Sommeiller, Germain

SUBJECT AREA: Civil engineering, Mining and extraction technology

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b. 15 March 1815 St Jeoire, Haute-Savoie, France

d. 11 July 1874 St Jeoire, Haute-Savoie, France

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French civil engineer, builder of the Mont Cénis tunnel in the Alps.

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Having been employed in railway construction in Sardinia, Sommeiller was working as an engineer at the University of Turin when, in 1857, he was commissioned to take charge of the French part in the construction of the 13 km (8 mile) tunnel under Mont Cénis between Modane, France, and Bardonècchia, Italy. This was to be the first long-distance tunnel through rock in the Alps driven from two headings with no intervening shafts; it is a landmark in the history of technology thanks to the use of a number of pioneering techniques in its construction.

As steam power was unsuitable because of the difficulties in transmitting power over long distances, Sommeiller developed ideas for the use of compressed-air machinery, first mooted by Daniel Colladon of Geneva in 1855; this also solved the problems of ventilation. He also decided to adapt the principle of his compressed-air ram to supply extra power to locomotives on steep gradients. In 1860 he took out a patent in France for a combined compressor-pump, and in 1861 his first percussion drill, mounted on a carriage, was introduced. Although it was of little use at first, Sommeiller improved his drill through trial and error, including the use of the diamond drill-crowns patented by Georges Auguste Leschot in 1862. The invention of dynamite by Alfred Nobel contributed decisively to the speedy completion of the tunnel by the end of 1870, several years ahead of schedule.

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Further Reading

A.Schwenger-Lerchenfeld, 1884, Die Überschienung der Alpen, Berlin; reprint 1983, Berlin: Moers, pp. 60–77 (explains how the use of compressed air for rock drilling in the Mont Cénis tunnel was a complex process of innovations to which several engineers contributed).

W.Bersch, 1898, Mit Schlägel und Eisen, Vienna: reprint 1985 (with introd. by W.Kroker), Dusseldorf, pp. 242–4.

WK