Fire detecting device

Claim 1

IN A FIRE DETECTING DEVICE, THE COMBINATION OF: (A) A FIRST LIGHT SENSITIVE RESISTOR CONNECTED TO FORM ONE ARM OF A WHEATSTONE BRIDGE; (B) A SECOND LIGHT SENSITIVE RESISTOR CONNECTED TO FORM A SECOND ARM OF SAID BRIDGE AND PROVIDE A NULL POINT BETWEEN SAID FIRST AND SECOND ARMS; (C) A POTENTIOMETER HAVING FIRST AND SECOND SEGMENTED PORTIONS OF ITS RESISTANCE WINDING CONNECTED TO FORM RESPECTIVELY THIRD AND FURTH ARMS OF SAID BRIDGE AND A MOVABLE CONTACT TO ADJUST SAID POTENTIOMETER TO EFFECT A BALANCE OF SAID BRIDGE AND WITH SAID RESISTANCE WINDING FORM A SECOND NULL POINT ON SAID BRIDGE; (DX) AN ELECTRICALLY ENERGIZED LIGHT SOURCE SO ARRANGED THAT THE RAYS THEREOF IMPINGE CONTINUOUSLY UPON SAID FIRST LIGHT SENSITIVE RESISTOR; (E) A CHASSIS ON WHICH FIRST AND SECOND LIGHT SENSITIVE RESISTORS AND SAID LIGHT SOURCE ARE MOUNTED, WHICH CHASSIS HAS A FIRST SMOKE CHAMBER THEREIN OPEN TO THE LIGHT FROM SAID SOURCE AND SO ARRANGED AS TO TRANSMIT LIGHT TO SAID FIRST LIGHT SENSITIVE RESISTOR, WITH SAID CHASSIS HAVING A SECOND SMOKE CHAMBER COMMUNICATING WITH SAID FIRST SMOKE CHAMBER THAT IS SO ARRANGED AS TO RECEIVE AND TRANSMIT LIGHT REFLECTED FROM INDIVIDUAL SMOKE PARTICLES TO SAID SECOND LIGHT SENSITIVE MEANS, AND SMOKE FROM SAID FIRE CONDUCTIVE INTO SAID SMOKE CHAMBER DECREASING THE INTENSITY OF LIGHT TRANSMITTED TO SAID FIRST LIGHT SENSITIVE MEANS AND INCREASING THE INTENSITY OF LIGHT TRANSMITTED TO SAID SECOND LIGHT SENSITIVE MEANS; (F) AN ELECTRIC CIRCUIT FOR SUPPLYING ELECTRIC ENERGY TO SAID FIRST AND SECOND RESISTORS AND SAID LIGHT SOURCE; (G) A MOUNTING PLATE FOR SUPPORTING SAID CHASSIS; (H) A HOUSING ENCLOSING SAID CHASSIS ATTACHED AT ONE END TO SAID MOUNTING PLATE TO FORM VENT OPENINGS IN SAID HOUSING AND OPEN AT ITS OTHER END; (I) A COVER FOR CLOSING THE OPEN END OF SAID HOUSING; (J) A LIGHT SHIELD ATTACHED TO SAID COVER, SAID LIGHT SHIELD HAVING A SURFACE THEREOF ARRANGED TO ENGAGE A GROOVE IN SAID HOUSING IN SNAP-ON FASHION, WHICH COVER AND LIGHT SHIELD ARE CONNECTED TO FORM A PORT, WITH SAID SOURCE OF LIGHT HEATING THE INTERIOR OF SAID HOUSING TO THE EXTENT THAT COOL AIR FROM THE AMBIENT ATMOSPHERE IS CONTINUOUSLY DRAWN INTO THE INTERIOR OF SAID HOUSING TO REPLACE HEATED AIR IN SAID HOUSING THAT ESCAPES UPWARDLY THROUGH SAID VENT; (K) AN ELECTRICALLY OPERATED ALARM THAT FORMS A PART OF SAID CIRCUIT AND IS ENERGIZED BY THE UNBALANCE OF SAID BRIDGE, WITH SAID UNBALANCE OCCURING WHEN WHITE SMOKE IS DRAWN INTO SAID HOUSING DUE TO THE ESCAPE OF HEATED AIR THEREFROM IN A SUFFICIENT QUANTITY THAT THE INTENSITY OF THE BEAM OF LIGHT REFLECTED TO SAID FIRST RESISTOR IS DECREASED TO INCREASE THE RESISTANCE OF SAID FIRST RESISTOR AND THE INDIVIDUAL PARTICLES OF SAID WHITE SMOKE IN SAID HOUSING SERVE AS A REFLECTORY MEDIUM TO REFLECT A PORTION OF SAID BEAM OF LIGHT TO SAID SECOND RESISTOR TO DECREASE THE RESISTANCE THEREOF, AND SAID UNBALANCE OCCURING WHEN BLACK SMOKE IS DRAWN INTO SAID HOUSING IN SUCH QUANTITY AS TO SUBSTANTIALLY OBSTRUCT THE PASSAGE OF THE REFLECTED BEAM OF LIGHT FROM SAID MIRROR TO SAID FIRST RESISTOR, AS WELL AS THE REFLECTION OF A PORTION OF SAID BEAM OF LIGHT BY THE PARTICLES IN SAID BLACK SMOKE TO SAID SECOND RESISTOR.