,
710, 828
Neurophysiology, 298, 300
Neutrino detector, 511-515
Newman, Max H. A., 200
Newton, Isaac, 659
Nickerson, William Emery, 272
Nieuwland, Julius Arthur, 507
Nipkow, Paul Gottlieb, 756
Nirenberg, Marshall W., 733
Nitinol, 498-501
Nitrogen, 16
Nobécourt, P., 421
Nobel Prize winners, 174; Chemistry,
16, 18-19, 50, 52, 158, 160, 183, 455,
494, 496, 595, 720, 724, 819, 821-822;
Physics, 229, 231, 252, 254-255, 302,
304, 321, 402, 404, 459, 520, 619, 678,
680, 782, 789, 896-898; Physiology
or Medicine, 24, 41, 167, 169, 293,
295, 375, 553, 555, 581, 674, 676, 730,
733
Nordwestdeutsche Kraftwerke, 225
Northrop Corporation, 106, 697
Noyce, Robert, 151, 229
NSFnet, 447
Nuclear fission, 76, 84, 118-121, 185,
412, 520-528
Nuclear fusion, 78
Nuclear magnetic resonance, 516-519
Nuclear power plant, 520-524
Nuclear reactor, 118-121, 520-528
Nylon, 510, 529-532, 541, 574, 590;
Helance, 591; and velcro, 846-847
Oak Ridge National Laboratory, 77,
525-528
Ochoa, Severo, 733
Ohain, Hans Pabst von, 807
Ohga, Norio, 875
Oil-well drilling, 345, 533-536
Oparin, Aleksandr Ivanovich, 724

932 / Index
Opel, John, 558
Ophthalmology, 468
Oppenheimer, J. Robert, 76, 325
Optical disk, 537-540
Orlon, 541-544
Ottens, Lou F., 537
Otto, Nikolaus, 257
Oxytocin, 50
Pacemaker, 545-548
Painter, William, 272
Paley, William S., 196
Pap test, 549-552
Papanicolaou, George N., 549
Parsons, Charles, 378
Parsons, Ed, 208
Particle accelerators, 252, 256, 720-723,
761-764
Paul, Les, 122
Pauli, Wolfgang, 511
PC. See Personal computers
PCM. See Pulse code modulation
Pearson, Gerald L., 567
Penicillin, 553-557
Peoples, John, 761
Perkin, William Henry, 842, 844
Perrin, Jean, 695
Persian Gulf War, 246, 698-699
Personal computers, 153, 558-561, 864;
Apple, 28-32; and floppy disks, 332-
333; and hard disks, 389; and
Internet, 447, 449
Pfleumer, Fritz, 163
Philibert, Daniel, 1
Philips Corporation, 464, 857
Photocopying. See Xerography
Photoelectric cell, 562-566
Photography; film, 88-91, 192-195, 430-
433. See also Cameras
Photovoltaic cell, 567-570
Piccard, Auguste, 36, 95, 97, 103
Piccard, Jacques, 95
Piccard, Jean-Félix, 97
Pickard, Greenleaf W., 621
Pierce, John R., 204
Pincus, Gregory, 108
Planck, Max, 563
Plastic, 571-575; Tupperware, 799-806
Plunkett, Roy J., 746, 748
Pocket calculator, 576-580
Polaroid camera, 170, 430-433
Polio, 451-453
Polio vaccine, 581-588
Polyacrylonitrile, 541-543
Polyester, 589-592
Polyethylene, 593-596
Polystyrene, 597-600
Porter, Steven, 272
Powers, Gary, 245
Pregnancy. See Abortion pill;
Amniocentesis; Birth control pill;
Ultrasound
Priestley, Joseph, 146
Propeller-coordinated machine gun,
601-605
Protein synthesis, 735
Prout, William, 494
Pulse code modulation, 217-220
Purcell, Edward Mills, 625
Purvis, Merton Brown, 751
Pye, David Randall, 442
Pyrex glass, 606-610
Quadrophonic sound, 221
Quantum theory, 563
Quartz crystals, 81, 284-288
Radar, 229, 265, 314, 391, 504, 611-612,
614-615; and sonar, 693, 824; and
bathyscaphe, 96; and laser
holography, 405; and stealth aircraft,
697-699
Radio, 616-620; FM, 339-342
Radio Corporation of America, 196-
199, 210, 213, 219, 340-341, 464, 537,
618-619, 741, 758-759, 787
Radio crystal sets, 621-624
Radio frequency, 616; and cell phones,
172, 175; and crystral radio, 622; and
microwave heating, 505
Radio interferometer, 625-629
Radioactivity, 720, 734; and barium, 76,
520; carbon dating, 158-162; and
DNA, 371; and isotopes, 494, 497;
measuring, 365-369; and neutrinos,
511-512
Radiotelephony, 477-481
Rainfall, induced, 183-186
RAM. See Random access memory

Random access memory, 140, 387, 559,
861-862, 864
Raytheon Company, 503, 505, 786
Razors, 272-278
RCA. See Radio Corporation of
America
Reagan, Ronald, 415
Reber, Grote, 625
Recombinant DNA, 41
Recording; cassettes, 163-166, 538, 784,
788, 875-882; compact discs, 217-224;
Dolby noise reduction, 279-283;
laser-diodes, 464-467; sound, 741-
742; video, 857-860
Reed, Walter, 905
Refrigerant gas, 630-633
Reichenbach, Henry M., 130
Rein, Herbert, 541
Remsen, Ira, 67
Reserpine, 634-637
Ribonucleic acid, 734. See also Synthetic
RNA
Ricardo, Harry Ralph, 442
Rice and wheat strains, 638-644
Rice-Wray, Edris, 108
Richter, Charles F., 645-646
Richter scale, 645-649
Rickover, Hyman G., 520
Riffolt, Nils, 661
Ritchie, W. A., 177
Rizzo, Paul, 558
RNA, synthetic, 733-736
Robot, household, 650-653
Robot, industrial, 654-657
Rochow, Eugene G., 683, 685
Rock, John, 108
Rockets; and satellites, 63-66; design,
712; liquid-fuel-propelled, 658-662,
871-874. See also Missiles
Rogers, Howard G., 430
Rohrer, Heinrich, 678, 680
Röntgen, Wilhelm Conrad, 167, 365,
896, 901
Roosevelt, Franklin D., 264, 588, 770-771
Root, Elisha King, 71
Rosen, Charles, 362
Rosing, Boris von, 758
Rossi, Michele Stefano de, 645
Rotary cone drill bit, 533, 536
Index / 933
Rotary dial telephone, 663-667, 751,
774-776
Rotary engine, 362
Roux, Pierre-Paul-Émile, 673
Rubber, synthetic, 146-150, 507-510,
530, 593, 595
Ruska, Ernst, 302, 304, 678, 680
Russell, Archibald, 714
Rutherford, Ernest, 252, 365-368, 455,
494, 564, 720-721, 898
Ryle, Martin, 625
Sabin, Albert Bruce, 581, 583
Saccharin, 248
Sachs, Henry, 272
SAINT, 668-672
Salk, Jonas Edward, 581, 585-586
Salomon, Albert, 486
Salvarsan, 673-674, 676-677
Sanger, Margaret, 108, 110, 112
Sarnoff, David, 196-197, 210, 339-340,
758
Satellite, artificial, 63-66
Satre, Pierre, 714
Saulnier, Raymond, 601
Savannah, 85
Sawyer, Wilbur Augustus, 905
Sayer, Gerry, 807
Scanning tunneling microscope, 678-682
Schaefer, Vincent Joseph, 183
Schaudinn, Fritz, 673
Schawlow, Arthur L., 459
Schlatter, James M., 67
Schmidt, Paul, 871
Scholl, Roland, 842
Schönbein, Christian Friedrich, 571
Schrieffer, J. Robert, 789
SDI. See Strategic Defense Initiative
Selectavision, 219
Semiconductors, 139-140, 218, 229-234,
317, 464-466, 568, 786-787, 892; and
calculators, 577, 579; defined, 229,
232, 891
Senning, Ake, 545
Serviss, Garrett P., 659
Seyewetz, Alphonse, 88
Shannon, Claude, 868
Sharp, Walter B., 533, 535
Sharpey-Schafer, Edward Albert, 50

934 / Index
Shaw, Louis, 451
Shaw, Ronald A., 407
Sheep, cloning of, 177-182
Shellac, 572
Shockley, William B., 229, 778, 782, 786,
789
Shroud of Turin, 161
Shugart, Alan, 330, 386
Shuman, Frank, 687
Sidewinder missile, 698
Siedentopf, H. F. W., 819
Siegrist, H., 192
Silicones, 683-686
Simon, Edward, 597
The Singing Fool, 742
Sinjou, Joop, 537
Sinsheimer, Robert L., 729
Sketchpad, 868
Slagle, James R., 668, 671
Sloan, David, 252
Smith, Hugh, 905
Smith, Robert, 427
Smouluchowski, Max von, 819
Snark missile, 106
Snyder, Howard, 883
Sogo, Shinji, 142
Solar energy, 567-568, 687-688, 690
Solar thermal engine, 687-691
Sonar, 692-696; and radar, 823
Sones, F. Mason, 240
Sony Corporation, 165, 218-224, 539,
778, 781, 783-785, 788-789, 875-881
Spaeth, Mary, 459, 461
Spallanzani, Lazzaro, 54
Spangler, James Murray, 832
Spencer, Percy L., 502, 504
Sperry, Elmer Ambrose, 382, 384
Sputnik, 63-66, 446, 874
“Star Wars” (Strategic Defense
Initiative), 699
Staudinger, Hermann, 530
Stealth aircraft, 697-700
Steelmaking process, 701-708
Steenstrup, Christian, 289
Stewart, Alice, 823
Stewart, Edward J., 272
Stibitz, George, 828
Stine, Charles M. A., 529
STM. See Scanning tunneling microscope
Stockard, Charles, 549
Stokes, T. L., 394
Storax, 597
Strassmann, Fritz, 76
Strategic Defense Initiative, 416, 699
Strowger, Almon B., 751, 753
Styrene, 148-149, 597-598
Submarines; detection of, 692, 695, 823;
navigation, 382-385; nuclear, 98, 521;
weapons, 245-246
Sucaryl, 248
Suess, Theodor, 701
Sulfonamides, 24
Sullivan, Eugene G., 606
Sun, 514, 725; energy, 725; and nuclear
fusion, 511, 515, 567, 687; and
timekeeping, 80
Sun Power Company, 688
Supercomputer, 709-713
Supersonic passenger plane, 714-719
Surgery; and artificial blood, 39; and
artificial heart, 46, 48; and blood
transfusion, 113-117; and breast
cancer, 486-487, 489; cardiac, 499;
coronary artery bypass, 240-243;
and heart-lung machine, 394-397;
kidney-transplant, 61; laser eye,
468-472; laser vaporization, 472-476;
transplantation, 61
Sutherland, Ivan, 866, 868
Sveda, Michael, 67, 248
Svedberg, Theodor, 815
Swarts, Frédéric, 630
Swinton, Alan A. Campbell, 756
Sydnes, William L., 558
Synchrocyclotron, 720-723
Synthetic amino acid, 724-728
Synthetic DNA, 729-732
Synthetic RNA, 733-736
Syphilis, 24, 554-556, 673, 676, 744; test,
737-740; treatment of, 673-674, 676-
677
Szostak, Jack W., 41
Talking motion pictures, 741-745
Tarlton, Robert J., 208-209
Tassel, James Van, 576
Taylor, Frederick Winslow, 71
Taylor, William C., 606

Tee-Van, John, 100
Teflon, 746-750
Telecommunications Research
Establishment, 201
Telegraphy, radio, 616
Telephone; cellular, 172-176; longdistance,
482-485; rotary dial, 663-
667, 751, 774-776; touch-tone, 667,
774-777
Telephone switching, 751-755
Television, 756-760
Teller, Edward, 78, 412, 414, 416
Tesla, Nikola, 13, 832
Teutsch, Georges, 1
Tevatron accelerator, 761-764
Texas Instruments, 140, 153, 232-233,
419, 577-579, 787-788
Theiler, Max, 905
Thein, Swee Lay, 370
Thermal cracking process, 765-769
Thermionic valve, 564
Thomson Electron Tubes, 901
Thomson, Joseph John, 494, 496, 563-
564, 838
Thornycroft, John Isaac, 407, 409
Thornycroft, Oliver, 442
Tidal power plant, 770-773
Tiros 1, 887-890
Tiselius, Arne, 815
Tokyo Telecommunications
Engineering Company, 778, 780,
787, 875. See also Sony Corporation
Tomography, 168, 170
Topografiner, 679
Torpedo boat, 409
Touch-tone telephone, 667, 774-777
Townes, Charles Hard, 459
Townsend, John Sealy Edward, 365
Toyota Prius, 363
Transistor radio, 786-790
Transistors, 172, 229, 232, 390-391, 418-
419, 778-788, 875-876; invention of,
840
Traut, Herbert, 549
Tressler, Donald K., 343
Truman, Harry S., 78
Tsiolkovsky, Konstantin, 63, 65
Tuberculosis vaccine, 791-794
Tungsten filament, 795-798
Index / 935
Tuohy, Kevin, 235
Tupper, Earl S., 799, 803
Tupperware, 799-806
Turbojet, 807-810
Turing, Alan Mathison, 104, 200, 668
Turner, Ted, 208, 211
Tuskegee Airmen, 612
Typhus vaccine, 811-814
U2 spyplane, 245, 432
U-boats. See Submarines
Ulam, Stanislaw, 412, 414
Ultracentrifuge, 815-818
Ultramicroscope, 819-822
Ultrasound, 823-827
Unimate robots, 654-656
UNIVAC. See Universal Automatic
Computer
Universal Automatic Computer, 106,
315, 331, 348, 711, 828-831
Upatnieks, Juris, 402
Urey, Harold Clayton, 724
Uterine cancer, 549, 552
V-2 rocket, 65, 244, 659, 662, 871-874
Vaccines. See Polio vaccine;
Tuberculosis vaccine; Typhus
vaccine; Yellow fever vaccine
Vacuum cleaner, 832-836
Vacuum tubes, 339, 837-841; and
computers, 106, 201-202, 313-314;
and radar, 391; and radio, 478, 623;
and television, 783; thermionic
valve, 564; and transistors, 229, 391,
778-780, 786-787, 876. See also
Cathode-ray tubes
Vat dye, 842-845
VCR. See Videocassette recorder
Vectograph, 432
Veksler, Vladimir Iosifovich, 720
Velcro, 846-849
Vending machine slug rejector, 850-856
Videocassette recorder, 214, 218, 857-
860; and laservision, 465
Videodisc, 219
Vigneaud, Vincent du, 50
Virtual machine, 861-865
Virtual reality, 866-870
Vitaphone, 742
Vogel, Orville A., 638, 643

936 / Index
Volta, Alessandro, 355
Vonnegut, Bernard, 183
Vulcanization of rubber, 146, 149
Wadati, Kiyoo, 645
Waldeyer, Wilhelm von, 673
Walker, William H., 130
Walkman cassette player, 165, 784, 788,
875-882
Waller, Augustus D., 293
Warner Bros., 741-745
Warner, Albert, 741, 744
Warner, Harry, 741, 744
Warner, Jack, 741, 744
Warner, Samuel, 741, 744
Warren, Stafford L., 487
Washing machine, electric, 883-886
Washington, George, 289
Wassermann, August von, 676, 737
Watson, James D., 41, 177, 729, 733
Watson, Thomas A., 482
Watson, Thomas J., 394, 558
Watson, Thomas J., Jr., 386
Watson-Watt, Robert, 611
Weather; and astronomy, 609; cloud
seeding, 183-186; and rockets, 712
Weather satellite, 887-890
Wehnelt, Arthur, 837
Wells, H. G., 659
Westinghouse, George, 335
Westinghouse Company, 101, 440, 758-
759, 832
Wexler, Harry, 887
Whinfield, John R., 589
Whitaker, Martin D., 525
White, Philip Cleaver, 421
White Sands Missile Range, 873
Whitney, Eli, 71, 335
Whittle, Frank, 807
Wichterle, Otto, 235
Wigginton, Randy, 28
Wigner, Eugene, 525, 789
Wilkins, Arnold F., 611
Wilkins, Maurice H. F., 733
Wilkins, Robert Wallace, 634
Williams, Charles Greville, 146
Wilmut, Ian, 177-178
Wilson, Robert Rathbun, 761
Wilson, Victoria, 370
Wise, Brownie, 799
Wolf, Fred, 289-290
Woodrow, O. B., 883
World War I, and nitrates, 18
World War II; and Aqualung, 36;
atomic bomb, 84, 118, 521, 525-527,
697, 721; and computers, 92; spying,
34, 200, 202, 668; V-2 rocket, 65, 244,
659, 662, 871-874
Wouk, Victor, 360, 362
Wozniak, Stephen, 28, 30
Wright, Almroth, 555
Wright, Orville, 6-10, 658
Wright, Wilbur, 6-10, 335, 658
Wynn-Williams, C. E., 200
Xerography, 891-895
Xerox Corporation, 891-894
X-ray crystallography, 896-900
X-ray image intensifier, 901-904
X-ray mammography, 486-489
Yellow fever vaccine, 905-908
Yoshino, Hiroyuki, 360
Zaret, Milton M., 468
Zenith Radio Corporation, 209, 341
Zeppelin, Ferdinand von, 267-270
Ziegler, Karl, 593
Zinn, Walter Henry, 118
Zinsser, Hans, 811
Zippers, 846-847
Zoll, Paul Maurice, 545
Zsigmondy, Richard, 819, 821
Zweng, H. Christian, 468
Zworykin, Vladimir, 756, 758