BUILT-UP GUNS. Recently invented guns of great strength, specially adapted to meet the requirements of rifled artillery and of the attack of iron plating. They are usually composed of an inner core or barrel (which may be of coiled and welded iron, but is now generally preferred of tough steel), with a breech-piece, trunnion-piece, and various outer strengthening hoops or coils of wrought iron, shrunk or otherwise forced on; having their parts put together at such predetermined relative tensions, as to support one another under the shock of explosion, and thereby avoiding the faults of solid cast or forged guns, whereof the inner parts are liable to be destroyed before the outer can take their share of the strain. The first practical example of the method was afforded by the Armstrong gun, the "building up" which obtained in ancient days, before the casting of solid guns, having been apparently resorted to as an easy means of producing large masses of metal, without realizing the principle of the mutual support of the various parts. BUIRAN. A Gaelic word signifying the sea coming in, with a noise as of the roar of a bull. BULCH, TO. To bilge a ship. BULGE. (_See_ BILGE.) That part of the ship she bears upon when on the ground. BULGE-WAYS. Otherwise _bilge-ways_ (which see). BULK. In bulk; things stowed without cases or packages. (_See_ BULK-HEAD and LADEN IN BULK.) BULKER. A person employed to measure goods, and ascertain the amount of freight with which they are chargeable. BULK-HEAD, THE. Afore, is the partition between the forecastle and gratings in the head, and in which are the chase-ports. BULK-HEADS. Partitions built up in several parts of a ship, to form and separate the various cabins from each other. Some are particularly strong, as those in the hold, which are mostly built with rabbeted or cyphered plank; others are light, and removable at pleasure. Indeed the word is applied to any division made with boards, to separate one portion of the 'tween decks from another. BULK OF A SHIP. Implies the whole cargo when stowed in the hold. BULL. An old male whale. Also, a small keg; also the weak grog made by pouring water into a spirit-cask nearly empty. BULL-DANCE. At sea it is performed by men only, when without women. It is sometimes called a stag-dance. BULL-DOG, OR MUZZLED BULL-DOG. The great gun which stands "housed" in the officer's ward-room cabin. General term for main-deck guns. BULLETIN. Any official account of a public transaction. BULLET-MOULD. An implement for casting bullets. BULLETS. Leaden balls with which all kinds of fire-arms are loaded. BULL-HEAD, OR BULL-JUB. A name of the fish called miller's thumb (_Cottus gobio_). BULLOCK-BLOCKS. Blocks secured under the top-mast trestle-trees, which receive the top-sail ties through them, in order to increase the mechanical power used in hoisting them up. BULLOCK-SLINGS. Used to hoist in live bullocks.