In February of 1881, Edison further improved on the base by making it smaller and less bulky than the base of the previous bulb [see A102].  It also had a copper screw shell with two or three threads (which served as one contact terminal) molded 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 was also smaller.

NEXT PAGE in the Evolution of Lamp Bases

close window