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
Carbon button lamp Carbon button lamp The carbon button lamp is a single-electrode incandescent lamp invented by Nikola Tesla. A carbon button lamp contains a small carbon sphere positioned in the center of an evacuated glass bulb. This type of lamp must be driven by high-frequency alternating current, and depends on an electric arc or perhaps a vacuum arc to produce high current around the carbon electrode. The carbon electrode is then heated to incandescence by collisions by ions which constitute the electric current. Tesla found that these lamps could be used as powerful sources of ionizing radiation. In February, 1892, Tesla gave