Frequently the trap rock is honeycombed in a curious fashion,--filled with small holes on the surface, as if drops of water falling for years in the same spots had worn these smooth round hollows. This always happens close to the water, and only in the trap rock, and looks as if it might be the result of the flying spray which, in winter and toward spring, when the northwest gales blow sometimes for three weeks steadily day and night, beats continually upon the shore. [Illustration: TRAP DIKE, APPLEDORE.] The coast-line varies, of course, with high or low tide. At low water the shores are much more forbidding than at high tide, for a broad band of dark sea-weed girdles each island, and gives a sullen aspect to the whole group. But in calm days, when the moon is full and the tides are so low that it sometimes seems as if the sea were being drained away on purpose to show to eager eyes what lies beneath the lowest ebb, banks of golden green and brown moss thickly clustered on the moist ledges are exposed, and the water is cut by the ruffled edges of the kelps that grow in brown and shining forests on every side. At sunrise or sunset the effect of the long rays slanting across these masses of rich color is very beautiful. But at high tide the shores are most charming; every little cove and inlet is filled with the music of the waves, and their life, light, color, and sparkle. Who shall describe that wonderful noise of the sea among the rocks, to me the most suggestive of all the sounds in nature? Each island, every isolated rock, has its own peculiar rote, and ears made delicate by listening, in great and frequent peril, can distinguish the bearings of each in a dense fog. The threatening speech of Duck Island’s ledges, the swing of the wave over Halfway Rock, the touch of the ripples on the beach at Londoner’s, the long and lazy breaker that is forever rolling below the lighthouse at White Island,--all are familiar and distinct, and indicate to the islander his whereabouts almost as clearly as if the sun shone brightly and no shrouding mist were striving to mock and to mislead him.