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a. A lamp for mounting on a miner's cap and receiving electric energy through a
cord which connects the lamp with a small battery.
b. An electric lamp designed
for fixing to a miner's helmet. Its principal parts are: (1) the battery, either
lead acid or alkaline; (2) the headpiece, of plastic or aluminum alloy, with
switch; and (3) a length of twin-cord cable covered with tough rubber or with
neoprene--a fire- and acid-resisting substitute. The lead-acid lamps commonly
use either a 4-V, 1.0-A bulb with a light output of about 47.5 lumens or else a
4-V, 0.8-A bulb of 38 lumens output. The headpiece is equipped with an
auxiliary, 4 V, 0.46-A bulb. Nelson
Source:
Dictionary of Mining, Mineral, and Related Terms
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