BALL-CLAY. Adhesive strong bottom, brought up by the flukes of the anchors in massy lumps. BALLISTA. An ancient military engine, like an enormous cross-bow, for throwing stones, darts, and javelins against the enemy with rapidity and violence. Also, the name of the geometrical cross called Jacob's staff. BALLISTER. A cross-bow man. BALLISTIC PENDULUM. An instrument for determining the velocity of projectiles. The original pendulum was of very massive construction, the arc through which it receded when impinged on by the projectile, taking into account their respective weights, afforded, with considerable calculation, a measure of the velocity of impact. Latterly the electro-ballistic pendulum, which by means of electric currents is made to register with very great accuracy the time occupied by the projectile in passing over a measured space, has superseded it, as being more accurate, less cumbrous, and less laborious in its accompanying calculations. BALLIUM. A plot of ground in ancient fortifications: called also _baiky_. BALLOCH. Gaelic for the discharge of a river into a lake. BALLOEN. A Siamese decorated state-galley, imitating a sea-monster, with from seventy to a hundred oars of a side. BALL-OFF, TO. To twist rope-yarns into balls, with a running end in the heart for making spun-yarn. BALLOON-FISH (_Tetraodon_). A plectognathous fish, covered with spines, which has the power of inflating its body till it becomes almost globular. BALLOW. Deep water inside a shoal or bar. BALL-STELL. The geometrical instrument named _della stella_. BALLY. A Teutonic word for inclosure, now prefixed to many sea-ports in Ireland, as Bally-castle, Bally-haven, Bally-shannon, and Bally-water. BALSA, OR BALZA. A South American tree, very porous, which grows to an immense height in a few years, and is almost as light as cork. Hence the balsa-wood is used for the surf-boat called _balsa_. (_See_ JANGADA.) BALTHEUS ORIONIS. The three bright stars constituting Orion's Belt. BALUSTERS. The ornamental pillars or pilasters of the balcony or galleries in the sterns of ships, dividing the ward-room deck from the one above. BAMBA. A commercial shell of value on the Gold Coast of Africa and below it. BAMBO. An East Indian measure of five English pints. BAMBOO (_Bambusa arundinacea_). A magnificent articulated cane, which holds a conspicuous rank in the tropics from its rapid growth and almost universal properties:--the succulent buds are eaten fresh and the young stems make excellent preserves. The large stems are useful in agricultural and domestic implements; also in building both houses and ships; in making baskets, cages, hats, and furniture, besides sails, paper, and in various departments of the Indian _materia medica_. BAMBOOZLE, TO. To decoy the enemy by hoisting false colours.