Electric fire-detector cable

Claim 1

A RESISTANCE-TYPE TEMPERATURE-RESPONSIVE CABLE COMPRISING A TUBULAR SHEATH OF A DUCILE NICKEL-IRON ALLOY, A COPPER-CLAD NICKEL-IRON WIRE AT THE CENTER OF SAID SHEATH LENGHTWISE THEREOF, SUBSTANTIALLY PURE ELECTRONIC SEMICONDUCTIVE OXYGEN CONTAINING COMPOUND TENDING TO RELEASE OXYGEN AND TO RECOMBINE THEREWITH WITH CHANGE IN ITS RESISTIVITY AS THE COMPOUND IS HEATED AND COOLED THROUGH A TEMPERATURE RANGE BELOW ITS MELTING POINT, SAID COMPOUND FILLING THE SPACE BETWEEN SAID SHEATH AND WIRE AND CONSTITUTING A MEANS FOR HOLDING SAID WIRE CENTERED IN RELATION TO SAID SHEATH ALONG THE LENGTH OF THE CABLE, SAID SHEATH BEING CONSTRICTED TIGHTLY ONTO SAID COMPOUND AND BEING HERMETICALLY SEALED, AND SAID SHEATH AND WIRE HAVING OXIDIZED SURFACE CONTACTING SAID COMPOUND TO CAUSING THE OXYGEN PRESSURE IN SAID SHEATH TO RETURN TO SUBSTANTIALY THE SAME VALUE AFER EACH CYCLING OF THE CABLE TO A FIRING TEMPERATURE AND COOLING THEREOF TO ROOM TEMPERATURE.