October 22nd, 1879: Thomas Edison successfully tested an electric incandescent lamp with a carbonized filament at his laboratory in Menlo Park, New Jersey, keeping it lit for over 13 hours. Edison continued to improve this design and by November 4, 1879, filed for U.S. patent 223,898 (granted on January 27, 1880) for an electric lamp using “a carbon filament or strip coiled and connected to platina contact wires”. This was the first commercially practical incandescent light.
