the weight of the carriages and waggons, for it is obvious that if a vehicle weighing, say, 3 tons (we take the figure at random) will carry safely, efficiently, and without strain upon any part of it, a given load, any weight beyond 3 tons is surplusage—not only unnecessary but most injurious. If anything tarnish the success of the Mont Cenis Railway, it is more likely to be from this cause than from any other that we are acquainted with, as the fact is undoubted that the weights are much in excess of what are required for the tractive power of the engines or for the safe conveyance of the loads that will be placed in the carriages and waggons behind them.[122] CHAPTER XII. TUNNELS, ANCIENT AND MODERN. It is hardly necessary to say that the great rival to the Mont Cenis or Summit Railway is the railway that is to be laid through the tunnel, which, in the official documents of both France and Italy is denominated “The Great Tunnel of the Alps.” But before we enter upon the description of this tunnel, an account of subterraneous construction from the earliest period we have been able to trace tunnels, may not be uninteresting. Tunnelling through hills and mountains is not exactly “as old as the hills,” but the practice, nevertheless, is of great antiquity.[123] Yet, the oldest tunnel of which we have record was neither through hill nor mountain, but was carried beneath the course of the River Euphrates. This happened no less than 4,812 years ago, for it was at that time that Semiramis was appointed by her dying husband, Ninus, King of Assyria, Regent and guardian to their only child, the infant Ninias. The royal widow, according to Diodorus the Sicilian, the most trustworthy historian of antiquity, who has written of the peoples that existed earliest after the world’s creation, commenced her reign 2,944 years before the birth of Christ, and immediately afterwards, the building of Babylon was begun, by two millions of men, who had been collected, by regal command, from all parts of the empire. The mighty city was erected on the two sides of the Euphrates, on each bank of which was raised a palace of colossal proportions. These the Queen Regent connected together by “a passage under the river,[124] in the nature of a vault, from one palace to another, whose arches were built of firm and strong brick, and plastered all over on both sides with bitumen, four cubits thick. The walls of this vault were twenty bricks in thickness, and twelve feet high, and the breadth was fifteen feet. This piece of work was finished in 220 days, and the river flowing over the vault. Semiramis could thus go from one palace to the other without passing over the river. She made likewise two brazen gates at either end of the vault, which continued to the time of the Persian empire.” The passage was made, not by the process of tunnelling as we now understand it, but by first making enormous works for diverting