1879 to 1880

This is the next filament conceived by Thomas Edison.  It is vertically flat and shaped like a small horseshoe with rectangular ends that connect to inner leads.  This filament was made of carbonized Bristol cardboard.  It was used in Edison’s first commercial lamps that he sold in 1879 and 1880.  It could burn for some 600 hours.

NEXT PAGE in the Evolution of Filaments

close window