Posted by: Prospector PJ4 FEB 2010
National Inventors’ Day is held in the US on 11 February, the anniversary of the birth of Thomas Edison, perhaps the most prolific inventor ever.
Some other countries celebrate their own inventors’ days in honour of famous national inventors. Argentina, for example, holds its inventors’ day on 29 September to mark the birth of László József Bíró, inventor of the ballpoint pen. And, as Bystander wrote (PJ, 7 November 2009, p515), Germany, Austria and Switzerland celebrate National Inventors’ Day on 9 November, the birthday of the Austrian-born Hollywood actress Hedy Lamarr, co-inventor of the frequency-hopped spread spectrum in 1942.
Edison was one of the first inventors to apply mass production techniques to the art of invention, helping him to accumulate 1,093 US patents in his name. He is most commonly linked with the incandescent light bulb, but he was also responsible for the phonograph, the motion picture camera and the carbon microphone.
Apart from the phonograph, which was the first device to record and reproduce sounds, most of Edison’s inventions were improvements to existing products. Even his light bulb was not an original invention. It had already been developed by a number of others, including British pharmacist Joseph Swan, as reported by Didapper (PJ, 2 August 2008, p144). Edison’s patent, a year after Swan’s, was for the first commercially practical, long-lasting and cost-effective incandescent bulb.
Edison first demonstrated his incandescent light bulb in 1879. To capitalise on his invention, he patented a system for electricity distribution the following year. The Edison Illuminating Company began supplying 110 volt direct current to 59 customers in New York in 1882 and, by 1887, there were 121 Edison power stations in the US.
But direct current had the serious limitation that power plants could only send it about a mile before the electricity began to lose power. So when George Westinghouse introduced his high-voltage alternating current system, which could carry electricity hundreds of miles with little loss of power, Edison’s electricity monopoly came under threat.
He subsequently waged an unsuccessful propaganda “war of currents”, which included electrocuting an elephant in 1903, to “prove” the dangers of alternating current. Westinghouse’s superior system soon took over, although the direct current service to downtown New York City was not discontinued until 2007.