How long we slept I do not know; but our sleep must have lasted long, for it rested us completely from our fatigues. I woke first. My companions had not moved, and were still stretched in their corner. Hardly roused from my somewhat hard couch, I felt my brain freed, my mind clear. I then began an attentive examination of our cell. Nothing was changed inside. The prison was still a prison,—the prisoners, prisoners. However, the steward, during our sleep, had cleared the table. I breathed with difficulty. The heavy air seemed to oppress my lungs. Although the cell was large, we had evidently consumed a great part of the oxygen that it contained. Indeed, each man consumes, in one hour, the oxygen contained in more than 176 pints of air, and this air, charged (as then) with a nearly equal quantity of carbonic acid, becomes unbreathable. It became necessary to renew the atmosphere of our prison, and no doubt the whole in the submarine boat. That gave rise to a question in my mind. How would the commander of this floating dwelling-place proceed? Would he obtain air by chemical means, in getting by heat the oxygen contained in chlorate of potash, and in absorbing carbonic acid by caustic potash? Or, a more convenient, economical, and consequently more probable alternative, would he be satisfied to rise and take breath at the surface of the water, like a cetacean, and so renew for twenty-four hours the atmospheric provision? In fact, I was already obliged to increase my respirations to eke out of this cell the little oxygen it contained, when suddenly I was refreshed by a current of pure air, and perfumed with saline emanations. It was an invigorating sea breeze, charged with iodine. I opened my mouth wide, and my lungs saturated themselves with fresh particles. At the same time I felt the boat rolling. The iron-plated monster had evidently just risen to the surface of the ocean to breathe, after the fashion of whales. I found out from that the mode of ventilating the boat. When I had inhaled this air freely, I sought the conduit-pipe, which conveyed to us the beneficial whiff, and I was not long in finding it. Above the door was a ventilator, through which volumes of fresh air renewed the impoverished atmosphere of the cell. I was making my observations, when Ned and Conseil awoke almost at the same time, under the influence of this reviving air. They rubbed their eyes, stretched themselves, and were on their feet in an instant. “Did master sleep well?” asked Conseil, with his usual politeness. “Very well, my brave boy. And you, Mr. Land?” “Soundly, Professor. But I don’t know if I am right or not; there seems to be a sea breeze!” A seaman could not be mistaken, and I told the Canadian all that had passed during his sleep. “Good!” said he; “that accounts for those roarings we heard, when the supposed narwhal sighted the _Abraham Lincoln_.” “Quite so, Master Land; it was taking breath.”