Geordie lamp the base so that it gave more light and tried new versions on 4 and 30 November. This was presented to the Literary and Philosophical Society (Lit & Phil) of Newcastle upon Tyne on 5 December 1815. Although controversy arose between Stephenson's design and the Davy lamp (invented by Humphry Davy in the same year), Stephenson's original design worked on significantly different principles from Davy's final design. If the lamp were sealed except for a restricted air ingress (and a suitably sized chimney) then the presence of dangerous amounts of firedamp in the incoming air would (by its combustion) reduce
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