BRITISH AUTOMATIC FIRE ALARM.
Consul Mahin, of Nottingham, gives the following account of a recently invented British automatic fire alarm: “A new automatic fire alarm was tested in this town this week. In a large room of a hotel, where three of the alarms, small instruments, were attached to the ceiling, a quantity of waste on a tray was saturated with methylated spirit and set on fire. In twelve seconds a gong attached by electric wires to the instruments on the ceiling sounded an alarm. Only the raising of the temperature to a certain degree (which may be varied according to circumstances) is required to cause the alarm. The instrument is merely a scientific application of the fact that the heat causes expansion. As soon as the metal in the little apparatus becomes affected by the rise in temperature, which must inevitably take place immediately a fire breaks out, it expands, completes an electric circuit, and the bell, which may be placed anywhere—at the fire station, if desired—rings. An ingenious arrangement regulates the degree of heat at which the instrument shall give warning. In a room, where, by reason of the work carried on, the temperature is ordinarily high, the point at which the warning shall be given must obviously be proportionately higher. A turn of a little clock hand is all that is required to effect it. It is claimed that the instrument may be so sensitive that merely breathing upon it will cause the alarm to be given.”