Canadian Inventions – The Light Bulb

Thomas Edison, an American, is almost unanimously credited with inventing the incandescent light bulb. However, two Canadians, Henry Woodward and Matthew Evans, successfully produced and patented an electric filament lamp before Edison had seriously turned his mind to electric lighting. Although the young Toronto inventors successfully manufactured their incandescent lamp years before Edison produced his first prototype, they were not nearly as successful promoting the new technology. After repeated unsuccessful attempts to find financial backers, the pair sold their patents to Edison who was eventually able to commercialize the light bulb and the electrical distribution networks necessary to power it. Woodward and Evans began experimenting with electrical lighting in 1873. One night the two were testing an induction coil Woodward had made when they realized the spark being created by the coil was illuminating their small workbench they were using. They soon devised a way to produce a sustained electrical light. Woodward and Evans reasoned that passing current through a high resistance filament would increase the temperature of the filament material and cause it to glow, emitting light to the surroundings. The pair experimented with various possible filaments before developing a carbon rod for their prototype. They housed the carbon rod filament within a glass tube taken from a boiler level indicator and connected electrodes to either end. Finally, before testing their crude light tube, Woodward and Evans replaced the air within the tube with nitrogen to prevent the carbon rod from catching fire. Woodward and Evans tested the light tube at a Toronto foundry in 1874, coupling the electrodes to the terminals of an industrial battery. The carbon rod filament took some time to heat up, but eventually emitted enough light to illuminate the immediate surroundings. Evans later recounted the experiment:

"There were four or five of us sitting around a large table. Woodward closed the switch and gradually we saw the carbon become first red and gradually lighter and lighter in colour until it beamed forth in beautiful light.”

Woodward was encouraged by the experimental results and soon invested in an advanced dynamo to power the lights. He and Evans also applied for, and were granted, patents in Canada and the US for their incandescent light tube. The pair then set about finding funding that would enable them to refine the light tube for production. However, they soon realised that the people they approached did not share their enthusiasm for the electric light. Potential investors often dismissed them with little consideration and they were ridiculed for promoting such a ‘useless’ invention. Woodward and Evans endeavoured to refine and commercialize their light bulb with little success, eventually succumbing to a lack of funding and selling their patent rights to Edison in 1879 for US$5,000 (or about $100,000 in today’s dollars). With access to the necessary funding, Edison was able to develop an improved product and promote it. Demand for electric lighting grew rapidly. In 1885 an estimated 300,000 electric lamps were sold in the United States, all with carbon filaments. In Canada, by 1900 electric lights were slowly making their way into Toronto households. Summary by: Richard Murphy