which was put in motion by steam. The machine was imperfect, and while experiments were being made with it (by means of compressed air), M. Sommeiller invented the boring-machine which is now used in the tunnel."
"The problem then appeared to be solved. The inventors joined themselves to M. Ranco—who had taken part in their experiments on the Genoa Railway—prepared a scheme, and presented it with confidence to the government, after having found out that they could compress air to a high pressure, that this air could be led from closed reservoirs and transmitted to great distances without a sensible diminution of its pressure, and that it could be employed to move the boring-machine which was intended to make the holes for blasting. A commission was appointed to examine the project, and its members satisfied themselves that the scheme was feasible. The Act of August 15, 1857, authorised the government to construct the section of the Victor Emmanuel Railway between Susa and Modane. MM. Grandis, Grattoni, and Sommeiller, were appointed to direct the works."
"M. Medail indicated the general direction of the tunnel between Modane and Bardonnêche. M. Maus drew his line a little more to the east, nearer to Modane. The engineers who direct the work have approached the latter course, and have selected that which seemed to them to be the shortest, the most easy to come out at, and, especially, the most convenient to lay out."
"It is needless to insist on the importance of the tracing of the course of the tunnel. It was necessary—1st, To establish upon the mountain a sufficient number of marks in order to determine the vertical plane passing through the axis of the gallery; 2. To measure exactly the distance between the two mouths; 3. To determine the difference of level between the two mouths, in order to arrange the gradients of the tunnel."
"These delicate operations were entrusted to MM. Borelli and Copello. M. Grandis undertook the control of the work."
"After the two mouths had been determined upon, they set out
