Type of lamp
Type of lamp
Lampda ad arco di Duboscq.
The arc-lamp of Duboscq.
This arc-lamp is famous because had been used by F.H.Holmes in South Foreland lighthouse, the first lightouse with an electric light (1857).
The lamps of this time were 36 volt and 1,3 ampere for a light of 16 candles. In 1905 has been adopted the filaments of tantalum and after those of wolfram. The lamps efficiency from 1,4 lumen/watt in 1881 becames 4 lumen/watt in 1900.
In this history it's right to speack of Alessandro Cruto (1847-1908) who lived in Piossasco (Turin). He founded in Alpignano (Turin) the first italian electric lamps establishment.
He wents only two year at school but was very interested in technical problems. In 1879 Cruto was present at a conference of Galileo Ferraris on the electric light.
Cruto, after many experiments, made a tubular, thin and homogeneous filament depositing carbon on a platinum thin wire which by the first flow of current volatilized, leaving only the carbon.
In 1881 a comparison between the lamps of Swan and the lamps of Cruto was propitious to Cruto.
Joseph Swan, after the Staite conference in 1847, made many attempts to build a filament that could glow satisfactorily.
In 1860 this filament burned out too rapidly.
The vacuum in the glass bulb was unsatisfacotry.
In 1865 Herman Sprengel invented his vacuum pump by mercury's vapor. By this pump were built the tubes for Crookes experiments.
Swan began agian his experiments and in 18 december 1878 presented at Newcastle-upon-Tyne an efficient electric lamp with a carbon filament. In 1881 Swan produced lamps in his manifacture.
He wouldn't patent his lamp because other inventors had thinked (before him) the same solution.
Lampada sperimentale di Swan - 1878
An experimental lamp of Swan - 1878 -
Lampada ad arco o candela di Jablochkoff - 1876 -The arc-lamp of Jablochkoff - 1876 -
Paul Jablochkoff, a russian man, was the first inventor of lamp to have commercial success. His "candle", a little arc-lamp which worked with a current of 8-9 ampere, not the usual 17-20 of other arc lamps.
In 1887 80 arc-lamps of Jablochkoff were installed at Grands Magazins du Louvre in Paris.
When Thomas Alva Edison (1847-1931) began to build electric lamps he thinked that the carbon filament wasn't the more suitable, but after many attempts, he renounced his old ideas and used a carbonized bamboo fiber (1880).
Edison, otherwise Swan, patented all his works.
In 1800 Edison sold 80.000 lamps with a threaded socket. In 1882 Edison sued the Swann society for patent's violation. The dispute was friendly decided by establishing the Edison and Swan Electricity Light Company Limited, registered in 1883.

lampade di EdisonLamps of Edison
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