1894

In the mid 1890s, wider filaments that took up more bulb space and also had higher wattages which generated more heat were being developed.  Hence in 1894, in order to accommodate these larger filaments and dissipate the excess heat so that the base would not melt, bases with wide skirts were introduced.  The base of this bulb has a copper screw shell with a wide skirt above its 4 to 6 threads (which serve as one contact terminal) and one straight-sided or tapered copper contact (which serves as the second terminal) at the bottom of the base, all over a plaster of paris insulator. See examples of filament configurations: [see A116] (filament with anchored loop), [see A117] (two filaments connected in series), and [see A119] (squirrel cage filament configuration).

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