"In all these submarine mines," says Mr. Henwood, "I have heard the dashing of the billows and the grating of the shingle when in calm weather. I was once, however, underground in Wheal Cock during a storm. At the extremity of the level seaward some eighty or one hundred fathoms from the shore, little could be heard of its effects, except at intervals, when the reflux of some unusually large wave projected a pebble outward, bounding and rolling over the rocky bottom. But when standing beneath the base of the cliff, and in that part of the mine where but nine feet of rock stood between us and the ocean, the heavy roll of the large boulders, the ceaseless grinding of the pebbles, the fierce thundering of the billows, with the crackling and boiling as they rebounded, placed a tempest in its most appalling form too vividly before me ever to be forgotten. More than once doubting the protection of our rocky shield, we retreated in affright, and it was only after repeated trials that we had confidence to pursue our investigations." Yet the miners, accustomed from their early youth to the fierce and threatening roaring of the stormy sea, pursue their work from year to year, never doubting that the thin roof which separates them from a watery grave will continue to protect them, as it has shielded their fathers before them. PART II. THE INHABITANTS OF THE SEA. CHAP. VIII. THE CETACEANS. General Remarks on the Organisation of the Cetaceans.--The Large Greenland Whale.--His Food and Enemies.--The Fin-Back or Rorqual.--The Antarctic Whale.--The Sperm-Whale.--The Unicorn Fish.--The Dolphin.--Truth and Fable.--The Porpoise.--The Grampus.--History of the Whale Fishery. Of all the living creatures that people the immensity of ocean, the cetaceans, or the whale family, are the most perfect. Their anatomical construction renders them in many respects similar to man, and their heart is susceptible of a warmth of feeling unknown to the cold-blooded fishes; for the mother shows signs of attachment to her young, and forgets her own safety when some danger menaces her offspring. Like man, the cetaceans breathe through lungs, and possess a double heart, receiving and propelling streams of _warm_ red blood. The anatomical structure of their pectoral fins bears great resemblance to that of the human arm, as the bony structure of those organs equally consists of a shoulder-blade, an upper arm, a radius and ulna, and five fingers.