A carbon filament lamp is an early form of incandescent electric light bulb in which a thin filament of carbon, sealed inside an evacuated glass bulb, glows when an electric current passes through it. Its light is soft and warm, with a distinctly amber tone, and the looped or zigzag filament is clearly visible through the clear glass.
Practical carbon filament lamps were developed independently around 1879 and 1880 by Joseph Swan in England and Thomas Edison in America, whose interests in Britain were later combined in the Ediswan company. They made electric lighting possible in homes, theatres and public buildings, and early installations in country houses were often powered by private generating plants. Carbon lamps were inefficient and blackened with age, and they were gradually displaced in the early twentieth century by lamps with metal filaments, especially tungsten. Genuine early bulbs, often with a pointed tip where the glass was sealed, are now collected as items of technological history. Reproduction filament-style bulbs are widely used today with antique and industrial fittings, as their warm glow suits period lighting far better than harsh modern light.
