Tesla emigrated to the U.S.A. in 1884. During the first year he filed no less than 30 patents mostly in relation to the generation and distribution of A.C. mains electricity. He designed and built his 'A.C. Polyphase System' which generated three-phase alternating current at 25 Hz. One particular unit delivered 422 amperes at 12,000 volts. The beauty of this system was that the voltage could be stepped down using transformers for local use, or stepped up to many thousands of volts for transmission over long distances through relatively thin conductors. Edison's generating stations were incapable of any such thing. Tesla signed a lucrative contract with the famous railway engineer George Westinghouse, the inventor of the Westinghouse Air Brake which is used by most railways all over the world to the present day. Their generating station was put into service in 1895 and was called the Niagara Falls Electricity Generating Company. It supplied power for the Westinghouse network of trains and also for an industrial complex in Buffalo, New York. After ten years Tesla began to experiment with high frequencies. The Tesla Coil which he had patented in 1890 was capable of raising voltages to unheard of levels such as 300,000 volts. Edison, who was still generating D.C., claimed A.C. was dangerous and to prove it contracted with the government to produce the first electric chair using A.C. for the execution of murderers condemned to death. When it was first used it was a ghastly flop. The condemned man moaned and groaned and foamed at the mouth. After four minutes of repeated application of the A.C.voltage smoke began to come out of his back. It was obvious that the victim had suffered a horribly drawn-out death. Tesla said he could prove that A.C. was not dangerous. He gave a demonstration of high voltage electricity flowing harmlessly over his body. But in reality, he cheated, because he had used a frequency of 10,000 cycles (10 kHz) at extremely low current and because of the skin effect suffered no harm. One of Tesla's patents related to a system of lighting using glass tubes filled with fluorine (not neon) excited by H.F.voltages. His workshop was lit by this method. Several years before Wilhelm Roentgen demonstrated his system of X-rays Tesla had been taking photographs of the bones in his hand and his foot from up to 40 feet away using H.F.currents.