Arc lamp Arc lamp An arc lamp or arc light is a lamp that produces light by an electric arc (also called a voltaic arc). The carbon arc light, which consists of an arc between carbon electrodes in air, invented by Humphry Davy in the first decade of the 1800s, was the first practical electric light. It was widely used starting in the 1870s for street and large building lighting until it was superseded by the incandescent light in the early 20th century. It continued in use in more specialized applications where a high intensity point light source was needed, such as
Automatic lamp changer with high precision. The device automatically detects when the currently active lamp has ceased to function and moves the next lamp into place. The automatic lampchanger was invented by Charles Wallace and patented in 1928. This original model held two headlight lamps from a Model T automobile. The United States Lighthouse Service had these in common use by the 1930s, as they moved to convert all navigational lights to electricity. Lamp changers in current use may have two, four, or six lamps and use either a spring-loaded mechanism or an electric motor to change lamps when required. They are used