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
Tensor lamp Tensor lamp Tensor lamp is a small high-intensity and low-voltage desk lamp invented by Jay Monroe. The lamp was mainly popular during the 1960s and 1970s. The lamp was originally used by doctors and dentists, and later became more widely used. The first Tensor lamp consisted of assembling together a 12-volt automobile parking light bulb and reflector made from an ordinary kitchen measuring cup. Monroe fixed the cup to a metal tube that was attached to a transformer, which reduced 115-volt house current to 12 volts. Because of the small bulb, the entire lamp could be made smaller with a