Crystal Palace International Electric Exhibition 1881-82

49 118 .—E. Barber Bernard, 122, Junction Road, N. Railway Passengers’ Safety Signal. Five operations are performed by one pull of the handle, which opens the communication with the next compartment, exhibits the “ disc” indicating the carriage, rings the bells in the driver’s and guard’s van, and in the carriage. Western Gallery. 119 .—Binko & Co., 12, Coleman Street, Bunhill Row, E.C. Bells and Indicators. West Corridor. 120 .—Geo. Gr. Blackwell, 26, Chapel Street, Liverpool. Electric Bells and Pushes in working order (various sizes). {See Advt., p. 126.) Southern Gallery. 121 .—Blakey, Emmott, & Co., Northern Telegraph Works, Halifax. Large collection of Switches; Morse Keys, mounted on ebonite; Warburton and Crossley’s Patent Bell Instru- ment; Warburton and Crossley’s Relays; Warburton’s Special Arms foi' Telegraph Poles; Warburton’s Signal Repeater, as used by the Lancashire and Yorkshire Railway Company; Warburton’s Transfer Switch; Trembling Bells ; Battery- Reversers and Terminals, with battery clamps of special form; Single Needle Block Instrument, as used on the Great Northern Railway; Railway and Colliery Bells; Press Buttons; Thief Detectors. Western Gallery and North Nave. 122 .—Edward B. Bright, C.E., 45, Gerrard Street, London. Street Fire Alarm, (adopted in London by the Metropolitan Board of Works), consisting of a set of street-posts and wall- boxes fixed at various points throughout the Palace, and c®n- nected by a wire with a set of alarm apparatus at the brigade station established at the Palace by the Metropolitan Fire Brigade. This system of fire alarm works on the principle of the electrical balance, and dispenses with all clockwoi’k and intricate mechanism. A small electro-magnetic coil of definite resistance is placed in each, street-post or wall-box, and is brought into circuit by pulling the handle. This increases the electrical resistance of the wire along the streets, which had been previously balanced by a cor- responding resistance in a rheostat at the fire brigade station and the needle of a galvanometer relay is deflected, ringing an alarm until the commutator-handle on being turned inserts an additional electrical resistance, equivalent to that of the alarm- post, whence the call has emanated. The locality of the post is shown on the dial of the commutator. If the conducting-wire is out of order, attention is immediately called to it by the station apparatus ringing, on the electrical balance being disturbed. Self-acting Fire Alarm for buildings, illustrated by a working model, heat detectoi’S, localisers, and commutators. In applying this apparatus the small heat detecting boxes (about 1 in. square) are placed on the cornice or ceiling of each, room protected. A bi-metallic spring in each box is expanded on. any undue heat