Our speed was now twenty-five miles an hour. It may be well understood that Ned Land, to his great disgust, was obliged to renounce his intended flight. He could not launch the pinnace, going at the rate of twelve or thirteen yards every second. To quit the _Nautilus_ under such conditions would be as bad as jumping from a train going at full speed—an imprudent thing, to say the least of it. Besides, our vessel only mounted to the surface of the waves at night to renew its stock of air; it was steered entirely by the compass and the log. I saw no more of the interior of this Mediterranean than a traveller by express train perceives of the landscape which flies before his eyes; that is to say, the distant horizon, and not the nearer objects which pass like a flash of lightning. We were then passing between Sicily and the coast of Tunis. In the narrow space between Cape Bon and the Straits of Messina the bottom of the sea rose almost suddenly. There was a perfect bank, on which there was not more than nine fathoms of water, whilst on either side the depth was ninety fathoms. The _Nautilus_ had to manœuvre very carefully so as not to strike against this submarine barrier. I showed Conseil, on the map of the Mediterranean, the spot occupied by this reef. “But if you please, sir,” observed Conseil, “it is like a real isthmus joining Europe to Africa.” “Yes, my boy, it forms a perfect bar to the Straits of Lybia, and the soundings of Smith have proved that in former times the continents between Cape Boco and Cape Furina were joined.” “I can well believe it,” said Conseil. “I will add,” I continued, “that a similar barrier exists between Gibraltar and Ceuta, which in geological times formed the entire Mediterranean.” “What if some volcanic burst should one day raise these two barriers above the waves?” “It is not probable, Conseil.” “Well, but allow me to finish, please, sir; if this phenomenon should take place, it will be troublesome for M. Lesseps, who has taken so much pains to pierce the isthmus.” “I agree with you; but I repeat, Conseil, this phenomenon will never happen. The violence of subterranean force is ever diminishing. Volcanoes, so plentiful in the first days of the world, are being extinguished by degrees; the internal heat is weakened, the temperature of the lower strata of the globe is lowered by a perceptible quantity every century to the detriment of our globe, for its heat is its life.” “But the sun?” “The sun is not sufficient, Conseil. Can it give heat to a dead body?” “Not that I know of.” “Well, my friend, this earth will one day be that cold corpse; it will become uninhabitable and uninhabited like the moon, which has long since lost all its vital heat.” “In how many centuries?” “In some hundreds of thousands of years, my boy.” “Then,” said Conseil, “we shall have time to finish our journey—that is, if Ned Land does not interfere with it.”