But the laws of physics shatter any such illusion and bid us paint a very different picture. Liquids are almost incompressible. The difference in density between the water at the surface of the sea and that at a depth of a mile is almost insignificant. As a matter of fact, at that depth the water would support only about half a pound more per cubic foot than at the surface. The pressure, however, would be enormous. Take the _Titanic_, for instance, which lies on the bed of the ocean in water two miles deep. It must endure a pressure of about two long tons on every square inch of its surface. Long before the vessel reached the bottom her hull must have been crushed in. Every stick of wood, every compressible part of her structure and of her cargo, must have been staved in or flattened. As a ship sinks it is not the water but the ship that grows progressively denser. The _Titanic_ must have actually gained in weight as she went down, and so she must have gathered speed as she sank. We may be certain, therefore, that every victim of Germany's ruthless U-boats that sank in deep water lies prone upon the floor of the sea. It matters not how or where it was sunk, whether it was staggered by the unexpected blow of the torpedo and then plunged headlong into the depths of the sea, or whether it lingered, mortally wounded, on the surface, quietly settling down until the waves closed over it. Theoretically, of course, a perfect balance might be reached which would keep a submerged vessel in suspension, but practically such a condition is next to impossible. Once a ship has started down, she will keep on until she reaches the very bottom, whether it be ten fathoms or ten hundred. A SUBMARINE GRAVEYARD Instead of the line of wandering specters, then, we must conjure up a different picture, equally weird--an under-world shrouded in darkness; for little light penetrates the deep sea. Here in the cold blackness, on the bed of the ocean, the wrecks of vessels that once sailed proudly overhead lie still and deathly silent--some keeled over on their sides, some turned turtle, and most of them probably on even keel. Here and there may be one with its nose buried deep in the mud; and in the shallower waters we may come across one pinned down by the stern, but with its head buoyed by a pocket of air, straining upward and swaying slightly with every gentle movement of the sea, as if still alive.