Captain Tyler, whilst instituting a comparison between the cost of the construction and working of the Mont Cenis Over-ground Railway with these costs upon the railway through the Great Tunnel of the Alps, calls especial attention to the fact that the former is only laid down on a road-bed already in existence, as a temporary (that is if we can accept temporary as an exact translation of _provisoire_) line, whilst that through the tunnel is permanent. But keeping this point in view, the report of Mr. James Brunlees, C.E., the distinguished engineer of the Mont Cenis Railway Company, shows its cost to be (including the necessary engines and other rolling stock) a little under £8,000 a mile, whilst he asserts that the Tunnel line will probably cost, including interest at 6 per cent, during construction, but _not_ the cost of special engines and other rolling stock, £7,000,000, or £140,000 a mile. As the cost of the tunnel and its accessories is dealt with subsequently at full length, we need only here remark that Captain Tyler considers the cost of an over-ground _permanent_ Fell line, laid down on an already existing Alpine roadway, with the ordinary 4 feet 8½-inch gauge, and with curves of radii varying from 150 to 180 yards, should not exceed three times the cost of the present provisional road, or about £21,000 a mile. We are disposed to concur completely in this estimate, provided the additional width that it would be necessary to give to the roadway could be obtained by excavating from the _inner_ side of the road, and not by widening it on its outer side—the side of the precipice—for this latter could only be effected by the construction of numerous solid and very expensive abutments in masonry, requiring great tact, nicety and judgment in their adjustment. Captain Tyler concludes his report to the Board of Trade as follows:— “As the results of my observations and experiments, I have to report, in conclusion, that this scheme for crossing the Mont Cenis is, in my opinion, practicable, both mechanically and commercially, and that the passage of the mountain may thus be effected, not only with greater speed, certainty, and convenience, but also with greater safety than under the present arrangements. Few would, in the first instance, either contemplate or witness experiments upon such steep gradients and round such sharp curves on the mountain side, without a feeling that much extra risk must be incurred and that the consequences of a fractured coupling or a broken tire, or a vehicle leaving the rails, would on such a line be considerably aggravated. “But there is an element of safety in this system of locomotive working which no other railway possesses.