Thomas Edison and the Canadian connection of the Electric Incandescent Light Bulb

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• published: 02 Apr 2015
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Thomas Edison is usually credited with the invention of the light bulb, but the famous American inventor wasn't the only one who contributed to the development of this revolutionary technology. The story of the light bulb begins long before Edison patented the first commercially successful bulb in 1879. In 1800, Italian inventor Alessandro Volta developed the first practical method of generating electricity, the voltaic pile. Made of alternating discs of zinc and copper — interspersed with layers of cardboards soaked in salt water — the pile conducted electricity when a copper wire was connected at either end. While actually a predecessor of the modern battery, Volta's glowing copper wire is also considered to be one of the earliest manifestations of incandescent lighting. Not long after Volta presented his discovery of a continuous source of electricity to the Royal Society in London, an English inventor named Humphrey Davy produced the world's first electric lamp by connecting voltaic piles to charcoal electrodes. Davy's 1802 invention was known as an electric arc lamp, named for the bright arc of light emitted between its two carbon rods. While Davy's arc lamp was certainly an improvement on Volta's stand-alone piles, it still wasn't a very practical source of lighting. This rudimentary lamp burned out quickly and was much too bright for use in a home or workspace. But the principles behind Davy's arc light were used throughout the 1800s in the development of many other electric lamps and bulbs. In 1840, British scientist Warren de la Rue developed an efficiently designed light bulb using a coiled platinum filament in place of copper, but the high cost of platinum kept the bulb from becoming a commercial success. And in 1848, Englishman William Staite improved the longevity of conventional arc lamps by developing a clockwork mechanism that regulated the movement of the lamps' quick-to-erode carbon rods. But the cost of the batteries used to power Staite's lamps put a damper on the inventor's commercial ventures. In 1850, English chemist Joseph Swan solved the cost-effectiveness problem of previous inventors by developing a light bulb that used carbonized paper filaments in place of ones made of platinum. Like earlier renditions of the light bulb, Swan's filaments were placed in a vacuum tube to minimize their exposure to oxygen, extending their lifespan. Unfortunately for Swan, the vacuum pumps of his day were not efficient as they are now, and his first prototype for a cost-effective bulb never went to market. While Swan waited for the development of quality vacuum pumps, an American inventor, Charles Francis Brush, was busy developing an electric arc lighting system that would eventually be adopted throughout the United States and Europe during the 1880s. While not truly a light bulb, Brush's lighting systems could be used wherever bright lights were needed — such as in streetlights and inside commercial buildings. To power his systems, Brush developed dynamos — or electric generators — similar to those used that would one day be used to power Edison's electric lamps. In 1874, Canadian inventors Henry Woodward and Matthew Evans filed a patent for an electric lamp with different-sized carbon rods held between electrodes in a glass cylinder filled with nitrogen. The pair tried, unsuccessfully, to commercialize their lamps but eventually sold their patent to Edison in 1879. Edison and his team of researchers in Edison's laboratory , tested more than 3,000 designs for bulbs between 1878 and 1880. In November 1879, Edison filed a patent for an electric lamp with a carbon filament. The patent listed several materials that might be used for the filament, including cotton, linen and wood. Edison spent the next year finding the perfect filament for his new bulb, testing more than 6,000 plants to determine which material would burn the longest. Several months after the 1879 patent was granted, Edison and his team discovered that a carbonized bamboo filament could burn for more than 1,200 hours. Bamboo was used for the filaments in Edison's bulbs until it began to be replaced by longer-lasting materials in the 1880s and early 1900s. In 1882, Lewis Howard Latimer, one of Edison's researchers, patented a more efficient way of manufacturing carbon filaments. And in 1903, Willis R. Whitney invented a treatment for these filaments that allowed them to burn bright without darkening the insides of their glass bulbs. William David Coolidge, an American physicist with General Electric, improved the company's method of manufacturing tungsten filaments in 1910. Tungsten, which has the highest melting point of any chemical element, was known by Edison to be an excellent material for light bulb filaments, but the machinery needed to produce super-fine tungsten wire was not available in the late nineteenth century. Tungsten is still the primary material used in incandescent bulb filaments today.