"S" type "Thor" miners electric safety lamp

"S" type "Thor" miners electric safety lamp no.S.8498 with dioptric glass and cell case and magnetic lock.

This is a pillar type of electric lamp made from pressed steel, in two portions, fitting together by a bayonet joint which may be locked either by a lead plug, as in the example, or by a magnetic bolt. The lower portion, of cylindrical construction, carries the accumulator, which is encased in a vulcanite container in place of the more usual celluloid. Spring terminals are provided on the accumulator to maintain close contact with the light bulb. A specially shaped glass (the central portion of which is shaped as a dioptric lens) is fitted over the bulb as a protection against injury. The cover glass is frosted, to diffuse the light and reduce the liability of the miner to nystagmus. The lamp is switched on or off by rotating the lower portion relative to the upper.