The arc lamp was the first lamp used, and was already in extensive use by the late 1870s. Arc lamps have a high intensity blueish white light, and were used as streetlights or to light up large rooms, like factories. The arc lamp consists of two carbon electrodes, connected to a current limiter and a power source. When the electrodes are pushed together and then slowly parted, an electric arc will form through the ionized air between them. This arc heats the electrodes to several thousand degrees. The electrodes' tips will glow with an intense light.

The problem with these lamps is that the electrodes must constantly be readjusted, since the carbon vaporizes. The first lamps had to be manually adjusted, but later versions featured automatic adjustment and could even restart the arc, if it was put out.

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