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A device for securing the safety of timbermen and other workmen employed underground in mines
A device for securing the safety of timbermen and other workmen employed underground in mines
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机译:一种用于确保矿山地下工人和其他工人安全的装置
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摘要
191,933. Douglas, D. Dec. 16, 1921. Shields for miners.-In a shield for miners' use comprising a curved plate supported on telescopic legs, slidable plates are provided beneath the curved plate to extend the protective surface.
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