bild

Edison's light bulb patent, 1880. Printed patent drawings of the electric lamp design by US inventor Thomas Alva 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 is patent number 223,898 from the US Patent Office, dated 27 January 1880. (KEYSTONE/SCIENCE PHOTO LIBRARY/US NATIONAL ARCHIVES AND RECORDS ADMINISTRATION/SCIENCE PHOTO LIBRARY)