Light before the lamp
For most of history, artificial light meant fire: oil lamps, candles, torches, and from the early 1800s, gas. Electric light arrived as a laboratory curiosity before it was a useful tool. Its early story is not one of a single device but of a series of experiments that gradually became public lighting, with many people adding pieces along the way.
The arc
The first source of electric light bright enough to notice was the arc. When two pieces of carbon connected to a powerful battery are touched and then pulled slightly apart, current jumps the gap, and the carbon tips glow. Humphry Davy, working at the Royal Institution in London, is often credited with showing this to audiences in the first decade of the 1800s, using a very large battery. The light was extremely bright, but the battery was expensive and the carbons burned away, so the gap kept changing.
Arc lighting could not become practical until two problems were solved. One was a steady supply of electricity, which batteries such as the voltaic pile did not provide cheaply. The other was a mechanism to keep the carbon rods at the correct distance as they wore down.
Regulators and generators
In the middle of the 1800s several inventors created regulators, clockwork (borrowing ideas from mechanical clocks) or electromagnetic devices that moved the carbons closer together as they burned. At the same time, dynamos were developing, with major steps in the 1860s and 1870s by inventors such as Werner Siemens, Zénobe Gramme and others. Siemens, who also built early electric motors, was among the pioneers. Once dynamos, turned by steam engines or water power, could run for hours, arc lighting made economic sense for places that needed a great deal of light.
Some early installations are recorded at lighthouses. The South Foreland lighthouse in England is reported to have used an experimental electric arc light in the late 1850s, and other coastal stations tried electric arcs in the following decades. Powerful beams suited the job, and a coastal lighthouse was one of the few places that could justify the cost of a generator and a skilled attendant.
Jablochkoff candles
In 1876 a Russian engineer working in Paris, Pavel Jablochkov (often spelled Jablochkoff), patented a simpler arc lamp that placed two parallel carbon rods side by side with an insulating layer between them. This eliminated the need for a regulator, since the rods burned down together. The Jablochkoff candle was used on streets and in public places in Paris in 1878, including on a major avenue near the opera. Its weakness was its short burning time, and each candle had to be replaced after a few hours.
The candle’s fame helped spread the idea of electric street lighting. It also showed ordinary people, not only scientists, what the new light looked like: a cold, bluish-white glare very different from the yellow of gas.
Brush and others in America
In the United States, Charles Brush developed a dynamo and a regulated arc lamp in the 1870s. Brush arc lamps were installed in Cleveland in 1879, among other places, and by the early 1880s arc lighting systems lit streets, mills and shops across American cities. Such lamps were often placed on tall towers or poles to spread their light. Arc lamps had drawbacks. They were noisy, gave off fumes and needed frequent trimming, with workers replacing carbon rods. The light also was too harsh for most rooms.
Exhibitions and public interest
International exhibitions did a lot to publicize electric light. Paris hosted a major electrical exhibition in 1881 that showed dynamos, arc lamps and incandescent lamps side by side. Visitors could compare lighting types and see how they might serve cities and homes. Such events helped draw investors, engineers and city officials into the new industry.
The turn toward small lamps
The difficulty with arc lamps was that they were too bright and too large for indoor use. Gas, which could be turned down and divided among many small flames, was better suited to homes. Inventors therefore looked again at glowing filaments, a different route that dates from the same early period, and that could be sized like a gas flame. The development of incandescent lamps by Swan, Edison and others in the late 1870s opened the way to small electric lights that could be used almost anywhere.
Arc lighting did not disappear. It continued for large spaces, studio and stage lighting, searchlights and early film projection for many years. Carbon arc lamps were still used in some of these roles in the twentieth century.
Many contributors
The electric light was not one invention but a collection of linked developments: batteries, dynamos, regulators, carbon rods and finally small filament lamps. Credit is spread across Davy, Siemens, Gramme, Jablochkoff, Brush, Swan, Edison and many others. Where histories name a single person as the inventor of electric light, they are usually naming whoever took the final commercial step. For the broader story of the lamps that followed, see the separate accounts of the incandescent bulb.