fixer27 said:
Tesla my have invented AC/DC current but the first lines were marketed
and installed by Edison and the switch over to AC was also pushed by
Edison. Every building used to have dynamo in the basement. Edison
helped to remove those inefficent system and replace them with Tesla's
inventions. The marketer proved greater that the inventor (Again).
Actually, like many great accomplishments, it's not as simple as one man. For the truly interested, there's a great book called
Electrifying America by David E. Nye that documents it well. Henry Ford was actually involved this too. Edison's company, General Electric, had a huge role, but so did many others.
Edison, as previously noted, wasn't actually the inventor of many of the things he's credited with. There's a great book that I can't remember the author of and can't find my copy of called
The Unsung Heros of Menlow Park which tells a lot of those stories.
The lightbulb was actually a French invention, but the French couldn't get 'em to last very long. After trying virtually every known substance on the face of the earth as a filiment, Edison sat down and asked, "Why does everything burn up?" It was one of his assistants who conjectured that they burned out because of oxygen in the bulb. Edison then embarked on a program to evacuate the bulbs building bigger and bigger and more and more powerful pumps and pushing his glass shop for stronger and stronger bulbs. Then, one day, one of his assistants re-setup one of the old, weak pumps and took one of the old, weak bulbs from a discarded box and did so in a very careful was as to attract Edison's attention. He proceeded to make a bulb. He turned the bulb on and put it where everyone, especially Edison, could see it. And then he went for a long lunch. And the bulb burned and burned and burned... much longer than any bulb yet made. When he returned, Edison demanded to know the secret, but the man wouldn't tell. Edison almost strangled him to death before he showed his idea. Most bulbs have two wires sticking out of them and one filiment between them. The man made a bulb with three wires and two filiments. He lightly evacuated it. Then he deliberately burned out the first filiment thus burning up the air in the bulb and replacing it with combustion byproduct gas. Becasue the bulb had only a slight vacuum, the glass didn't need to be very strong. But because the oxygen inside had been burned up already, the second filiment was free to burn in an oxygen-free environment. Brilliant!
And so they went into production. After the first filiment was burned out, the third wire was cut off from the outside of the bulb. It could still be seen sticking up inside the bulb, but there was no remaining external connection to it.
Edison had sample bulbs delivered to his lab frequently before the first filiment was burned for quality testing. It was in testing one of these samples that he noticed that he could get a current to flow from the extra wire to the remaining filiment, but not the other way. He was puzzled by this. How could current flow when there was no electrical connection? And why would current only flow in one direction? But he failed utterly to realize what he had. It would be John Ambrose Fleming who would invent the vacuum tube and usher us from electricity to electronics.
Daylight Savings Time was not one of his better ideas though. 
