“Why?” I replied, looking fixedly at Ned Land, whose meaning was easy to guess. “Because,” I added, “if my surmises are correct, and if I have well understood the Captain’s existence, the Nautilus is not only a vessel: it is also a place of refuge for those who, like its commander, have broken every tie upon earth.” “Perhaps so,” said Conseil; “but, in any case, the Nautilus can only contain a certain number of men. Could not you, sir, estimate their maximum?” “How, Conseil?” “By calculation; given the size of the vessel, which you know, sir, and consequently the quantity of air it contains, knowing also how much each man expends at a breath, and comparing these results with the fact that the Nautilus is obliged to go to the surface every twenty-four hours.” Conseil had not finished the sentence before I saw what he was driving at. “I understand,” said I; “but that calculation, though simple enough, can give but a very uncertain result.” “Never mind,” said Ned Land urgently. “Here it is, then,” said I. “In one hour each man consumes the oxygen contained in twenty gallons of air; and in twenty-four, that contained in 480 gallons. We must, therefore find how many times 480 gallons of air the Nautilus contains.” “Just so,” said Conseil. “Or,” I continued, “the size of the Nautilus being 1,500 tons; and one ton holding 200 gallons, it contains 300,000 gallons of air, which, divided by 480, gives a quotient of 625.