I had barely gotten up from my passably hard mattress when I felt my mind clear, my brain go on the alert. So I began a careful reexamination of our cell. Nothing had changed in its interior arrangements. The prison was still a prison and its prisoners still prisoners. But, taking advantage of our slumber, the steward had cleared the table. Consequently, nothing indicated any forthcoming improvement in our situation, and I seriously wondered if we were doomed to spend the rest of our lives in this cage. This prospect seemed increasingly painful to me because, even though my brain was clear of its obsessions from the night before, I was feeling an odd short-windedness in my chest. It was becoming hard for me to breathe. The heavy air was no longer sufficient for the full play of my lungs. Although our cell was large, we obviously had used up most of the oxygen it contained. In essence, over an hour’s time a single human being consumes all the oxygen found in 100 liters of air, at which point that air has become charged with a nearly equal amount of carbon dioxide and is no longer fit for breathing. So it was now urgent to renew the air in our prison, and no doubt the air in this whole underwater boat as well. Here a question popped into my head. How did the commander of this aquatic residence go about it? Did he obtain air using chemical methods, releasing the oxygen contained in potassium chlorate by heating it, meanwhile absorbing the carbon dioxide with potassium hydroxide? If so, he would have to keep up some kind of relationship with the shore, to come by the materials needed for such an operation. Did he simply limit himself to storing the air in high-pressure tanks and then dispense it according to his crew’s needs? Perhaps. Or, proceeding in a more convenient, more economical, and consequently more probable fashion, was he satisfied with merely returning to breathe at the surface of the water like a cetacean, renewing his oxygen supply every twenty-four hours? In any event, whatever his method was, it seemed prudent to me that he use this method without delay. In fact, I had already resorted to speeding up my inhalations in order to extract from the cell what little oxygen it contained, when suddenly I was refreshed by a current of clean air, scented with a salty aroma. It had to be a sea breeze, life-giving and charged with iodine! I opened my mouth wide, and my lungs glutted themselves on the fresh particles. At the same time, I felt a swaying, a rolling of moderate magnitude but definitely noticeable. This boat, this sheet-iron monster, had obviously just risen to the surface of the ocean, there to breathe in good whale fashion. So the ship’s mode of ventilation was finally established.