s, 5 large bomb-ketches,
and 300 large boats to be employed in landing the troops as soon as a
breach should be made--besides which, there were 10 large floating
batteries, the invention of the Chevalier D'Arzon, a French engineer of
great repute, on such a principle that they would not, he believed, be
sunk or set on fire by shot. It was said that no less than 1200 pieces
of heavy ordnance had been accumulated before the place, with 83,000
barrels of gunpowder, and shot, shells, military stores, and provisions
in the same proportion. The chief reliance of the besiegers was,
however, placed on the floating batteries. They were built of
extraordinary thickness, and so fortified that they were proof from all
external, as well as internal, violence. To prevent their being set on
fire, a strong case was formed of timber and cork, a long time soaked in
water, and enclosing a large body of wet sand; the whole being of such
thickness and density that no cannon-ball could penetrate within two
feet of the inner partition.

For this purpose, ten large ships, from 600 to 1400 tons burden, had
been cut-down, and 200,000 cubic feet of timber worked in their
construction. To protect them from bombs, and the men at the batteries
from grape, or descending shot, a hanging roof was contrived; which was
worked up and down by springs. The roof was composed of a strong
rope-work netting, laid over with a thick covering of wet hides, while
its sloping position was calculated to prevent shells from lodging, and
to throw them off into the sea before they could burst. To render the
fire of these batteries the more rapid, a kind of match had been
contrived, so to be placed that all the guns in the battery could go off
at the same instant. To defend them from red-hot shot, with which the
fortress was supplied, the newest part of the plan was that by which
water could be carried in every direction to neutralise its effect. In
imitation of the circulation of the blood, a variety of pipes and canals
perforated all the solid workmanship in such a manner that a continued
succession of water could be conveyed to every part of the structure, a
number of pumps being adapted to afford an unlimited supply. It was
thus believed that these terrible machines, capable of inflicting
destruction, would themselves be invulnerable. The largest carried 21
guns, and their complement of men was 36 for each gun in use, exclusive
of officers and mariners for