Stone-ves′sel.
The breakwater of
Cherbourg, France, was commenced in 1786, and was never completed according to the original design by De Cessart, but during the nine following years, 100,000,000 cubic feet of stone had been deposited in and around the 18 timber cones which formed the nuclei for the stone piles.
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De Cessart's stone-boat. |
De Cessart's machine for throwing large stones into the sea consisted of a pontoon carrying an inclined plane made at an angle of 22°. The deck had a level platform 6 feet in width, to carry the stone.
In the floor of the platform were 3 rollers, 6 inches in diameter, and hooped with iron.
A gib, moving on a pivot and furnished with hoisting-tackle, was employed to hoist the stones from the lighter which carried them to the spot.
Two wheels and axles worked the rope.
The wheels were 12 feet in diameter, the axles 1.
Iron grapplers and chains first lifted the stone from the lighter, and when the necessary hight was obtained, the gib was swung back into the position shown in dotted lines.
By loosening the tackle a little, the stone was deposited on the platform rollers, along which it traveled until it reached the discharging chute, which precipitated it into the sea.
In transporting and depositing the stones used in making the
Plymouth Breakwater, vessels were employed having a pair of longitudinal tracks on each side of the ship, on each deck.
On these tracks were trucks which held the stone, which were dumped at the stern, to which the trucks were conducted, one at a time, and tilted by tackle.
At the stern of the boat was an inclined plane, by which the loaded trucks reached the lower deck, and another inclined plane led from the upper deck to the opening in the stern, which was exposed when the shutters were lowered These shutters were supported by chains, and formed chutes.
