W. Bayley (1824).
2. An animated picture machine for screen projection; a cinematograph (which see).
Bi"plane (?), n. [Pref. bi- + plane.] (Aëronautics) An aëroplane with two main supporting surfaces one above the other.
Bi"plane, a. (Aëronautics) Having, or consisting of, two superposed planes, aërocurves, or the like; of or pertaining to a biplane; as, a biplane rudder.
Bi"prism (?), n. [Pref. bi- + prism.] 1. A prism whose refracting angle is very nearly 180 degrees.
2. A combination of two short rectangular glass prisms cemented together at their diagonal faces so as to form a cube; -- called also optical cube. It is used in one form of photometer.