Denton, Greater Manchester and then abandoned. After hatting, the most important industry in Denton was the manufacture of lead-acid batteries by Oldham Batteries (Oldham & Son Ltd). In 1865, Joseph Oldham established a millwright general engineering shop and by 1887 this company was manufacturing machinery for the hat-making industry. Another important industry in the area was coal mining and shortly after 1887 the company began making machinery and equipment for this industry, which included miners' portable lamps. Up to this time, miners had always used the safety lamp devised in 1815 by Sir Humphry Davy (1778–1829) but this new battery-powered Davy lamp eventually
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