art or act of sustaining the body in water, and of moving therein; in which action the air-bladder and fins of fishes bear a considerable part.

Though a great deal depends on the motion of the muscles of the several parts of the body, in the swimming of the fish; yet the tail, and those muscles which move the lower part of the body to which it is affixed, are the great instruments by which their swift motions in the water are performed. The moving the tail, and that part of the body to which it adheres, backward and forward, or sideways any one way, throws the whole body of the fish strongly the contrary way; and even in swimming straight forward, the motion and direction are both greatly assisted by the vibrations of this part, as may be experienced in the motion of a boat, which, when impelled forward, may be firmly guided by means of an ear held out at its stern, and moved in the water as occasion directs. The dorsal muscles, and those of the lower part of the body between the anus and tail, are the principal that are used in the motion of this part, and these are therefore the most useful to the fish in swimming. The muscles of the belly seem to have their principal use in contracting the belly and the air-bladder. They have been supposed of use to move the belly-fins; but there are too many of them for such a purpose, and these fins have each its peculiar muscle fully sufficient to the business.

The use of the tail in swimming is easily seen, by cutting it off, and committing the fish to the water without it, in which case it is a most helpless creature.

By the help of the tail they also turn about, by striking strongly with it on one side, and keeping it bent, so as to act like the rudder of a ship. The fins, especially the pectoral ones, serve to keep the fish upright, as also to ascend and descend.

Brutes swim naturally; but men attain this art by practice and industry. It consists principally in striking alternately with the hands and feet; which, like oars, row a person forward: he must keep his body a little oblique, that he may the more easily erect his head, and keep his mouth above water.

Swine, in zoology. See Sus.

Swingling, the beating of flax or hemp. See Flax.