This is a un-tipped, drawn tungsten lamp, whose filament has a very low electrical resistance so that it is longer (approximately two feet in total length) and thinner than a carbon filament. Drawn tungsten filaments were beginning to be replaced by the shorter coiled tungsten filaments about the same year that the tip-less bulbs came out in 1919. So this bulb dates from 1919 afterwards. It is not known in what year the un-tipped, drawn tungsten lamps were fully discontinued. For further dating, if the top of the bowl of the bulb has the MAZDA trademark and the
GE monogram on a label or sticker [see A44a?]
affixed to the outside surface of bulb or to the stem tube inside bulb, the bulb should date from 1919 until 1926, when etched trademarks first appeared. If the bulb should have the MAZDA name, GE monogram, wattage, and voltage etched on the top of bulb [see A44]
, bulb was manufactured after 1926.
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