Almost any one, falling into a river, will be enabled to float, if he suffer the specific gravity of the water fairly to be adduced in comparison with his own - that is to say, if he suffer his whole person to be immersed, with as little exception as possible. The proper position for one who cannot swim, is the upright position of the walker on land, with the head thrown fully back, and immersed; the mouth and nostrils alone remaining above the surface. Thus circumstanced, we shall find that we float without difficulty and without exertion. It is evident, however, that the gravities of the body, and of the bulk of water displaced, are very nicely balanced, and that a trifle will cause either to preponderate. An arm, for instance, uplifted from the water, and thus deprived of its support, is an additional weight sufficient to immerse the whole head, while the accidental aid of the smallest piece of timber will enable us to elevate the head so as to look about. Now, in the struggles of one unused to swimming, the arms are invariably thrown upwards, while an attempt is made to keep the head in its usual perpendicular position. The result is the immersion of the mouth and nostrils, and the inception, during efforts to breathe while beneath the surface, of water into the lungs. Much is also received into the stomach, and the whole body becomes heavier by the difference between the weight of the air originally distending these cavities, and that of the fluid which now fills them. This difference is sufficient to cause the body to sink, as a general rule; but is insufficient in the cases of individuals with small bones and an abnormal quantity of flaccid or fatty matter. Such individuals float even after drowning.
"The corpse, being. supposed at the bottom of the river, will there remain until, by some means, its specific gravity again becomes less than that of the bulk of water which it displaces. This effect is brought about by decomposition, or otherwise. The result of decomposition is the generation of gas, distending the cellular tissues and all the cavities, and giving the puffedappearance which is to horrible. When this distension has so far progressed that the bulk of the corpse is materially increased with. out a corresponding increase of mass or weight, its specific gravity becomes less than that of the water displaced, and it forthwith makes its appearance at the surface. But decomposition is modified by innumerable circumstances - is hastened or retarded by innumerable agencies; for example, by the heat or cold of the season, by the mineral impregnation or purity of the water, by its depth or shallowness, by its currency or stagnation, by the temperament of the body, by its infection or freedom from disease before death. Thus it is evident that we can assign no period, with any thing like accuracy, at which the corpse shall rise through decomposition. Under certain conditions this result would be brought about within an hour; under others, it might not take place at all. There are chemical infusions by which the animal frame can be preserved foreverfrom corruption; the Bi-chloride of Mercury is one. But, apart from decomposition, there may be, and very usually is, a generation of gas within the stomach, from the acetous fermentation of vegetable matter (or within other cavities from other causes) sufficient to induce a distension which will bring the body to the surface. The effect produced by the firing of a cannon is that of simple vibration. This may either loosen the corpse from the soft mud or ooze in which it is imbedded, thus permitting it to rise when other agencies have already prepared it for so doing; or it may overcome the tenacity of some putrescent portions of the cellular tissue; allowing the cavities to distend under the influence of the gas.
"Having thus before us the whole philosophy of this subject, we can easily test by it the assertions of L'Etoile. 'All experience shows,' says this paper, 'that drowned bodies, or bodies thrown into the water immediately after death by violence, require from six to ten days for sufficient decomposition to take place to bring them to the top of the water. Even when a cannon is fired over a corpse, and it rises before at least five or six days' immersion, it sinks again if let alone.'
"The whole of this paragraph must now appear a tissue of inconsequence and incoherence. All experience does not show that 'drowned bodies' require from six to ten days for sufficient decomposition to take place to bring them to the surface. Both science and experience show that the period of their rising is, and necessarily must be, indeterminate. If, moreover, a body has risen to the surface through firing of cannon, it will not 'sink again if let alone,' until decomposition has so far progressed as to permit the escape of the generated gas. But I wish to call your attention to the distinction which is made between 'drowned bodies,' and 'bodies thrown into the water immediately after death by violence.' Although the writer admits the distinction, he yet includes them all in the same category.