George Westinghouse was an American inventor and manufacturer noted for his prolific contributions to railroads and electric power generation and transmission. He is generally regarded as a visionary whose ideas transformed the safety and services of the American railroad and electricity industries. He formed and directed more than 60 companies to market his and others' inventions during his lifetime. His electric company became one of the greatest electric manufacturing organizations in the United States. He invented the air brake (1869), one of the most important safety devices in railroad history. This device enabled trains to be stopped with fail-safe accuracy by the locomotive engineer for the first time and was eventually adopted on the majority of the world's railroads. The hydroelectric development of Niagara Falls by Westinghouse (1896) inaugurated the practice of placing generating stations far from urban center of demand. It also demonstrated the superiority of alternating current over direct current for long distance transmission. He also patented devices for the transmission of natural gas, and telephone switching, among many others.