Electric alarm system, preferably for fire alarms

Claim 1

AN AREA MONITORING ELECTRIC ALARM SYSTEM PREFERABLY FOR FIRE ALARMS COMPRISING, TWO METALLIC IONIZING CHAMBERS CONNECTED TOGETHER AT A COMMON WALL, THE CHAMBERS HAVING REGISTERED APERTURES IN THE COMMON WALL FOR INTERCOMMUNICATION BETWEEN THE INTERIORS OF THE CHAMBERS, ONE OF THE CHAMBERS HAVING CLOSED WALLS TO THE AREA TO BE MONITORED, THE OTHER CHAMBER HAVING WALLS OPEN TO THE AREA TO BE MONITORED, THE CHAMBERS BEING CONNECTED ACROSS TERMINALS OF A VOLTAGVE SOURCE, AN ELONGATED RADIOACTIVE RADIATING MEMBER DISPOSED WITHIN BOTH CHAMBERS THROUGH THE REGISTERED APERTURES THE RADIATING MEMBER BEING DISPLACEABLE IN ITS LONGITUDINAL DIRECTION RELATIVE TO THE CHAMBERS, A PLURALITY OF INTERCONNECTING ELECTRODES IN BOTH OF THE CHAMBERS, A VOLTAGE SENSITIVE INDICATING MEMBER ELECTRICALLY CONNECTED TO THE ELECTRODES, THE ELECTRODES BEING IN THE FORM OF A METAL GRID SURROUNDING THE RADIATING MEMBER ALONG AT LEAST A PART OF THE LENGTH OF THE RADIATING MEMBER, AND SAID COMMON WALL MUTUALLY SEPARATING AND ELECTRICALLY INSULATNG THE IONIZING CHAMBERS AND THE RADIATING MEMBER.