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Edison's light bulb patent. Printed patent drawings, dated 27th January 1880, of the electric lamp design by US inventor Thomas A. Edison (1847-1931). This incandescent light bulb design had been developed by Edison in November 1879. Light was produced by passing an electric current through a coiled carbon filament (bottom), which was placed inside a glass bulb (top). Although others had developed similar light bulbs, Edison's design was the first long-lasting filament. This was patent number 223,898 issued by the US Patent Office. Edison's signature is at lower right. (KEYSTONE/SCIENCE PHOTO LIBRARY/US NATIONAL ARCHIVES AND RECORDS ADMINISTRATION/ SCIENCE PHOTO LIBRARY)