The Locomotive - Lighthouse Survival Blog

124 THE LOCOMOTIVE. [August,
knots, and the maximum speed for any one hour 17.75 knots. This was a speed greater
by at least four knots than that of any other vessel then afloat, and it is to be noted,
moreover, that the performance was at sea in the winter and under rather adverse con-
ditions. Indeed, the trial was terminated much earlier than had been intended on
account of a severe gale. The steam pressnre carried was thirty-two pounds above the
atmosphere, and the coal consumption was 3.1o pounds per horse power hour. We
should doubtless be not far wrong in assuming that the figures just given represent
about the best economy in simple engines in regular performance at sea.
During the period when Mr. Isherwood was engineer-in-chief of the navy he conducted
numerous experiments looking to increased economy, among which were some
including superheated steam, and, although these promised an increase of economy,
there were practical objections, on account of the speedy deterioration of the superheat-
ing apparatus, which prevented the adoption of this device.
During the '60's British marine engine builders had been developing the compound
engine, and by the early '70's it had become universal; steam pressures had risen to
sixty pounds and rotational speeds had increased. The engineer-in-chief who had suc-
ceeded Mr. Isherwood, Mr. J. W. King, after a visit to Europe in 1871, reported to the
Navy Department on the general adoption of compound engines in merchant steamers,
and also their experimental adoption in the British Navy, and he recommended that all
new machinery for our naval vessels should be of the compound type. In a later report
printed in 1877, after he had spent more than a year in Europe, he winds up a discus-
sion of the compound engine by saying: "In the face of these facts, further discussion
on the subject of adopting the compound engine for the vessels of our own navy is as
useless as would be a discussion of the relative merits of the screw propeller and paddle-
wheel for ships of war."
At that time about fifteen vessels in our own navy had been provided with compound
engines, and these remarks of Mr. King were not for the purpose of stimulating
engineers to progress, but to combat a most violent opposition on the part of many of
the deck officers in the navy who feared that the high pressures used with the compound
engine would lead to disastrous boiler explosions. As showing the intense oppo-
sition to increased steam pressure, an ordnance expert in the United States Navy said
that the boilers filled with this high pressure steam were equivalent to a magazine con-
taining so much gunpowder. At this time many naval officers still regarded the steam
engine as a disagreeable necessity on board ship, and encouraged in every way the use
of sail power when at sea.
The adoption of the compound engine was not nearly so rapid as that of the next
great step in marine engineering progress, and there were many who fought hard for
the retention of the simple engine. This was helped to a certain extent by the influence
of such great names as that of Professor Bankine, who proved mathematically that as
far as expansion itself was concerned there was'no advantage in using two cylinders of
different diameters instead of having the expansion occur in a single cylinder. I believe
no one would now maintain this view, for we understand much more about the effects
of condensation and of the desirability of limiting the range of temperature in a single
cylinder. It is possibly true that with unusual care in design and by using superheated
steam, steam jackets, etc., a single cylinder engine could be made to give as great
economy as an ordinary compound engine, but, under exactly the same conditions of
working, a compound engine would show a marked economy.
Some very interesting experiments were conducted by Messrs. Loring and Emery
on some revenue cutter vessels which were alike in every respect except the engines;