After a few more words, Frank and Bob, who were ravenously hungry, hurried back to the hotel, and David and Clive, who were also, to tell the truth, equally hungry, resisted their appetites as well as they were able, and accompanied their guide to the Lake Albano. Most boys are familiar with the story of the Alban Lake; but for the benefit of those who may not have heard of it, or who, having heard, have forgotten, it may be as well to give a brief account of the famous tunnel, which was so very attractive to Clive and David. The city of Veii had been besieged for nine years, without success, by the Romans; and at length, in the tenth year, a great prodigy occurred, in the shape of the sudden rising of the waters of the Alban Lake to an extraordinary height, without any apparent cause. The Romans, in their bewilderment, sent a messenger to the oracle of Delphi to inquire about it. Before this messenger returned, they also captured a Verentine priest, who informed them that there were certain oracular books in Veii, which declared that Veii could never perish unless the waters of the Alban Lake should reach the sea. Not long afterwards the messenger returned from Delphi, who brought back an answer from the oracle at that place to the same effect. Upon this, the Romans resolved to draw off the waters of the lake so as to let them flow to the sea. Such an undertaking was one of the most laborious kind, especially in an age like that; but the Romans entered upon it, and worked at it with that extraordinary tenacity of purpose which always distinguished them. It was necessary to cut a tunnel through the mountain, through rock of the hardest possible description. But the same age had seen the excavation of other subterranean passages far larger than this, and in the same country, preeminently the Grotto of Posilipo, at Naples, and that of the Cumaean Sibyl, and at length it was accomplished. The people of Veii heard of it, and were filled with alarm. Ambassadors were sent to Rome, with the hope of inducing the Romans to come to some other terms less severe than the surrender of the city; but they were disappointed, and according to the legend, could only comfort themselves by announcing to the Romans a prophecy in the oracular books of Veii, to the effect that, if this siege should be carried through to the capture of the city, Rome itself should be taken by the Gauls soon after. This prophecy, however, had no effect. whatever upon the stern resolution of the Romans.