A "'methanometer "'is an instrument used to measure methane gas in the air of a mine.
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The Methanometer could be powered by an Edison battery cap lamp and it could be carried on a miner's belt with other tools.
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The Mine Safety Appliances Company Ltd . manufactured the first type-W8 Methanometer around 1950 and it was approved for use by the Ventilation Regulations of 1947.