The man that changed the world
Had more than just knowledge...If Tesla's crack-pottery was a swimming pool his death ray would be the deep end. As early as 1916 Tesla was trotting out his idea for the ultimate weapon that would make war obsolete by providing nations with unopposible destructive power. Well, we got that little number in 1945 and look how well that worked out! While Tesla wasn't the first (or last) to come up with a scheme for building a death ray, he was the one with the credentials to get the press to take him seriously enough to interview him without breaking out in a case of the giggles.
Perhaps the best description of Tesla's death ray can be found in a 1937 New York Times Interview where he described how the borders of a country could be ringed by a series of towers, each of which contained his death ray generator. Any approaching foe by land, sea or air would be instantly detected and each tower, in the word of the times,
will send concentrated beams of particles through the free air, of such tremendous energy that they will bring down a fleet of 10,000 enemy airplanes at a distance of 250 miles from the defending nation's border and will cause armies of millions to drop dead in their tracksWhen put into operation, Dr. Tesla said, this latest invention of his would make war impossible. This death-beam, he asserted, would surround each country like an invisible Chinese wall, only a million times more impenetrable. It would make every nation impregnable against attack by airplanes or by large invading armies.
Yep. Chinese wall, Maginot Line; big static defences. What do they have in common? They don't work worth squat if anyone actually tried to breach them. Maybe Tesla's death ray was unstoppable, but the towers look very stoppable indeed, so I doubt there would would have had a sudden khaki surplus even if Tesla's device had worked.
Tesla tried to sell his death ray to Great Britain for $3,000,000 and promised to make the British Isles invulnerable within three months. Whitehall opted for radar and spitfires instead. He then tried to sell it to the League of Nations without success, actually managed to rook $25,000 out of the Soviet Union without delivering, and became convinced that the US government were making unsuccessful attempts to break into his hotel room.
What puts Tesla's death ray in a league of its own is that his design actually had competent, even inventive, engineering about it. His idea was to use a gigantic electrostatic generator run by one of his turbines to accelerate tiny particles of mercury until they became a stream of super high-powered bullets of several million volts. Since they were accelerated in a vacuum, Tesla needed a way to spit them out of the accelerator sphere without letting air in. He proposed to do this with a special nozzle which blew high-pressure air around an open tube leading to the evacuated sphere and acted like a constantly renewing plug to preserve the vacuum. What happen to the mercury stream after it left the nozzle and had to travel through the atmosphere was another matter that was never quite figured out.
Incidentally, by "particles" Tesla did not mean protons, neutron and the like, but tiny droplets. Tesla had little truck with atomic theory and for an electrician he had no time for electrons.