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 of the safety lamp. The miner was expected to return to the shaft to perform relighting, a round trip of up to a few miles. For men on piece work, this meant a loss of income (perhaps 10% of their day's pay) and so was unpopular. From the mid-century onwards, and particularly after the 1872 act, lamps had to have a lock mechanism which prevented the miner opening the lamp. Two schemes existed; either a special tool was required which kept at the pit head or else opening the lamp extinguished the flame. The latter mechanism can be seen in