A practical electric light bulb

The story

The darkness of evening

For thousands of years, when the Sun set, life slowed down. To make light people used the fire in the hearth, torches, wax or tallow candles, oil lamps. In the 19th century gas lighting spread, in streets and in the homes of the rich: there were street lamps, lit one by one every evening by a man with a long pole, but gas was expensive, dirty and dangerous, because it could cause fires and poisoning. For big squares and theatres arc lamps were also used, which produced a very powerful light, but dazzling and too strong for homes.

After Volta's battery and the discoveries about electricity, many inventors thought of a softer, safer electric light: an incandescent lamp, in which an electric current makes a very thin wire, the “filament”, glow white-hot inside a glass bulb from which the air has been removed. Between 1840 and 1870 many attempts were made. The problem was to find a material that could withstand the heat without burning up and that would last long enough.

Two inventors, one light bulb

At the end of the 1870s two men, one in England and one in America, got there almost at the same time. The Englishman Joseph Swan, a chemist from Newcastle, built a lamp with a carbon filament in 1878–79 and showed it in public. The American Thomas Edison, the famous inventor of the phonograph, had founded a big laboratory at Menlo Park, in New Jersey, a real “invention factory”, where dozens of technicians and workers worked. His aim was a cheap, long-lasting and practical light bulb, and a whole system for bringing electricity into homes.

Edison and his collaborators tried thousands of materials: platinum, filaments of every kind, even hair and plant fibres. On 22 October 1879, according to tradition, a bulb with a carbonised cotton thread stayed lit for about thirteen and a half hours; soon afterwards one with a carbonised bamboo filament lasted more than a thousand hours. This was enough for a bulb that could be sold. Between 31 December 1879 and the first days of 1880, at Menlo Park, hundreds of visitors came to see the laboratory lit by light bulbs.

A network of light

The light bulb alone was not enough: electricity was needed. So Edison also invented the generators, the cables, the meters and the power station. On 4 September 1882, in New York, in Pearl Street, in the financial district, the first big commercial power station was opened: it brought light to a few dozen customers (59 according to many sources), including banks and newspapers, with about four hundred lamps. Soon afterwards the first districts of London were lit too.

And in Italy?

Italy was among the first too. In Milan, in 1883, the engineer Giuseppe Colombo, with Edison's backing, built in the city centre, at Santa Radegonda, near the Cathedral, the first power station in continental Europe. The Teatro alla Scala, on the evening of 26 December 1883, was the first big theatre to be lit by electric lamps, to the amazement of the audience. A few years later Rome and other Italian cities also began to have electric light.

The war of the currents

In the following years there was a technical contest: Edison used direct current, suited to short distances. Another inventor, Nikola Tesla, and the businessman George Westinghouse backed alternating current, which can be transmitted over long distances with less loss. After a long “war of the currents”, alternating current won, and was used at the Niagara power station in 1896.