In this lamp the graphite rods operated in a vacuum.
Kosloff, another Russian, in 1875 patented a graphite in nitrogen incandescent lamp, which had several graphite rods for burners, so arranged that when one failed another was automatically connected. Konn, also a Russian, made a lamp similar to Kosloff’s except that the graphite rods operated in a vacuum. Bouliguine, another Russian, in 1876 made an incandescent lamp having a long graphite rod, only the upper part of which was in circuit. As this part burned out, the rod was automatically pushed up so that a fresh portion then was in circuit. It operated in a vacuum. None of these lamps was commercial as they blackened rapidly and were too expensive to maintain.
Bouliguine’s Incandescent Lamp, 1876.
A long graphite rod, the upper part of which only was in circuit, operated in vacuum. As this part burned out, the rod was automatically shoved up, a fresh portion then being in the circuit.
THE JABLOCHKOFF “CANDLE”
Paul Jablochkoff was a Russian army officer and an engineer. In the early seventies he came to Paris and developed a novel arc light. This consisted of a pair of carbons held together side by side and insulated from each other by a mineral known as kaolin which vaporized as the carbons were consumed. There was no mechanism, the arc being started by a thin piece of carbon across the tips of the carbons. Current burned this bridge, starting the arc. The early carbons were about five inches long, and the positive carbon was twice as thick as the negative to compensate for the unequal consumption on direct current. This, however, did not work satisfactorily. Later the length of the carbons was increased, the carbon made of equal thickness and burned on alternating current of about eight or nine amperes at about 45 volts. He made an alternating current generator which had a stationary exterior armature with interior revolving field poles. Several “candles,” as they were called, were put in one fixture to permit all night service and an automatic device was developed, located in each fixture, so that should one “candle” go out for any reason, another was switched into service.
Jablochkoff “Candle,” 1876.
This simple arc consisted of a pair of carbons held together side by side and insulated from each other by kaolin. Several boulevards in Paris were lighted with these arc lights. This arc lamp is in the collection of the Smithsonian Institution.