The windows, as Cosmo had said, were so arranged that they afforded views on all sides. These views were, of course, restricted by the combined effects of the smallness of the windows and their great thickness; the inmates were somewhat like prisoners looking out of round ports cut through massive walls, but the range of view was much widened when they placed themselves close to the glasses, because the latter were in the form of truncated cones with the base outward. Glancing through the ports on the upper side of the bell Cosmo and his companions could perceive the huge form of the Ark, hanging like a cloud above them, but rapidly receding, while from the side ports they saw great shafts of azure sunlight, thrown into wonderful undulations by the disturbance of the water. These soon became fainter and gradually disappeared, but before the gloom of the depths settled about them they were thrilled by the spectacle of sharks and other huge fishes nosing about the outer side of the transparent cones, and sometimes opening their jaws as if trying to seize them. Most of the cone-shaped windows had flat surfaces, but a few were of spherical outline both without and within, and the radius of curvature had been so calculated that these particular windows served as huge magnifying lenses for an eye placed at a given distance. Once or twice a marine monster happened to place himself in the field of one of these magnifying windows, startling the observers almost out of their senses with his frightful appearance. There were also four windows reserved for projecting a searchlight into the outer darkness. The inner side of the bell corresponded in curvature with the outer, so that the adventurers had no flat flooring on any side to stand upon, but this caused little inconvenience, since the walls were abundantly provided with hand and foot holds, enabling the inmates to maintain themselves in almost any position they could wish. After a while they passed below the range of daylight, and then they turned on the searchlight. The storage batteries which supplied energy for the searchlight and the propellers served also to operate an apparatus for clearing the air of carbonic acid, and De Beauxchamps had carefully calculated the limit of time that the air could be kept in a breathable condition. This did not exceed forty-eight hours--but as we have seen they had no intention of remaining under water longer than twenty hours at the utmost.