Type of lamp
Typr of lamp
arco elettrico
Electric arc.
The arc-lamp consists of a pair of carbon rods , or electrodes, in contact at pointed ends. Electric current is sent through them, and the electrodes are pulled slightly apart. Instantly a brilliant arc appears between the carbon points.
The electric current makes the arc glow by vaporizing enough carbon to bridge the gap.

In big towns gas lighting started in 1812 but improved only in 1886 by the Wolsbach's gas mantle invention.
Humphry Davy was the first man to attempt to obtain light from elecricity. In 1802 presented his carbon-arc lamp which made a white and brilliant light.
The electric energy produced by batteries was too expensive and the inventors weren't stimulated.
By the Gramme's dynamo (1870) all changed. The first electric lamps were installed in Swan house at Gateshead-on-Tyne and after ( december 1880) in the Sir William Armstrong house at Rothbury, the electric current was produced by an hydraulic turbine. It seems that this was the first water-power plant in England. Also Lord Kelvin installed the electric light in his house.
At the end of 1881 the Swan lamps were installed in the Savoy Theatre of London (824 lamps for the stage and 370 for the other parts of the theatre).
Staite presented his lamp with a metallic filament in 1847 at Sunderland, Durham. Among the audience there was oseph Swan who will invent the carbon filament.
Staite made the first clockwork to keep constant the distance bewtween the electrodes of arc-lamps.

lampada di Staite
The lamp of Staite - 1847 -
Lampada di W.de La Rue (1820).
The lamp of W.de La Rue (1820).
William de La Rue (1815-1889) and Sir William Grove (1811-1896) were the first to understand that the filament would be heated in a glass bulb in absence of oxygen.
The lamp of de La Rue had a platinum filament that begins to give out light at temperatures near his melting-point.
This is the motive of his brief duration.

Patented in 1857 this lamp was used in lighthouses, after the dynamo of Gramme (1870).

Lampada ad arco di Serrin.
The arc-lamp of Serrin.
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