1880

During the last few months of this year, Thomas Edison developed the first threaded base for the light bulb.  This base was large and bulky, had a copper screw shell with two or three threads (which served as one contact terminal) molded over a wooden insulator and a separate cone-shaped copper ring (being the second contact terminal) that was also molded over the same wooden insulator but kept separated from and above the threads.  This base also had a wide wooden ring or collar for holding and twisting the bulb into its socket.  The base was cemented to the neck of the bulb by a thick ring of plaster of paris between the bulb and base.

This bulb was meant to be mounted into a wooden screw socket with female threads inside and a thumbscrew on the side of the socket for tightening the base into the socket. [see A115] This is the first threaded base used for light bulbs.  It is recorded that Thomas Edison, while discussing with his team the need of a better way of attaching a 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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