Long before the incandescent electric light bulb was invented, arc lamps had given birth to the science of electric lighting. In the early 1800s, when the first large batteries were being built, researchers noticed that electric current would leap across a gap in a circuit, from one electrode to the other, creating a brilliant light. Sir Humphry Davy is credited with discovering this electric arc and inventing the first arc lamp, which used carbon electrodes.

Yet the electric arc lamp remained a curiosity for decades. Many scientists gave public demonstrations of arc lighting, and the invention of automatic controls in the 1840s made it possible for arc lamps to be used in special applications such as lighthouses, theaters, and microscopes. But arc lamps still relied on expensive batteries or generators as their source of power. Then a flurry of inventions brought arc lighting into widespread use...