The "Grain of Wheat" Lamp

A sample of perhaps the smallest incandescent lamp ever manufactured by the General Electric Company is pictured above; it was referred to as the "grain of wheat" lamp. It was designed to be used in children's surgical instruments. It operates from one dry cell. The lamp consumes 0.17 watt and produces 0.35 lumen. The envelope diameter is 0.058-inch and the tube length, 0.33-inch. It is used with a cylindrical metal lamp holder. The tungsten filament is singly coiled and the lamp interior is evacuated.

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