Blast furnace stock level control comprising radioactive source and detector

Claim 1

IN A SYSTEM FOR DETECTING THE LEVEL OF STOCK IN A BLAST FURNACE, A FURNACE STRUCTURE INCLUDING OUTER WALLS THEREOF, AXIALLY ALIGNED RAY PORT ELEMENTS EXTENDING THROUGH OPPOSITE WALLS OF SAID FURNACE ON A SELECTED DIAMETER THEREOF, A SOURCE OF RADIANT ENERGY INCLUDING A SHIELDED HOLDER FOR RADIOACTIVE MATERIAL LOCATED AT THE OUTER END OF ONE OF SAID RAY PORT ELEMENTS AND A GEIGER TUBE CIRCUIT AT THE OUTER END OF THE OTHER OF SAID RAY PORT ELEMENTS FOR DETECTING THE PASSAGE OF RADIANT ENERGY THERETHROUTH, AN AMPLIFIER LOCATED REMOTELY FROM SAID FURNACE, A TRANSMISSION LINE CONNECTING SAID GEIGER TUBE CIRCUIT AND SAID AMPLIFIRE, A CONTROL CIRCUIT CONNECTED TO A POWER SOURCE, A CIRCUIT BREAKER IN SAID CONTROL CIRCUIT, AND A CONNECTION BETWEEN THE OUTLET OF SAID AMPLIFIRE AND SAID CIRCUIT BREAKER FOR OPERATING THE LATTER UPON THE PASSAGE OF RADIANT ENERGY FROM SAID RADIANT ENERGY SOURCE TO SAID GEIGER TUBE CIRCUIT.