Science and technology in the United States finish. For example, the British engineer Joseph Swan built an incandescent electric lamp in 1860, almost 20 years before Edison. But Edison's light bulbs lasted much longer than Swan's, and they could be turned on and off individually, while Swan's bulbs could be used only in a system where several lights were turned on or off at the same time. Edison followed up his improvement of the light bulb with the development of electrical generating systems. Within 30 years, his inventions had introduced electric lighting into millions of homes. Another landmark application of scientific ideas to practical uses was the
War of the currents territory, paying a royalty to use the Stanley AC transformer patent, and allowing Westinghouse to use their Sawyer-Man incandescent bulb patent. Besides Thomson-Houston and Brush there were other competitors at the time included the United States Illuminating Company and the Waterhouse Electric Light Company. All of the companies had their own electric power systems, arc lighting systems, and even incandescent lamp designs for domestic lighting, leading to constant lawsuits and patent battles between themselves and with Edison. Elihu Thomson of Thomson-Houston was concerned about AC safety and put a great deal of effort into developing a lightning arrestor for high-tension