ed guaranteed, but of the better part of
a knot in excess of that speed, was triumphant testimony to the skill
and care brought to bear upon the undertaking. In this case, at least,
the result was not one due to a previous course of "trial and error"
with actual ships, but was distinctly due to superior practical skill,
backed and enhanced by knowledge and use of specialized branches in
the science of marine architecture. Messrs. Denny are the only firm of
private shipbuilders possessing an experimental tank for recording the
speed and resistance of ships by means of miniature reproductions of
the actual vessels, and to this fact may safely be ascribed their
confidence in guaranteeing, and their success in obtaining, a speed so
remarkable in itself and so much in excess of anything they had
previously had to do with. Confirmatory evidence of their success with
the Belgian steamers is afforded by the fact that they have recently
been instructed to build for service between Stranraer and Larne a
paddle steamer guaranteed to steam 19 knots, and have had inquiries as
to other high speed vessels.

In estimating the power required for vessels of unusual types or of
abnormal speed, where empirical formulae do not apply, and where data
for previous ships are not available, the system of experimenting with
models is the only trustworthy expedient. In the case of the Czar's
extraordinary yacht, the Livadia, already referred to, it may be
remembered that previous to the work of construction being proceeded
with, experiments were made with a small model of the vessel by the
late Dr. Tideman, at the government tank at Amsterdam. On the strength
of the data so obtained, coupled with the results of trials made with
a miniature of the actual vessel on Loch Lomond, those responsible for
her stipulated speed were satisfied that it could be attained. The
actual results amply justified the reliance placed upon such
experiments.

The design of many of her Majesty's ships has been altered after
trials with their models. This was notably the case in connection with
the design of the Medway class of river gunboats. The Admiralty
constructors at first determined to make them 110 ft. long, by only 26
ft. in breadth. A doubt arising in their minds, the matter was
referred to the late Mr. Froude, who had models made of various
breadths, with which he experimented. The results satisfied the
Admiralty officers that a substantial gain, rather than