But the grandest tunnel of ancient Italy is the underground canal constructed by the orders of the Emperor Claudius to draw off the waters of the lake then called Fucinus, now Celano, into the River Siris. This stupendous work, three miles long, and nowhere less than twenty feet high, required the labour of 30,000 men for eleven years to accomplish. It has several shafts as in modern tunnels; it is now in a sound state, having been solidly repaired only a few years ago. In the second volume of _La Vie de Cæsar_, by the Emperor Napoleon III., pages 412, _et seq._, (English edition) will be found the account of the siege of Uxellodum (_Puy d’Issolu_, near Vayrac), the capture of which by Julius Cæsar, U.C., 703, put him in complete possession of Gaul. The town, surrounded on all sides by steep rocks, was, even without being defended, difficult of access to armed men. It was also well provisioned, but, as its water supply was derived from an abundant spring which arose at the foot of the wall of the town, 300 feet from the channel of the River Tourmente, “Cæsar resolved,” says his Imperial historian, “to drain this spring, and for this purpose he did not hesitate to attempt a laborious undertaking. Opposite to the point where the spring rose, he ordered covered galleries to be pushed forward against the mountain, and, under protection of them, a terrace to be raised. Although these works were attended with great danger and fatigue, they were vigorously persevered in. At the same time, a subterranean excavation on a lower plane than the fountain, and running from the galleries, was made. This work, carried on, free from all danger, was executed without being perceived by the Gauls; the terrace attained a height of sixty feet, and was surmounted by a tower of ten stories, which, without equalling the elevation of the wall of the town, a result it was impossible to attain, still commanded the fountain. Its approaches, battered by engines from the top of the tower, became inaccessible; in consequence of this, many men and animals in the place died of thirst. Nevertheless, the Gauls did not yield. At last, the subterranean gallery having reached the veins of the spring, they were taken and turned aside. The besieged seeing the fountain all at once dried up, believed, in their despair, that it was an intervention of the gods: they submitted to necessity, and surrendered.” Researches made for the purposes of the _Vie de Cæsar_, by M. J. B. Cessac, assisted subsequently by the Permanent Commission of the Department du Lot, have brought this tunnel fully into view. It was carried through the marl; and the proof that the Roman soldiers had not boring tools suited for penetrating rock is afforded by the fact that, when they came upon it, they deviated in the expectation that they would come upon the tufas which, formed by the waters, would necessarily lead towards the spring. The Roman soldiers were right in their expectations.