All this magnitude had been designed and adapted for the realization of two chief ends—comfort and stability. We have perhaps heard enough about the arrangements for comfort; but the more vital matter had received no less anxious attention. Practically all of the space below the water-line was occupied by the heaviest things in the ship—the boilers, the engines, the coal bunkers and the cargo. And the arrangement of her bulkheads, those tough steel walls that divide a ship’s hull into separate compartments, was such that her designers believed that no possible accident short of an explosion in her boilers could sink her. If she rammed any obstruction head on, her bows might crumple up, but the steel walls stretching across her hull—and there were fifteen of them—would prevent the damage spreading far enough aft to sink her. If her broadside was rammed by another ship, and one or even two of these compartments pierced, even then the rest would be sufficient to hold her up at least for a day or two. These bulkheads were constructed of heavy sheet steel, and extended from the very bottom of the ship to a point well above the water-line. Necessarily there were openings in them in order to make possible communication between the different parts of the ship. These openings were the size of an ordinary doorway and fitted with heavy steel doors—not hinged doors, but panels, sliding closely in water-tight grooves on either side of the opening. There were several ways of closing them; but once closed they offered a resistance as solid as that of the bulkheads.