Yablochkov candle

The Yablochkov candle is another type of electric carbon arc lamp. The candle consists of two carbon blocks separated by a block of plaster and burns with an even glow when supplied with alternating current. The burn time of the ‘candle’ is about two hours.
Gramme developed a special alternator with a commutator. This allowed the next candle in a series to be lit when the preceding candle burned out. Unlike the original arc lamp, no special mechanism was required for proper operation. The candle works in the ordinary atmosphere.