Handbook of projection for theatre managers and motion picture projectionists ([1922])

896 HANDBOOK OF PROJECTION FOR the best, with the buzzer as second. The bell should never be used. A buzzer is merely an electric bell without the bell part. What is known commercially as the dry battery is best for theatre work. Wet batteries are very effective, and very cheap in operation, but they are liable to freze in winter and thus cause a lot of trouble. The dry battery is cheap and effective. For wiring bells No. 18 ordinary cotton covered bell wire is 173 — FT 3 * \ i v^y 01 #FU A ^-^ 1 1 ! W — r -5 T 1 '"J 1 — 1 1 L x* — x •—i Ur ^V, I 1 -'J B£LL L *\ \^"~"C V ° 1 ' I • J c c * ^^__/ ' ?!?£ '' FHR cc Figure 368. plenty good enough, unless the circuit be a very long one, in which case No. 16 might be used. This holds good, except in very wet places, where it is better to use rubber covered wires, supported upon porcelain insulators. In putting up bell wires they may be gathered together in a cable and held to the wall with a wooden cleat. They may be run singly around picture molding, being held thereto by small iron staples, but where this is done a staple should never be driven over two wires, since it is likely to cut through the insulation and short-circuit the bell, the battery or both. Never drive a staple over two wires. Hold each wire with its own staples. A short circuit may cause your bell to ring all the time or not ring at all, according to its location. If on the two wires leading to the push-button the bell will ring continuously until the battery is worn out. If on the wire running from bell to battery and the wire running from button to bell the bell will not ring at all. Joints in the wire should be made in the usual way (see wire