Monday, 22 October 2012

On This Day: 22nd October 1878 Thomas Edison successfully tests the first ‘light bulb’

For more than three quarters of a century, scientists had been working to develop an electric light. Thomas Edison himself began developing a practical incandescent lamp in 1878 and filed his first patent application for "Improvement In Electric Lights" on 14 October 1878. During two-years of research, Edison and his colleagues worked on at least three thousand different theories to develop an efficient incandescent lamp.

The first successful test was on 22 October 1879, and lasted 13.5 hours. Later in 1878, Edison formed the Edison Electric Light Company in New York City with several financiers, including J. P. Morgan and the Vanderbilt family. Edison continued to improve this design and on 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 wire.

Although the patent described several ways of creating the carbon filament including "cotton and linen thread, wood splints, papers coiled in various ways",it was not until several months after the patent was granted that Edison and his team discovered a carbonized bamboo filament that could last over 1,200 hours.

Edison made the first public demonstration of his incandescent light bulb on December 31, 1879.

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Image courtesy of the US National Archives under The Commons Agreement on Flickr

Research courtesy of Wikipedia


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