Abstract
A DEVICE, invented in France, which can be used either as a fire alarm which will give automatically a telephone message to the fire brigade, or as a burglar alarm which will summon the police, is described in The Times of December 7. The apparatus is called a ‘signaphone’, and is already installed in about forty buildings in Paris. When used as a fire alarm, the device is operated either by thermostats fixed near the ceiling, or by push buttons so that a watchman has only to press the nearest button. The thermostats are operated by hot air rising to the ceiling when fire breaks out. This breaks a closed electric circuit, and an electrical relay at once starts a clockwork motor. The motor drives a small dialling drum, the small metal discs on which correspond to the letters and figures of the telephone number of the nearest fire station. The station is thus called up and a gramophone record then comes into action giving, in a verbal message, the location of the fire and all essential details. This message is repeated continuously for 31 minutes. If necessary, also, it can be made to ring up a second number for example, that of the owner of the building and repeat its message. When used as a burglar alarm, the signaphone is connected with an electric circuit in the building. In this case, a burglar who opens a door or window, takes down a picture or tries to open a safe or desk, without knowing it thereby summons the police, who learn from the the gramophone message what is happening. Anyone who desires to have both a fire and burglar alarm must have two signaphones installed. The Post Office has given permission for these devices to be attached to telephones on automatic exchanges. It has also met with the approval of the Metropolitan Police, to whom it has been demonstrated.
Article PDF
Rights and permissions
About this article
Cite this article
Automatic Fire and Burglar Alarms. Nature 136, 946–947 (1935). https://doi.org/10.1038/136946d0
Issue Date:
DOI: https://doi.org/10.1038/136946d0