Miners incandescent electric accumulator safety lamp

Miners incandescent electric accumulator safety lamp standard size

This lamp, details of which were patented in 1912 by F. Farber, was successful in winning the first place in a Home Office competition in that year for a miners' electric safety lamp which should best fulfil certain conditions. The lower part is of corrugated and tinned sheet steel, accommodating a secondary cell having cylindrical concentric lead electrodes within which is a tube by which the gases evolved have egress but which allows no acid to escape. The upper part supporting the glow lamp is held on by a bayonet joint and locked magnetically. The lamp bulb is mounted between helical springs to obviate breakage and is protected by a glass dome and four pillars. The light is switched on and off by turning the upper part relative to the lower. The light given is from 1 to 1.5 candlepower for 12 to 16 hours.