Safety lamp could create a sufficient updraft that firedamp would not penetrate down the chimney. Further observations of the speed of flame fronts in fissures and passageways led him to design a lamp with fine tubes admitting the air. Sir Humphry Davy was asked to consider the problems of a safety lamp following the Felling explosion. Previous experimenters had used coal gas (chiefly carbon monoxide) incorrectly, believing it to be the same as firedamp. Davy however performed his experiments with samples of firedamp collected from pits. As an experimental chemist, he was familiar with flames not passing through gauze; his experiments enabled
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