Man's physical universe

xanabras

MACHINES HAVE RAISED LIVING-STANDARDS 311

In 1884 Charles A. Parsons invented a more efficient steam engine,

the steam turbine. Steam turbines are used in ocean liners and power

stations today. In one type of steam turbine the steam pushes curved

blades around on a number of wheels on the same shaft. The steam

strikes a row of blades on a wheel, then a row of stationary blades to

change its direction, and then a row of blades on a wheel again, until

the energy of the steam is about exhausted.

Rotary Motion Has Many Advantages over Reciprocating Motion.

In the reciprocating steam engine the piston moves back and forth,

coming to a dead stop between each change in direction of motion,

thus wasting energy and cutting down speed. The power-driven

circular saw saws wood much more rapidly than the ordinary reciprocating

handsaw of the carpenters. Similarly, the steam turbine is more

efficient and more speedy than the reciprocating steam engine. Vibrations

are cut down in rotary machines. For that reason a steam turbine

is sometimes preferred to a Diesel engine, which is a reciprocating

engine, for use in ocean liners. Rotary machines are much easier to

lubricate than are reciprocating engines; compare the ease of lubricating

an electric motor with the problem of lubricating an internalcombustion

engine.

Many inventions have represented rotary machines which would

replace reciprocating machines. Thus the oar was replaced by the

propeller,

the paddle by the paddle wheel, the broom by the carpet

sweeper, the carpenter's plane by the rotary plane, the sickle or scythe

by the lawn mower, and the file by the grinding wheel.

Technological Advancement Has Not Been Responsible for Unemployment.

The 1930 census shows there were 811,000 stenographers and typists

as compared with 615,000 ten years earlier.

In the same period, bookkeepers,

cashiers, and accountants increased from 735,000 to 931,000.

During this same period the manufacture of typewriters, cash registers,

adding and calculating machines, and numerous other business

machines increased.

Dial telephones increased from 27 per cent in

1921 to about 32 per

cent in 1930 in the Bell system; and yet telephone operators increased

from 190,000 in 1920 to 249,000 in 1930, and the number of telegraph

and telephone linemen almost doubled.

Railroad employment dropped by about 1,000,000 workers since

1920, but in 1935 there were 2,700,000 truck drivers, 153,000 bus

drivers, and 301,000 highway workers.

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