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
Lava lamp Lava lamp A lava lamp (or Astro lamp) is a decorative novelty item, invented in 1963 by British chemist David George Smith and British accountant Edward Craven Walker, the founder of the British lighting company Mathmos. The lamp consists of a bolus of a special coloured wax mixture inside a glass vessel, the remainder of which contains clear or translucent liquid; the vessel is then placed on a box containing an incandescent light bulb whose heat causes temporary reductions in the density and viscosity of the wax. The warmed wax rises through the surrounding liquid, cools, loses its buoyancy, and