 The Yablochkov candle is a simple arc lamp without a regulator, but it has the drawbacks that the arc cannot be restarted (single use) and a limited lifetime of only a few hours.The concept of carbon-arc lighting was first demonstrated by Humphry Davy in the early 19th century, but sources disagree about the year he first demonstrated it; 1802, 1805, 1807 and 1809 are all mentioned.Davy used charcoal sticks and a two-thousand-cell battery to create an arc across a gap.