Safety lamp it. Air is drawn in and descends just inside the glass, passing up through the flame in the centre of the lamp. The outer casings of lamps have been made of brass or tinned steel. If a lamp bangs against a hard piece of rock a spark could be generated if iron or untinned steel were employed. Within months of Clanny's demonstration of his first lamp, two improved designs had been announced: one by George Stephenson, which later became the Geordie lamp, and the Davy lamp, invented by Sir Humphry Davy. Subsequently, Clanny incorporated aspects of both lamps and produced
Safety lamp a scientific instrument for detecting the presence of firedamp". Some pits continued to use candles for illumination, relying on the Davy to warn men when to extinguish them. In the earlier Geordie lamps an oil lamp is surrounded by glass. The top of the glass has a perforated copper cap with a gauze screen above that. The glass is surrounded by a perforated metal tube to protect it. Later versions had an annular chamber around the base of the lamp into which air entered through small (") holes and from which air passed through gauze into the lamp. The glass