Thomas Edison was a prolific American inventor who held more than 1,000 patents on his inventions, including important innovations such as the incandescent electric lamp (1879) and the phonograph (1877). Contrary to popular belief, he didn't "invent" the light bulb, but rather he improved upon a 50-year-old idea. Edison’s light bulb (1879) used a small, carbonized filament that lasted 40 hours because Edison was able to maintain a good vacuum. On September 4, 1882, Edison opened the first commercial power station, located on Pearl Street in lower Manhattan that provided light and electricity power to customers in a one square mile area. This signaled the beginning of the electric era. Edison invested in DC power transmission and fought bitterly against Tesla and Westinghouse's AC transmission. Edison would be proven wrong on this front, as AC was much more convenient to transmit since it can be produced at high enough voltages to be transmitted over large distances, where as DC cannot. His notable scientific discovery was the Edison effect, the emission of electrons from a heated cathode. Edison did not recognize the importance of this discovery, though subsequent scientists used the effect as the basis for the electron tube. Edison is famous for his slogan "genius is 1% inspiration and 99% perspiration."