among builders, an iron fastening fixed to doors and windows. They are generally distinguished into three kinds, viz. plate, round, and spring bolts.

Bolts in gunnery are of several sorts; as, 1. Tramfum bolts, that go between the cheeks of a gun-carriage, to strengthen the tramfums. 2. Prife-bolts, the large knobs of iron on the cheeks of a carriage, which keep the hand-spike from sliding when it is poising up the breech of a piece. 3. Traverfe-bolts, the two short bolts that being put one in each end of a mortar-carriage, serve to traverse her. 4. Bracket-bolts, the bolts that go through the cheeks of a mortar, and by the help of quoins keep her fixed at the given elevation. And, 5. Bed-bolts, the four bolts that fasten the brackets of a mortar to the bed.

Bolts in a ship are iron pins, of which there are several sorts, according to their different makes and uses. Such are drive-bolts, used to drive out others. Ray-bolts, with jags or bars on each side, to keep them from flying out of their holes. Clench-bolts, which are clenched with riveting hammers. Forelock-bolts, which have at the end a forelock of iron driven in, to keep them from starting back. Set-bolts, used for forcing the planks, and bringing them close together. Fend or fender-bolts, made with long and thick heads, and struck into the uttermost bends of the ship, to save her sides from bruises. And ring-bolts, used for bringing to of the planks, and those parts whereto are fastened the breeches and tackles of the guns.

Bolt of canvas, in commerce, the quantity of twenty-eight ells.

Bolt-rope. See Rope.