
ON THE FORM OF SHIPS. 113 
such was the problem hitherto the least resolved, and always one of the most 
important which these experiments were intended to investigate. 
There were also two phases in which the problem presented itself, the 
scientific and the practical view of the subject: there were therefore two 
classes of experiments—those designed to advance our knowledge of the laws 
of hydrodynamics which govern the phenomena of resistance of fluids, and the 
other the experiments serving as a basis to the operations of the practical 
construction of ships, the Experimenta Lucifera and the Experimenta Fruc- 
tifera of Lord Bacon. 
Many experiments had formerly been made on this subject, but we had at 
that time so imperfect a system of hydrodynamics, that the conclusions 
drawn from them could not be relied on with confidence in the applications 
to be made on a large scale by the practical man. The Academy of Sci- 
ences had made a series of such experiments at large expense, defrayed by 
the French government. Colonel Beaufoy in our own country had made an 
important series of such experiments, at an expense of £30,000, but these 
were of comparatively little value for the same reason, viz. that the forms did 
not comprehend such forms as were actually required for the purposes of naval 
construction, and because the state of science was not such as to enable us, 
from the resistance of one form, to deduce with certainty that of another. 
One experiment of Colonel Beaufoy was of value, as it told us the resistance 
produced by the adhesion of water to the surface of a body independent of 
form, at various velocities. But the others were made on bodies not ana- 
logous to the forms of ships, and many of them on forms moved through the 
water far below the surface, and so suited to the construction of fishes or 
submarine navigation, but not for the purpose of sailing on the surface. For 
the purpose of giving practical value to the present series, experiments had 
been made on many different scales of magnitude, some in narrow channels, 
others in large canals, and finally on the open sea. Some were made on 
models of 3 feet in length, others of 10 feet; some on vessels 25 feet long, 
75 feet long, and some on vessels 200 feet long and nearly 2000 tons capa- 
city. Thus it was trusted that the scale of the experiments was such as to 
give confidence in the results. Next, as regards the forms of vessels made 
the subject of experiment, they were similar to those required for the prac- 
tical purposes of construction. One class consisted of such forms as were 
required for steam navigation ; plans of steam ships of the best construction, 
and others of worse forms, were accurately laid down on the same scale, in 
the same way and with the same accuracy of proportion as if they had been 
for actual construction, and along with these were some of new forms. A 
given form having been found to be a good one, was then varied by length- 
ening, first in one manner, then in another; now in the middle, now at the 
rear, now at the entrance, and so on, to discover the best mode of improving 
a given good form. In sailing vessels some of the celebrated Chapman’s best 
forms were taken and treated in a similar manner, and along with them were 
compared the common forms of merchantmen and other ships. The class of 
fast-sailing yachts and cutters was treated in the same way, by taking some 
of the best known forms and determining by experiment the effects produced 
by lengthening and shortening them, making them fuller here, and finer there, 
and so ascertaining with accuracy the effect of each alteration of form on the 
great object of inquiry, namely, the determination in given circumstances of 
the method of giving such a form to a ship as shall enable her to pass through 
the water with the least resistance, the greatest velocity, and of course the 
smallest expenditure of force, power, and money. To these were added a 
number of theoretical and geometrical forms. 
1843. I 
