The base of this bulb is smaller and less bulky than the base of the previous bulb.  It has a copper screw shell with two or three threads (which serve as one contact terminal) over a wooden insulator as well as a separate cone-shaped copper ring (being the second contact terminal) also over the same wooden insulator and above the threads.   The wooden collar for holding and screwing the bulb into a socket is also smaller.  The socket itself would have female threads to place and tighten socket in.  This base is cemented to the neck of the bulb by a thick ring of plaster of paris between the bulb and base.  It was introduced in February of 1881.



 
close window