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 was surrounded by gauze so that in the event of a glass breakage the Geordie became a Davy. If the current of air forced in through the tubes (later holes and gallery) by the lamp's situation was too strong, the flame grew, and the lamp could get red-hot. The lamp becomes unsafe in a current of from 8 to 12 feet per second, about twice the limit of the Davy's safe operating conditions. However, this variation in the flame was not entirely bad. The intensity of the flame, air currents being equal, gives an indication of firedamp levels, so it