He invented the electric chair as a marketing gimmick to attempt to convince the public that alternating current was dangerous compared to his sucky direct current. The prototype was used on a criminal that I feel sorry for - it could not do the job and was reported as 'hours of forlorn moaning' before the poor guy finally died. Sick Edison kept hitting him with progressively more and more current, but severely underestimated the level needed.

This was all so Edison could continue his mini-empire of local DC-based electric monopolies, as he feared Tesla's abilities to transmit AC over very long distances through extremely arcane devices known as 'transformers' which Edison's small mind could not grok.

We continue to use, to this day, AC running at 60 Hz, due to Edison's twisted marketing. While all electricity is dangerous in foolish hands, 60 Hz is one of the most dangerous base frequencies for electricity due to it being near the operating frequency for nerve cells. It takes nearly 100 times the electricity at 14 Hz to kill a man than it does at the peak dangerousity of 60Hz.

It's sick that Edison is taught to the children to be some kind of genius hero, when in actually he was a scheming, theiving, murderer. And Telsa is nearly forgotten. Primarily for his invention that would have allowed for nearly free electrical generation by installing very very tall towers around the planet which would use the Earth's magnetic field to generate pollutionless electricity! That was severely beaten down by the energy moguls of the late 1800's - Edison and the Rockefellers (Standard Oil) who would have lost millions/billions. Standard Microsoftian practices - look how much work they are putting into knocking down Linux - a free OS that can do nothing but make the world better at the expense of some of Mr Bills fortune. Same shit, different day!