120 TRANSACTIONS OF THE ROYAL CANADIAN INSTITUTE [VOL. XI. 
submarine boat before the Directory, but it was not till three years later, 
when he offered his design to Bonaparte, who was then First Consul, 
that his plans were seriously considered. Bonaparte saw the possi- 
bilities of the new weapon and appointed a Committee consisting of 
Volney, Monge, and Laplace, who gave a favorable report. A sum of 
10,000 francs was appropriated for the purpose and an experimental 
boat was constructed. The shell plating of this boat was of brass with 
iron frames. The boat was propelled by hand-driven screws. Fulton 
descended to a depth of 25 ft. and remained under water for more than 
four hours. He carried a store of compressed air in a tank for renewal of 
the air. He blew up a small vessel in the harbor of Brest, attaching a 
mine to her bottom. In spite of the relative success of the experiments, 
Napoleon realised that the speed, which was only two knots, was too 
small for military purposes, and nothing further was done. 
During the Civil War in America a number of so-called ‘‘ Davids”’ 
were built by the Confederates. Although referred to as submarine 
boats, they were probably most of them surface boats, going awash 
with very little freeboard, showing practically only a cupola above the 
surface. Some of them were designed for diving, but it is not known 
that any of them operated successfully under water. Most of the Davids 
were constructed of iron plates and some were propelled by steam- 
power. They were built in haste with limited resources and necessarily 
primitive in construction. They are of interest chiefly because they 
were actually employed in war and because one of them, a hand-driven 
boat, succeeded in blowing up a Northern ship, the Housatonic. 
At the same time the French Government built a submarine boat, 
the Plongeur, which was launched at Rochefort in 1863. The Plongeur 
was of about 450 tons displacement, much larger than any boat built 
heretofore and thereafter up till a few years ago. The general shape 
was not unlike that of an ordinary torpedo boat, and it carried a super- 
structure on top in which was housed a detachable boat to be used in 
case of emergency. The hull was built of iron plating stiffened by 
frames. Ballast tanks were fitted for changing the displacement, and 
the depth was to be kept by two regulating cylinders which produced 
variations in the force of buoyancy. There were also vertical and 
horizontal rudders. The boat was propelled by an engine driven by 
compressed air, whence a very large store of compressed air at a pressure 
of 12 atmospheres was carried. The engine was of 80 horse-power and 
operated a propeller which gave the boat a speed of about 5 kts. on the 
surface. Le Plongeur went down to depths of from 30 to 4o ft., she 
could slide along an even bottom without difficulty, but steering in the 
vertical plane caused great difficulties. She was the best designed 
