Nuts and Volts - March 2018

140 Years of Incandescent Light

If you ask the average person, “Who invented the light bulb,” the answer will likely be “Thomas Edison.” However, it’s not quite that simple. The earliest patent was granted 140 years ago to English chemist, Joseph Swan, and even his invention was built upon earlier achievements by Alessandro Volta and Humphry Davy. An early light bulb designed by Warren de la Rue worked reasonably well but used a coiled platinum filament, which was too expensive to allow commercial success. It also had high conductance, which limited its working life.

In 1860, Swan partially solved the cost problem by replacing the platinum with a carbonized paper filament, and he received a patent in the UK in 1878. This version, however, proved impractical because vacuum pumps in that era were not efficient enough to create a strong vacuum. A year later, Edison demonstrated his bulb, which featured a better vacuum and incorporated a thin filament with high electrical resistance, thus requiring only a small current to make it glow.

Swan adopted Edison’s improvements and started his own electrical lighting company in England. After losing a patent infringement suit against Swan, the two joined forces and created Edison & Swan Electric Light Co. Ltd., which became one of the world’s largest light bulb manufacturers. The rest, as they say, is history. ;