Tag Archives: Thomas Edison

The light bulb…

Picture taken at Thomas Edison National Historic Park in West Orange, New Jersey.

**On July 24, 1874 a Canadian patent was filed by a Toronto medical electrician named Henry Woodward and a colleague Mathew Evans. They built their lamps with different sizes and shapes of carbon rods held between electrodes in glass cylinders filled with nitrogen. Woodward and Evans attempted to commercialize their lamp, but were unsuccessful. They eventually sold their patent to Edison in 1879.

In 1878, Thomas Edison began serious research into developing a practical incandescent lamp and on October 14, 1878, Edison filed his first patent application for “Improvement In Electric Lights”. However, he continued to test several types of material for metal filaments to improve upon his original design and by Nov 4, 1879, he filed another U.S. patent for an electric lamp using “a carbon filament or strip coiled and connected … to platina contact wires.”

Although the patent described several ways of creating the carbon filament including using “cotton and linen thread, wood splints, papers coiled in various ways,” it was not until several months after the patent was granted that Edison and his team discovered that a carbonized bamboo filament could last over 1200 hours.

This discovery marked the beginning of commerically manufactured light bulbs and in 1880, Thomas Edison’s company, Edison Electric Light Company begain marketing its new product.

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