At the depth of twenty feet he touched the tops of the sea-kelp growing on the rocks below,—he could feel the long tongues of leaves scraping his legs. Then, as he sank deeper, his shoes struck an outlying boulder. Caleb pushed himself off, floated around it, measured it with his arms, and settled to the gravel. He was now between the outlying boulder and the Ledge. Here he raised himself erect on his feet and looked about: the gravel beneath him was white and spangled with starfish; little crabs lay motionless, or scuttled away at his crunching tread; the sides of the isolated boulder were smooth and clean, the top being covered with waving kelp. In the dim, greenish light this boulder looked like a weird head,—a kind of submarine Medusa, with her hair streaming upward. The jagged rock-pile next it, its top also covered with kelp, resembled a hill of purple and brown corn swaying in the ceaseless current. Caleb thrust his hand into his haversack, grasped his long knife, slashed at the kelp of the rock-pile to see the bottom stones the clearer, and sent a quick signal of “All right—lower away!” through the life-line, to Lacey, who stood on the sloop’s deck above him. Almost instantly a huge square green shadow edged with a brilliant iridescent light sank down towards him, growing larger and larger in its descent. Caleb peered upward through his face-plate, followed the course of the stone, and jerked a second signal to Lacey’s wrist. This signal was repeated in words by Lacey to Captain Brandt, who held the throttle, and the shadowy stone was stopped within three feet of the gravel bottom. Here it swayed slowly, half turned, and touched on the boulder. Caleb watched the stone carefully until it was perfectly still, crept along, swimming with one hand, and measured carefully with his eye the distance between the boulder and the Ledge. Then he sent a quick signal of “Lower—all gone,” up to Lacey’s wrist. The great stone dropped a chain’s link; slid halfway the boulder, scraping the kelp in its course; careened, and hung over the gravel with one end tilted on a point of the rocky ledge. As it hung suspended, its lower end buried itself in the gravel near the boulder, while the upper lay aslant up the slope of the rock-covered ledge.