SWIMMING is the art of suspending and sus taining the body in water, and of making motion either forward or in any direction, by means of the arms, legs, Scc. This art, which is common to savage with civilized nations, and which must be nearly coeval with the formation of man, is under stood only by a very few of those who practice it. Though with the Greek and Romans it was not un usual to characterize the uneducated by saying, neque lileras neque natare didicit, yet swimming has very seldom been a regular branch in the education of youth."' All persons who practice this art, even those who excel in it the most, have been sell taught, and their eminence in it has been the result not of fixed rules, but of trial and perseverance.
Swimming, however, though the nature of it, and the principles on which it depends, have seldom been much attended to, is by no means a recondite or difficult art. The very contrary indeed may al most be said to be the case. The human body has been ascertained by experiment to be lighter than the same bulk of water; that is, the human body when immersed in water, displaces a quantity of that fluid heavier than itself. The body, therefore, when put in water, would necessarily float, if al lowed to remain inactive. Mr. John Robertson, (Philosophical Transactions, vol. i, p. 300 perform ed a variety of experiments on the gravity of the human body. He weighed ten different individuals, comparing their weight with the quantity of water displaced by their bodies, and the result was as fol lows:—" Excepting two, every man was lighter than his equal bulk of fresh water, and much more so than his equal bulk of salt water; consequently," he concludes, " could persons who fall into water have presence of mind enough to avoid the fright usual on such accidents, many might be preserved from drowning." Mr. Robertson, in illustration of his theory—and many similar illustrations might be given—mentions the case of a young man of thir teen, little acquainted with swimming, who, having fallen overboard from a vessel in a stormy sea, had presence of mind to turn immediately on his back, and thus remained a full half hour quietly floating on the surface of the water, when he was picked up.
Dr. Franklin's opinion on the gravity of the hu man body, when compared with water, is well known, and is most sound. He thinks that the solid parts of the human body, such as the legs, arms, head, are specifically somewhat heavier than fresh water, but lighter than salt; but that the trunk, par ticularly the upper part, from its hollowness, is so much lighter even than fresh water, that the whole of the body taken together is too light to sink wholly either in fresh or salt water. He says, that a body immersed in water would sink up to the eyes,t but "that, if the head be leaned back, so that the face looks upwards, all the back part of the face being then under water, and its weight conse quently in a great measure supported by it, the face will remain above water quite free for breathing, will rise an inch higher every inspiration, and sink as much every expiration, but never so low as that the water may cover over the mouth." He states, besides, that clothes give little additional weight in the water, though when out of it, and drenched, the case is quite otherwise. The reason why a body sinks when drowning is, that the hollow part of the trunk, &c. being filled with water, the spe cific gravity of the body is so considerably increased, that it is weightier than the quantity of water it displaces.
Under such circumstances, if the equilibrium be not destroyed, the weightier parts of the human body would sink deepest in the water, while the contrary parts would continue on the surface, or not sink far below it. Owing t., the buoyancy of the trunk, the upper part of the body is the light est; for though the head is heavy, yet not so heavy as to counterbalance the trunk. The natural posi tion, therefore, which, if the equilibrium be not in terfered with, a body would assume in water, is that erect one which it obtains on land.