was desired to ascertain.
In 1839, Thornthwaite (England) adopted a waist-belt of india-rubber cloth, to which was connected a small, strong copper vessel charged with highly compressed air. The belt is put on in a collapsed state, and the diver descends; but when he wishes to rise, by a valve he allows the compressed air to fill the belt, which increases his levity and assists his ascent.
The armor used by Mr. Dean in 1834, when he descended to the wreck of the Royal George (sunk off Spithead, August 28, 1782), was composed of india-rubber, made perfectly water-tight, and having a metallic helmet which rested on the shoulders and admitted free motion of the head.
Three glass windows admitted light and allowed the diver to examine the remains of the ship.
A flexible tube was connected to an air-pump above, and admitted air to the helmet.
A sinking-weight of 90 pounds was attached to his person.
A race in submarine armor took place in Boston harbor on the 4th of July, 1868.
fted by the guide-rollers, and the process is repeated.
The cards are finished and made true by grinding.
(See card-grinding machine.) These wire brushes are termed cards, and such fillets form the clothing of the drums, cylinders, or strips to which they are fastened.
（Nautical.) The operation of exposing a part of a ship's bottom by a purchase applied to the masts to tilt them laterally from the perpendicular.
It was careening that upset the Royal George in 1782 at Spithead: —
They Had made the vessel heel, And laid her on her side.
（Printing.) A mark ( ⁁ ) indicating an insertion; interlinear or marginal.
（Nautical.) An implement like a lifting-jack, but sometimes used upon its side for stowing heavy cargo.
（Nautical.) An opening in the side of vessels having two or more decks, through which the lading is received and delivered.
It is closed by a shutter; and made water-tight before
; the other end is the head.
（Carpentry.) The lower end or foot of a rafter where it rests on the wall or plate.
（Fire-arms.) The upper end of the butt-end of a musket when in firing position.
The tail of a gun-lock hammer.
3. A lean or inclination.
（Nautical.) a. The inclination laterally of a vessel as she careens under a press of sail.
Allowance for the heel is made in laying guns, a pendulum being used for the purpose.
In careening the Royal George, 120 guns, at Spithead, 1782, to get at a water-pipe which discharged below the water-line, the vessel was sunk at her moorings.
They made the vessel heel And laid her on her side.
b. Said of a ship when deep in the water aft. By the heel, in contradistinction to by the head.
（Shoemaking.) A set of lifts fastened together in readiness for attachment to a boot.
A blank heel.
Heel-breast′-- ing ma-chine′.
A machine for cutting down the straight front
lerophon is 6 inches, and that of the Hercules, as already stated, 9 inches. The French have increased the thickness of their plating to 15 centimetres, about 6 inches; and the Marengo and Ocean have plating 20 centimetres, or nearly 9 inches, in thickness.
Plates for experimental purposes have been rolled 15 inches thick, and it is claimed that plates of sound and uniform quality can be rolled 10 inches thick.
To resist the attacks of iron-clads the British government is erecting at Spithead two forts, plated with 15-inch iron.
Each fort is 700 feet in circumference, 230 feet in height, and is armed with two tiers of guns, one consisting of twenty-four 600-pounders, and the other of twenty-five 400-pounders.
The two will command the only deep channel leading from the sea to Portsmouth Harbor.
The estimated cost of each fort is about £ 1,000,000 sterling.
Fig. 2703 shows broadside views of a number of English iron-clads, and is introduced to illustrate
Rockets of large size, guided by a tube projecting from the vessel, have been tried, but without very flattering prospects of success.
See submarine boat; submarine gun; torpedo.
（Hydraulic Engineering.) A means for the removal of submerged rocks, shoals, sunken vessels, or other impediments to navigation.
The first effort in this direction was probably that of Colonel Pasley, about 1841, in blowing up the wreck of the Royal George, sunk at Spithead, England, in 1782.
Fig. 6021 illustrates some of the operations for the removal of the submarine obstacles to navigation which formerly rendered that part of the East River known as Hellgate so dangerous to navigation in Long Island Sound.
The principal of these were Pot Rock, on which the British frigate Hussar was wrecked at the close of the Revolutionary War, occasioning the loss of many lives and a large amount of treasure; Drake Rock; Holmes' Rock; the Frying Pan: and Way's Reef.