1. A METHOD OF MAKING A SEALED SWITCH FROM A GLASS TUBE AND A PAIR OF SWITCH ELEMENTS IN WHICH THE ELEMENTS ARE PARTIALLY INSERTED INTO OPPOSITE ENDS OF A GLASS TUBE AND SEQUENTIALLY SEALED THEREIN BY HEAT THE OPPOSITE ENDS OF THE TUBE UNTIL A SEAL IS FORMED BETWEEN THE GLASS AND THE ELEMENTS, THE METHOD ALSO INCLUDING THE STEP OF DISPLACING A GIVEN ONE OF THE ELEMENTS AFTER THE OTHER ELEMENT HAS BEEN SEALED IN THE TUBE, THE IMPROVEMENT WHICH COMPRISES THE STEPS OF HEATING ONE END OF THE GLASS TUBE TO START THE SOFTENING OF THE GLASS BEFORE THE SAID OTHER SWITCH ELEMENT IS INSERTED SO THAT THE HEAT LOSS OCCASIONED BY CONDUCTION THROUGH THE SAID OTHER ELEMENT IS REDUCED; STARTING THE HEATING OF THE OTHER END OF THE GLASS TUBE, IN WHICH END THE SAID GIVEN ONE OF THE ELEMENTS HAS BEEN INSERTED, PRIOR TO THE TERMINATION OF THE HEATING OF THE ONE END; AND TERMINATING THE HEATING OF THE ONE END OF THE TUBE DURING THE HEATING OF THE OTHER END OF THE TUBE TO START THE COOLING OF THE SEAL AT THE SAID ONE END OF THE TUBE PRIOR TO THE DISPLACEMENT OF SAID GIVEN ONE OF THE ELEMENTS.

4. IN A MACHINE FOR MAKING SEALED SWITCHES FROM A DIELECTRIC TUBE AND A PAIR OF MAGNETIC ELEMENTS, WHICH MACHINE IS OF THE TYPE HAVINGG A SUPPORT MOVABLE OVER A FIXED PATH, A TUBE CHUCK CARRIED ON THE SUPPORT, A PAIR OF MAGNETIC ELEMENT CHCUKS CARRIED ON THE SUPPORT AND DISPOSED ON OPPOSITE SIDES OF THE TUVE CHUCK, FIRST AND SECOND HEATING MEANS CARRIED ON THE TUBE CHUCK AND DISPOSED ON OPPOSITE SIDES OF THE TUBE CHECK TO HEAT OPPOSITE ENDS OF A TUBE CARRIED IN THE TUBE CHUCK, THE FIRST AND SECOND HEATING MEANS BEING MOVABLE TOWARD AND