The Engineer Jan. 9, 1880

Thomas Alva Edison, along with many other engineers, had spent several years developing a practical electric light. His predecessors responded to a report in the New York Herald that he finally accomplished what the other engineers were not capable of. A polite description would be that they were not convinced of his success.

The Engineer notes that when it comes to the description of Edison by the New York Herald, it does not believe that such a person even exists, and that it is surprising that Edison allows this newspaper to publish the allegations attributed to him.

“We refuse to believe the latter gentleman [Edison] can hold himself responsible for the sayings and doings of his prototype”

The author of the article about Edison´s light bulb was very skeptical, because such lamps had already been invented and manufactured, but they all failed in the past. He predicted that the lamp would not be able to burn continuously for at least four or five hours a night for half a year.

With hindsight you can see that the journal was quite right to be sceptical, because the version of the electric lamp described by the New York Herald was not the final one. Edison settled on a carbon fibre he derived from a bamboo fishing-rod as filament. He patented this light bulb and claimed to be its sole inventor.

When Edison began working on electric lighting, he used platinum wire filaments for hislight 3 lamps because the metal had a high melting point. But some basic research on the heating of platinum showed that air was absorbed into its pores as it was heating. This was weakening the metal and causing it to melt at lower temperatures. To solve this problem Edison placed the metal filament in a vacuum.

By using a vacuum he improved the performance of his lamps, but they were still too expensive for the electrical system he was designing. The next problem was that platinum had a low resistance to the electric current and in addition it was a very expensive metal. This meant that a power distribution system would need large and expensive copper-wire conductors.

Because Edison had developed such a good vacuum lamp, he was able to turn to carbon, which naturally had a high resistance but would burn up too rapidly in the atmosphere. Edison soon realized he could make carbon into a wire-like filament by using lampblack.

Further experiments with altered forms and composition of the substance were made and each experiment demonstrating that the inventor was Light 1upon the right track. If carbon was the solution, he still needed to find the best form of it and his experiments soon focused on plants like grasses which possessed long, uniform fibers that would form a long-lasting filament. Bamboo turned out to be the best material for the commercial lamp.

Edison continued to improve this design and filed for U.S. patent 0,223,898 for an electric lamp using “a carbon filament or strip coiled and connected to platina contact wires”.

But In fact it was the English engineer Joseph Swan who invented the first incandescent electrical light. Meanwhile Joseph Swan had also tried many different substances to build a working and long lasting filament, even including carbonised hairs from his beard. Later, he made an important innovation in discovering a process to form a conducting nitro-cellulose filament.  But, although Thomas Edison did not invent the first electric light bulb, he invented the first commercially practical incandescent light.

Light 2When Edison and Swan formed a joint-venture in 1883 to manufacture and market light bulbs, it was this cellulose filament that was used.

In later years the “Ediswan” factory at Ponders End in the north of London became an important industrial centre of major scientific significance, because not only the incandescent lamp was invented there but also the very first electronic valves were devised, which led to the development of Cathode Ray Tubes and many other inventions of the modern world.

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For five weeks in April/May this year we had a German placement student working with us at the collections.  During his time with us Daniel used The Engineer to research the work of Thomas Edison This is the second of three posts on Thomas Edison.
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