_Kite._—An elongated form of captive balloon, fitted with tail appendages to keep it headed into the wind, and deriving increased lift due to its axis being inclined to the wind. _Pilot._—A small spherical balloon sent up to show the direction of the wind. _Sounding._—A small spherical balloon sent aloft without passengers but with registering meteorological instruments. BALLOON BED: A mooring place on the ground for a captive balloon. BALLOON CLOTH: The cloth, usually cotton, of which balloon fabrics are made. BALLOON FABRIC: The finished material, usually rubberized, of which balloon envelopes are made. BANK: To incline an airplane laterally—i.e., to roll it about the longitudinal axis. Right bank is to incline the airplane with the right wing down. Also used as a noun to describe the position of an airplane when its lateral axis is inclined to the horizontal. BANK, ANGLE OF: The angle through which an aircraft must be rotated about its longitudinal axis in order to bring its lateral axis into the horizontal plane. BAROGRAPH: An instrument used to record variations in barometric pressure. In aeronautics the charts on which the records are made indicate altitudes directly instead of barometric pressures. BASKET: The car suspended beneath a balloon, for passengers, ballast, etc. BIPLANE: A form of airplane in which the main supporting surface is divided into two parts, one above the other. BODY OF AN AIRPLANE: See Fuselage and Nacelle. BONNET: The appliance, having the form of a parasol, which protects the valve of a spherical balloon against rain. BRIDLE: The system of attachment of cable to a balloon, including lines to the suspension band. BULL’S-EYES: Small rings of wood, metal, etc., forming part of balloon rigging, used for connection or adjustment of ropes. BURBLE POINT: See Angle, critical. CABANE: A pyramidal framework upon the wing of an airplane, to which stays, etc., are secured. CAMBER: The convexity or rise of the curve of an aerofoil from its chord, usually expressed as the ratio of the maximum departure of the curve from the chord to the length of the chord. “Top camber” refers to the top surface of an aerofoil, and “bottom camber” to the bottom surface; “mean camber” is the mean of these two. CAPACITY: See Load. The cubic contents of a balloon. CEILING: _Service._—The height above sea level at which a given aircraft ceases to rise at a rate higher than a small specified one, say 100 feet per minute. This specified rate may be different in the services of different countries. _Absolute._—The maximum height above sea level to which a given aircraft can rise. _Theoretical._—The limiting height to which a given aircraft can rise determined by computations of performance, based upon the drawings and wind tunnel data.