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These are GEM (General Electric Metallized) filament lamps.  The GEM filament was invented by Dr. Willis Rodney Whitney [see A48] of the General Electric Company in Schenectady and manufactured from 1905 to 1918.  The GEM lamps pictured above have a single filament (left), two hair-pin filaments (center), and a single oval anchored filament (right).  Although GEM light bulbs were successfully marketed to the public, the lamps faced competition from the newer and more popular tungsten lamps [see A27].  Manufacturing of all GEM lamps ceased in 1918 during the First World War when the United States Fuel Administration asked that all incandescent lamp manufacturers abandon the production of many carbon lamps, including the GEM lamps.  This was an unprecedented energy conservation movement that probably saved one million tons of coal every year.  GEM lamps were subsequently replaced by tungsten lamps.

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