The base of this light bulb is large and bulky, has a copper screw shell with two or three threads (which serve as one contact terminal) over a wooden insulator and a separate cone-shaped copper ring (being the second contact terminal) also over the same wooden insulator and separated from and above the threads.  The base also has a wide wooden ring or collar for holding and twisting bulb into its socket.  The base is cemented to the neck of the bulb by a thick ring of plaster of paris between the bulb and base.

“This bulb may come with a wooden screw socket with female threads inside and a thumbscrew on the side of the socket for tightening the base in the socket. [See A115]  This is the first threaded base used for light bulbs and was developed in late 1880.  It is recorded that Thomas Edison, while discussing with his team the need of a better way of attaching the light bulb to the electrical circuit, conceived the idea of a threaded base and socket while noticing an oil can resting on a nearby shelf.  Edison removed the oil can from the shelf and unscrewed the cap off.  After carefully examining the cap for a moment, Edison then exclaimed to the others, “This certainly would make up a bang-up socket for the lamp!"



 
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