The basic idea of using electricity to create light was first investigated over 200 years ago by the English chemist Humphrey Davy. He showed that when electric current flowed through wires, their resistance caused them to heat up to the point where they gave out light. But he also identified the key problem to creating the first practical ‘incandescent light’: finding a cheap material that both burned brightly, and lasted for many hours. US inventor Thomas Edison is often credited with creating the solution in 1879: the carbon filament light bulb. Yet the British chemist Warren de La Rue had solved the scientific challenges nearly 40 years earlier.
He used thin – and thus high-resistance – filaments to achieve the brightness, and delayed burnout by making them from high-melting-point metal sealed in a vacuum. His choice of pricey platinum for the filament and the difficulties of achieving a good vacuum made the result uneconomic, however. In 1878, another British chemist, Joseph Swan, publicly demonstrated the first light based on commercially-viable carbon, but his use of relatively thick filaments still led to rapid burnout. Edison’s combination of thin carbon filament design with better vacuums made him the first to solve both the scientific and commercial challenges of light bulb design.