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 the lower brass ring supporting the glass. The lamp is in part a development of the Geordie. Air enters into a ring near the base which is protected by gauze or perforated plate. The air passes down the side of the lamp passing through a series of gauze covered holes and enters the base through another yet another series of gauze covered holes. Any attempt to unscrew the base causes the lever (shown at "f" in the illustration) to extinguish the flame. The gauze covered holes and passageways restrict the flow to that required for combustion, so if any part