. Animal physiology. Physiology, Comparative; Physiology, Comparative. PROPULSION IN WATER BY EXPANDED TATL. 491. Fig. 229.—Tail-Fin of Whale. very powerful muscles that are attached to the spine, and give to this organ an enormous force and great variety of motion. The texture of the portion of it by which the blow is usually given, is such that it can hardly be injured; it is so tough that it cannot be torn, and so free from feeling, that a stroke of it against a hard substance gives no pain to the animal. If it strikes a boat across the middle with the edge, the boat is cut asunder as clean
. Animal physiology. Physiology, Comparative; Physiology, Comparative. PROPULSION IN WATER BY EXPANDED TATL. 491. Fig. 229.—Tail-Fin of Whale. very powerful muscles that are attached to the spine, and give to this organ an enormous force and great variety of motion. The texture of the portion of it by which the blow is usually given, is such that it can hardly be injured; it is so tough that it cannot be torn, and so free from feeling, that a stroke of it against a hard substance gives no pain to the animal. If it strikes a boat across the middle with the edge, the boat is cut asunder as clean and suddenly as if by one stroke of a giant axe ; whereas, if it strikes with the flat surface, the boat is driven to the depth of many fathoms with the swiftness of an arrow. Hence this tail is a most efficient instrument for the propulsion of the bulky body of the Whale through the water; and it is, in fact, its principal organ of locomotion. The paddles formed by the fore-feet are placed near the centre of gravity of the wThole mass ; and thus can readily exert their peculiar action, which is that of changing the direction of the movement, and especially of raising and lowering the body. 666. The propulsion of the body by the stroke of the tail in Whales and Fishes, is effected precisely in the same manner as the urging forwards a boat through the water, when accom- plished by the motion of an oar at the stern from side to side,— in the mode commonly termed sculling. The expansion of the Whale's tail-fin being horizontal, its stroke is vertical, and may thus readily bring the animal to the surface of the water for occasional respiration, as well as propel it forwards; but that of the Fishes body and tail being vertical, its stroke is horizontal, and its action will simply be, to urge the body through the water. The power of ascending and descending, as well as of. Please note that these images are extracted from scanned page images that may have been digitally enhanced
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Keywords: ., bookauthorcarpenterwilliambenja, bookcentury1800, bookdecade1840
