Electric filament lamps made by Swan (left) and Edison (right), 1878-1879.
© Science Museum / Science & Society Picture Library
The lamp on the left is an early carbon and rod filament incandescent electric lamp made by the English chemist, Joseph Swan (1827-1914) in 1878-1879. The lamp on the right, made by the American physicist, Thomas Alva Edison (1847-1931), has a single loop of carbon which glowed when a current flowed through it. The glas bulb (made by the glas blower, Boehm) was evacuated so that there was so little oxygen in the bulb that the filament could get white hot without burning. Edison's lamp was made in 1879, one year after Joseph Swan's pioneering electric light bulb, but both were obsolete by the time Swan and Edison joined forces in Britain in 1883 to form the Edison and Swan United Electric Light Company.