The Locomotive - Lighthouse Survival Blog

1901.
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THE LOCOMOTIVE. 121
devised and tried with this object in view, it was concluded that the cathode rays consist
of minute particles of matter flying- about like tiny comets. Professor Thomson
does not question this conclusion at all; but he believes that we cannot admit that the
particles in question arc either molecules or dissociated atoms, as was universally sup-
posed until a few months ago. He devised and carried out some very ingenious experiments
which indicated that the particles composing the cathode rays are either only one
one-thousandth as big as hydrogen atoms, or else that they are charged with a thousand
times as much electricity as we have heretofore supposed a hydrogen atom could hold.
(This much of his theory is pretty soundly established.) He next proceeded to devise a
method for distinguishing which of these two alternatives is correct. His method of
discriminating between the two is not quite as convincing as the rest of his argument;
but his conclusion is, as we have indicated, that we must admit the existence of particles
only one one-thousandth as big as a hydrogen molecule.
If further experiments bear out Professor Thomson's conclusions, we shall certainly
have to recast all our ideas of molecular physics; and no man can yet see where the
new notions may lead us to.
If anyone should ask " what good" all this is, we can oidy answer that it certainly
does not promise to make sheep fatter, nor to reduce the price of potatoes. But any
enlightenment that we can get on the constitution of the universe is surely welcome,
and the strict utilitarian will do well to remember that Faraday's apparently trifling and
"useless" experiments with wires and magnets have now, half a century later, made
the trolley-car possible.
Economy in Marine Engineering*.
A lecture delivered before the students of Sibley College, Cornell University, by
W. M. McParland, upon the progress of economy in marine engineering, has recently
been published in the Sibley Journal of Engineering, and as a number of interesting and
valuable points in the history of steam engineering were brought out by the lecturer, we
have made copious extracts from his remarks.
Starting with the Clermont, the first really successful steamer, and taking up in
order the Savannah, Great Eastern, and other noted craft, the speaker said that it was
impossible to obtain any reliable figures about the steam consumption of such early ves-
sels. One book, printed in 1825, makes the statement that the coal per horse power at
that period on steamers was ten pounds, but the method of computing the horse power
is not stated, and, from the general method used in the book, it is doubtful if this figure
is at all accurate. When we consider the conditions under which machinery was oper-
ated, however, ten pounds per horse power does not seem incredible. The steam pres-
sure carried was very low, frequently not more than five to ten pounds above the atmos-
phere, the engines were very slow for driving the paddle wheels, the cylinders were
unjacketed, and the steam was used almost entirely without expansion.
The first steam war vessel of our navy, the Fulton, built in 1837, had for her chief
engineer Charles H. Haswell, the author of " Haswell's Pocket Book," and an extract
from her steam log for a portion of January, 1838, shows that the maximum steam pres-
sure was eleven pounds, the vacuum twenty-four inches, and the maximum revolutions
per minute, eighteen.
As already stated, the early steamers were all driven by paddle wheels, and although
a small launch was driven by a screw propeller as early as 1804, the propeller did not
attract serious attention for driving until about 1840. The screw propeller naturally