be) accomplished.[138] On the Italian half, the rock is throughout, schist, and the gradient, being only one in 2,000, or 2-8/25 per mile, all the elements for progress will continue to be, comparatively, as favourable as they have hitherto been; and even with a much less rapid rate of advance than on the French side, it requires no great gift of prophesy to “forecaste” that the boring machines from Italy will be ready to embrace those from France long before the latter shall have arrived at the midway point. But let it be understood that the works from the Italian side cannot go on a yard beyond midway,—first, on account of the gradient, which would dam up all the water percolating into the tunnel; second, because it would be impossible to keep the line of the tunnel, owing to the absence of all the external landmarks required for ensuring its correct direction. The embrace we have just referred to will take place 4,138 feet above the level of the sea, 1,645 above the level of St. Michel, 429 above the Modane entrance of the tunnel, but only 2-8/25 above that at Bardoneche, 2,360 above the level of Susa, about 5,360 feet _below_ the highest point of the Great Vallon Mountain, and 2,520 feet below the summit of the Mont Cenis Railway. What might have proved a source of great trouble and expense—water—has fortunately not as yet on any one occasion presented itself in a manner to cause alarm or even uneasiness. We need not therefore refer to this subject in any detail, but before proceeding to as important an element as any with which the tunnel is encompassed—cost—we had better state that the arch of the tunnel is a semicircle 25 feet 3½ inches at its base, 26 feet 3 at its broadest part, and 24 feet 7 inches high. (See diagram.)