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
Mercury-vapor lamp arc lamps operated in a mixture of air and mercury vapor at atmospheric pressure for lighting. The German physicist Leo Arons (1860–1919) studied mercury discharges in 1892 and developed a lamp based on a mercury arc. In February 1896 Herbert John Dowsing and H. S. Keating of England patented a mercury vapour lamp, considered by some to be the first true mercury vapour lamp. The first mercury vapor lamp to achieve widespread success was invented in 1901 by American engineer Peter Cooper Hewitt. Hewitt was issued on September 17, 1901. In 1903, Hewitt created an improved version that possessed higher