In 1878 he formed the Edison Electric Light company, with the goal to generate electric power that would be cheaper to produce and provide a source for illumination.
From the period of 1878 to 1880 Edison and his associates worked on at least three thousand different theories while developing the incandescent lamp. Edison's crew experimented on six thousand different types of materials for the filament of his electric lamp. Eventually they narrowed the choices down to two:
The platinum wire proved unsuccessful, for it could not handle the electric current without melting.
The final filament chosen was a carbonized cotton thread. The theory was that a current flowing through the thread would cause it to radiate a steady glow. The vacuum was needed to keep the filament from burning up.
On October 21, 1879, Edison and his associates were ready to test there carbon filament light bulb. For thirteen hours the bulb glowed soft orange, and then burnt out. Patent number 223898 was granted to Edison's electric lamp.