An Improved Portable Electric Resistance for use with Surgical or Medical Lamps

5374. Davidson, F. N. March 10. Begulating; switches.-To enable a low-voltage surgical or medical lamp to be used with the lighting-mains, there is inserted in series with it a resistance consisting of two lamps E, E , Fig. 1, of different candle-powers, in combination with a knife plug switch consisting of a wooden handle F carrying three blades G, G , G Fig. 2, which may be placed in any one of four rows of contacts on a vulcanite base beneath slots in a front board D, thereby placing either lamp E, E' in circuit or both lamps in series or in parallel.. The lamps E, E are arranged in tin-lined boxes on either side of the switch contacts, .the whole apparatus being portable. Fig. 4 is a rear view of the contact board, the circles representing the backs of the terminals in which the knife plug is inserted. The pairs of leads N', N. are connected to the resistance lamps E, E , the pairs of leads K, L are connected to the mains and to the low-voltage lamp respectively, and the contacts are connected as shown, the top pair J serving to hold the knife plug when the circuit is to be broken.