Thomas Alva Edison - Not The Inventor Of The Light Bulb
Despite popular belief, Thomas Alva Edison was clearly not the inventor of the incandescent light bulb, there were too many inventors prior to Edison's involvment in the development of the light bulb for him to make that claim. Edison simply improved upon the ideas of others.
What is clear though, is that Edison was probably the single most important participant in creating what we commonly know as the modern light bulb (possibly with the exception of Sir Humphry Davy who started the whole thing).
Edison's life story is far too extensive to go into great detail here, needless to say he was one of the most prolific inventors of his, or any other time. What we are concerned with here is his contribution to improving the incandescent light bulb.
In 1978 Edison started to look in earnest at the problems involved with creating a practical incandescent light bulb. Up till this point previous attempts to acheive an electric lamp that had a lifespan long enough to be commercially viable had failed. Sir Joseph Wilson Swan, in that same year, had been successful in creating a bulb that lasted approximately 13.5 hours using a carbonised paper filament.
Edison and his team experimented with hundreds, if not thousands of different materials to use as the filament and at one point thought he had found the solution using a platinum filament in a vacuum. This had been tried before, but the problem had previously been that the platinum would quickly melt. Edison's solution was to include a heat switch which would cut the power if the filament got too hot. However, this made the bulb unusable as it would constantly flicker on and off as the temperature rose and fell.
Edison then took on a promising young physicist named Francis Upton from Princeton University. He suggested they start looking at the patents of other inventors whom had tried to solve the same problems and learn from their experiences. Of most interest were the patents of Sir Joseph Swan and a patent Edison allegedly bought from Henry Woodward and Matthew Evans.
They soon realised that what they were looking for was a substance that had a high electrical resistance, meaning that there was a lot of 'friction' generated when electricity tries to pass through it. It is this resistance that causes the material to heat up and start glowing and the higher the resistance, the less electricity is required to get it to this point.
This instantly narrowed down the materials they needed to test and Edison's team soon discovered that carbonised Japanese bamboo provided them with just the qualities they needed. Edison aquired an improved model of the Sprengel vacuum pump which enabled him to create a better quality vacuum than had previously been possible.
In 1979 this combination of new filament and an improved oxygen-free vacuum meant that Edison could create a bulb that burned for approximately 40 hours. He then discovered that by changing the shape of the filament to a horseshoe he could get the bulb to burn for 100 hours and with further experimentation he was soon able to increase the lifespan of his bulb to 1500 hours.
At last, the world had a commercially viable incandescent electric light bulb.
This break-through, in turn, made electric power plants and supply networks a realistic possibility. Whereas previously the demand for electricity had not been enough to warrant investments in this area, the desire from the masses of electric light bulbs turn this situation on it's head.
By 1882 Edison had created the worlds first power station on Pearl Street, Manhattan and was supplying electricity to one square mile of New York.
And the rest, as they say, is history.
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