The Locomotive - Lighthouse Survival Blog

126 THE LOCOMOTIVE. [August,
such fight against the triple expansion engine as there had been against the compound,
and in a very few years all new engines were of this type, with pressures at first of one
hundred and fifty to one hundred and sixty pounds. With ordinary boilers of thor-
oughly good design, the coal expenditure in regular working at sea was probably about
two pounds per horse power hour or slightly less.
The late Mr. Thomas Mudd, a very progressive engineer, who was the head of a
works in England which built machinery for cargo vessels, developed a type of machinery
of about eight hundred horse power which attained probably the greatest economy
that any marine triple expansion engine reached. One of his vessels, the Iona, was
given a very careful test by a committee of the Institute of Mechanical Engineers in
Great Britain, where a horse power was obtained for about 15 pounds of steam and 1.46
pounds of coal per horse power hour. As will be seen, the steam consumption was very
low, and the unusually low coal consumption was brought about by a remarkably eco-
nomical boiler, which had a ratio of heating to grate surface of 75 and used assisted
draft.
An extension of the multiple expansion principle has given us the quadruple expan-
sion engine, where there are four separate expansions. A number of the very laro-e
trans-Atlantic steamers, including our own St. Louis and St. Paul, have engines of this
kind, with two high pressure and two low pressure cylinders, and a single first and second
intermediate cylinder. In view of previous experience the steam pressure, of course,
was raised to about two hundred pounds.
Mr. Mudd, shortly before he died, built a five-cylinder quadruple expansion engine
which secured a coal expenditure of about 1.2 pounds of coal per horse power hour.
Since his death his firm have recently built machinery for a vessel called Inchdune, which
has secured the phenomenal result of a horse power hour for .97 of a pound of coal.
The engines are quadruple expansion with five cylinders, carrying a steam pressure of
two hundred and sixty-seven pounds per square inch, and with the steam superheated
to a temperature of about 500 degrees Fahrenheit. The cylinders are carefully jacketed
and the feed water is also heated to a temperature of about 370 degrees before entering
the boiler.— Steam Engineering.
TnE Causes op Yellow Fever and Cancer. — What can be accomplished by
properly-directed medical research is proved by two advances of extraordinary import-
ance made recently by American students. These are the discovery of the probable
causes of yellow fever and of cancer. In the July issue of the Popular Science Monthly
Surgeon-General Sternberg describes the experiments made under his direction by a
board of army surgeons in Havana. In heroic self-sacrifice and triumphant achievement
these experiments have surely an absorbing interest, surpassing any fiction. Although
the yellow fever parasite has not been seen, its existence seems as certain as that of the
malaria parasite. We now know that yellow fever is not directly contagious, but is
transmitted by a special kind of mosquito, and, probably, only in this way. If we ex-
terminate certain kinds of mosquitoes, or prevent them from biting those diseased, or
from biting those who are well, two of the most dreadful diseases — yellow fever and
malaria — will be exterminated. The cost in money and life of the Spanish-American
War has been more than repaid to society by the services of the medical army officers.
Science is often said to be cosmopolitan, but men of science owe allegiance to their coun-
try, and there is every reason to rejoice that it is also to an American that we owe the
discovery of the probable cause of cancer. Dr. Harvey R. Gaylord, working in the New
York State Pathological Laboratory, at Buffalo, has been able to cultivate the organisms