“Under the sea there is ground, the same as under the waters of a lake or stream. Under-sea ground is uneven, just as dry land is uneven. In certain parts it is hollowed out into deep chasms that can scarcely be sounded; in others it is cut up with mountain-chains, the highest points of which come up above the level of the water and form islands; in still others, it extends in vast plains or rises up in plateaus. If dry, it would not differ from the continents.” “Then the depth is not the same everywhere?” “In no wise. To measure the depth of the water, a plummet attached to one end of a very long cord is cast into the sea; the length of line unrolled by the plummet in its fall indicates the depth of the water. “The greatest depth of the Mediterranean appears to be between Africa and Greece. In these parts, in order to touch bottom, the lead unwinds 4000 or 5000 meters of line. This depth equals the height of Mont Blanc, the highest mountain in Europe.” “So if Mont Blanc were set down in this hollow,” was Claire’s comment, “its summit would only just reach the surface of the water.” “There are deeper places than that. In the Atlantic, south of the banks of Newfoundland, one of the best spots for cod-fishing, the lead shows about 8000 meters. The highest mountains in the world, in Central Asia, are 8840 meters high.” “Those mountains would come up above the surface of the water in the place you spoke of, and would form islands 850 meters in height.” “Finally, in the seas about the South Pole there are places where the lead shows 14,000 or 15,000 meters of depth, or nearly 4 leagues. Nowhere has the dry land any such altitudes. “Between these fearful chasms and the shore where the water is no deeper than the thickness of one’s finger, all the intermediate degrees may be found, sometimes varying gradually, sometimes suddenly, according to the configuration of the ground underneath. On one shore the sea increases in depth with frightful rapidity. That shore is, then, the top of an escarpment of which the sea washes the base. On another it increases little by little, and one must go a long distance to attain a depth of a few meters. There the ocean bed is a plain, sloping almost imperceptibly, in continuation of the terrestrial plain. “The average depth of the ocean appears to be from six to seven kilometers; that is to say, if all the submarine irregularities were to disappear and give place to a level bed, like the bottom of a basin made by man, the seas, while preserving on the surface their present extent, would have a uniform layer of water of from 6000 to 7000 meters in depth.” “I get rather bewildered with all these kilometers,” complained Emile. “Never mind; I begin to understand that there is a great deal of water in the sea.”