I clambered among the huge blocks of granite that nothing less than steam could now have stirred, although they had once been displaced by a few drops of water acting together. A terrible rent in the east side of the cliff is locally known as the Spouting Horn. Down at its base the sea has worn through the rock, leaving a low arch. At the flood, with sufficient sea on, and an off-shore wind, a wave rolls in through the cavity, mounts the escarpment, and leaps high above the opening with a roar like the booming of heavy ordnance. These natural curiosities are not unfrequent along the coast. There is one of considerable power at Cape Arundel, Maine, that I have heard when two miles from the spot. Unfortunately for the tourist, these grand displays are usually in storms, when few care to be abroad; undoubtedly, the outward man may be protected and the inward exalted at such times. Some of the more adventurous go through the Horn: I went around it. I saw here a few ruminant sheep gazing off upon the sea. What should a sheep see in the ocean? On the farther side of the cove is a sea-cavern that has the reputation of being the finest on the island. Within its gloomy recesses are rock pools of rare interest to the naturalist. In proper season they will be found inhabited by the sea-anemone and other and more debatable forms of animal life. Some of these aquaria I have seen are of marvelous beauty, recalling the lines, "Full many a gem of purest ray serene The dark unfathomed caves of ocean bear." Lined with mother-of-pearl and scarlet mussels, resting on beds of soft sponge or purple moss-tufts, these fairy grottoes are the favorite retreat of King Crab and his myrmidons, of the star-fish and sea-urchin. Twice in every twenty-four hours the basins are refilled with pure sea-water, than which nothing can be more transparent. Strange that these rugged crags, where the grasp of man would be loosened by the first wave, should be instinct with life! It required some force to detach a mussel from its bed, and you must have recourse to your knife to remove the barnacles with which the smoother rocks are incrusted. John Adams, when he first saw the sea-anemone, compared it, in figure and feeling, to a young girl's breast. [Illustration: DEVIL'S DEN AND SCHOONER HEAD.] Mount Desert has been familiar to two of the greatest of American naturalists. When Audubon was preparing his magnificent "Birds of America," he visited the island, and I have no doubt the report of his rifle was often heard echoing among the mountains or along the shores. Agassiz was also here, interrogating the rocks, rapping their stony knuckles with his hammer, or pressing their gaunt ribs with playful familiarity. Audubon died in 1851. Agassiz is more freshly remembered by the present generation, to whom he made the pathway of Natural Science bright by his genius, and pleasant, by his genuine, whole-hearted _bonhomie_.