Telephonic News: Tesla's Incandescent Lamp

Friday, July 17, 1891
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278 July 18, 1891 ELECTRICAL REVIEW Q; fifffl/;.r " ll 9 ' Pr5;fi_;,i;;f7<‘/ . l ,- ,,-}\_/-' 2 l , 2`Y"2/ in it ,.,-,_-, . _ 1'esla`s Incandescent Lamp. In the accompanying engravings are illus- trated two types of improved lamps invented by Mr. Tesla, and designed for use in his recently patented system of incandescent electric lighting by means of high frequency currents. The lamp shown in Fig. 1 is designed for direct connection withacir- cuit or source of current; that shown in Fig. 2 is designed for intiucti‘ve connection with a source of current. ' In the deviceillustrated ln Fig. I, A represents a highly vacuous glass globe, in which are sealed conductors, B, C, united with two pieces of carbon G, the joint being surrounded with bronze pnwderEto effect good connection. The cups surrounding the joint are Glled with insulating plugs F of tire-clay. The ex- haustion is carried to the highest possible point. Inasmuch as there is atendency to sparkingjvhen the current is turned on before the exhaustion has been carried very high, the ends ol the' carbon are caused to approach in order that the sparks may leap across between such currents, thus lessening the danger oi injury _to the carbons. The distance apart of the carbons in the lamp is beyond sparking distance in the vacuum. The system in which this lamp is used, de- scribed in a late issue of the Rnvrsw, consists of disruptively discharging the ac- cumulated energy of a condenser through a primary circuit to produce a current of very high frequency, and then utilizing this primary circuit to induce in a secondary a current of very much higher potential. In Fig. 2 the carbons are not connected directly to the leading-in circuit, but are in- ductively connected therewith by a con- denser-like arrangement. One form of such alamp was described in the Emscrnrcan Rsvraw. J J are plugs of tire-clay con- tained in the extensions B, B* of the lamp. gil . .,, . ' I I r , The conductors G G are supported by these plugs and connected by metallic stripsM with the condenser-coatings K KR Over the outside of the stems B B1 are tittedin- sulating caps N N‘, having metallic linings 0 O‘, with terminals adapted for connection with the circuit wires. It will thus be seen that the carbons are out of contact with the supply conductors, and can only be acted upon inductively thereby. The incandes- cence to which the carbons are raised is supposed to be due to the heat developed by the rapid charge and discharge of the con- denser.