is easy to see that it is not dragging through the water, but over the ground. "I often went to the bow," says Mr. Field, "and sat on the rope, and could tell by the quiver that the grapnel was dragging on the bottom two miles under us." And thus, with its fishing line set, the great ship moves slowly down over where the cable lies. As the grapnel drags on the bottom, one of the engineer's staff stands at the dynamometer to watch for the moment of increasing strain. A few hours pass, and the index rises to eight, ten, or twelve tons, sure token that there is something at the end of the line--it may be the lost cable, or a sunken mast or spar, the fragment of a wreck that went down in a storm that swept the Atlantic a hundred years ago. And now the engine is set in motion to haul in. As the rope comes up, it passes over a five-foot drum, every revolution bringing up three fathoms. Thus it takes some hours to haul in over two miles' length, perhaps at last to find nothing at the end! Success in hooking the cable depends on the accuracy of their observations. These were sometimes verified in a remarkable manner. When the nights were very dark and thick with fog, so that they could not see the stars above nor their lights on the ocean, they had to go almost by the sense of feeling. Yet so exactly had they taken their bearings, that they could almost grope over the ground with their hands. A singular proof of this was given one night, when, just as the line began to quiver, showing that the cable had been hooked, one of the buoys--which had not been seen in the darkness--thumped against the side of the ship. So exactly had it been placed over the prescribed line, that the ship struck the buoy just as the grapnel struck the cable! The accident, which startled them at first, when it occurred in the gloom of night, furnished the strongest proof of the accuracy of their observations; and the officers were very proud of it, as they well might be, as a victory in nautical astronomy! These different experiments revealed some secrets of the ocean. Its bottom proved to be generally ooze, a soft slime. When the rope went down, one or two hundred fathoms at the end would trail on the sea floor; and when it came up, this was found coated with mud, "very fine and soft like putty, and full of minute shells." But it was not _all_ ooze at the bottom of the sea, even on this telegraphic plateau. There were hidden rocks--perhaps not cliffs and ledges, but at least scattered boulders, lying on that mighty plain. Sometimes the strain on the dynamometer would suddenly go up three or four tons, and then back again, as if the grapnel had been caught and broken away. Once it came up with two of its hooks bent, as if it had come in contact with a huge rock. At one time it brought up in the mud a small stone half the size of an almond; and at another a fragment as large as a brick. This was a piece of granite.