Page:Popular Science Monthly Volume 90.djvu/857

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��The new Sperry searchlight lamp and its predecessors. The trend in lamp design has been to provide a more intensely luminous source than that of pure carbon. Until recently this was thought impossible, because carbon possesses the highest melting point of any known element. But the newer lights, such as the Beck lamp shown above, and the Sperry lamp, have kept their carbons and metal parts from melting by ingenious means. In the Beck lamp an alcohol spray is used; in the Sperry lamp constant cnarrents of cool air are forced through the carbon supports

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