Temperature responsive control

Claim 1

IN A CONTROL FOR A SURFACE HEATING UNIT OR THE LIKE, THE COMBINATION OF A MAIN CYCLING SWITCH COMPRISING A PAIR OF CONTACTS, TEMPERATURE RESPONSIVE MEANS OPERABLE TO MOVE ONE OF SAID CONTACTS IN OPENING DIRECTION UPON INCREASE IN TEMPERATURE AND IN CLOSING DIRECTION UPON DECREASE IN TEMPERATURE, AND MEANS FOR HEATING SAID TEMPERATURE RESPONSIVE MEANS UPON PASSAGE OF ELECTRICAL CURRENT THROUGH SAID CONTACTS, WHEREBY SAID CONTACTS ARE CYCLICALLY OPENED AND CLOSED TO CONTROL THE PERCENTAGE OF "ON" TIME OF THE CIRCUIT CONTROLLED THEREBY, SAID MAIN CYCLING SWITCH INCLUDING TEMPERATURE RESPONSIVE MEANS FOR ADJUSTING THE SETTING THEREOF; AND A CONTROL CIRCUIT FOR SAID MAIN CYCLING SWITCH INCLUDING A HEATING ELEMENT ARRANGED TO HEAT SAID LAST-MENTIONED TEMPERATURE RESPONSIVE MEANS AND A SECOND CYCLING SWITCH CONTROLLING SAID HEATING ELEMENT, THE LATTER SWITCH COMPRISING A PAIR OF CONTACTS IN SERIES WITH SAID HEATING ELEMENT, A TEMPERATURE RESPONSIVE ELEMENT OPERABLE TO MOVE ONE OF THE CONTACTS OF SAID SECOND CYCLING SWITCH IN OPENING DIRECTION UPON INCREASE IN TEMPERATURE AND IN CLOSING DIRECTION UPON DECREASE IN TEMPERATURE, SAID TEMPERATURE RESPONSIVE ELEMENT BEING HEATED UPON PASSAGE OF CURRENT THROUGH SAID SECOND CYCLING SWITCH CONTACTS, WHEREBY SAID LATTER CONTACTS ARE CYCLICALLY OPENED AND CLOSED TO CONTROL THE AVERAGE WATTAGE DELIVERED TO SAID HEATING ELEMENT, AND A SECOND TEMPERATURE RESPONSIVE ELEMENT OPERABLE TO CONTROL THE ACTION OF SAID SECOND CYCLING SWITCH TO VARY THE PERCENTAGE OF "ON" TIME THEREOF IN RESPONSE TO VARIATION IN ITS TEMPERATURE, THE FREQUENCY OF CYCLING OF THE SECOND CYCLING SWITCH BEING SEVERAL TIMES THE FREQUENCY OF CYCLING OF THE MAIN CYCLING SWITCH.