And Conseil, reassured, returned to the study of the bank, which the _Nautilus_ was skirting at a moderate speed. During the night of the 16th and 17th February we had entered the second Mediterranean basin, the greatest depth of which was 1,450 fathoms. The _Nautilus_, by the action of its screw, slid down the inclined planes and buried itself in the lowest depths of the sea. On the 18th of February, about three o’clock in the morning, we were at the entrance of the Straits of Gibraltar. There once existed two currents: an upper one, long since recognised, which conveys the waters of the ocean into the basin of the Mediterranean; and a lower counter-current, which reasoning has now shown to exist. Indeed, the volume of water in the Mediterranean, incessantly added to by the waves of the Atlantic and by rivers falling into it, would each year raise the level of this sea, for its evaporation is not sufficient to restore the equilibrium. As it is not so, we must necessarily admit the existence of an under-current, which empties into the basin of the Atlantic through the Straits of Gibraltar the surplus waters of the Mediterranean. A fact indeed; and it was this counter-current by which the _Nautilus_ profited. It advanced rapidly by the narrow pass. For one instant I caught a glimpse of the beautiful ruins of the temple of Hercules, buried in the ground, according to Pliny, and with the low island which supports it; and a few minutes later we were floating on the Atlantic. CHAPTER VIII VIGO BAY The Atlantic! a vast sheet of water whose superficial area covers twenty-five millions of square miles, the length of which is nine thousand miles, with a mean breadth of two thousand seven hundred—an ocean whose parallel winding shores embrace an immense circumference, watered by the largest rivers of the world, the St. Lawrence, the Mississippi, the Amazon, the Plata, the Orinoco, the Niger, the Senegal, the Elbe, the Loire, and the Rhine, which carry water from the most civilised, as well as from the most savage, countries! Magnificent field of water, incessantly ploughed by vessels of every nation, sheltered by the flags of every nation, and which terminates in those two terrible points so dreaded by mariners, Cape Horn and the Cape of Tempests. The _Nautilus_ was piercing the water with its sharp spur, after having accomplished nearly ten thousand leagues in three months and a half, a distance greater than the great circle of the earth. Where were we going now, and what was reserved for the future? The _Nautilus_, leaving the Straits of Gibraltar, had gone far out. It returned to the surface of the waves, and our daily walks on the platform were restored to us.