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other respects the means of procuring a progressive motion. When he is seized with the cramp in the leg, the method of driving it away is to give to the parts affected a sudden, vigorous and violent shock; which he may do in the air, as he swims, on his back.
During the great heats of summer, there is no danger in bathing, however warm we may be, in rivers which have been thoroughly warmed by the sun, But to throw one's self into cold spring water, when the body has been heated by exercise in the sun, is an imprudence which may prove fatal. I once knew an instance of four young men, who, having worked at harvest in the heat of the day, with a view of refreshing themselves, plunged into a spring of cold water: two died upon the spot, a third the next morning, and the fourth recovered with great difficulty. A copious draught of cold water, in similar circumstances, is frequently attended with the same effect in North America.
The exercise of swimming is one of the most healthy and agreeable in the world. After having swam for an hour or two in the evening, one sleeps coolly the whole night, even during the most ardent heat of summer. Perhaps the pores being cleansed, the insensible perspiration increases, and accasions this coolness. It is certain, that much swimming is the means of stopping a diarrhoea, and even of producing a constipation. With respect to those who do not know how to swim, or who are affected with a diarrhoea at a season which does not permit them to use that exercise, a warm bath, by cleansing and purifying the skin, is found very salutary, and often effects a radical cure. I speak from my own experience, frequently repeated, and that of others, to whom I have recommended this.
As the ordinary method of swimming is reduced to the act of rowing with the arms and legs, and is consequently a laborious and fatiguing operation when the space of water to be crossed is considerable; there is a method in which a swimmer may pass to great distances with much facility, by means of a sail. This discovery I fortunately made by accident and in the following manner :
When I was a boy, I amused myself one day with flying a paper kite; and approaching the bank of a pond, which was near a mile broad, I tied the string to a stake, and the kite ascended to a very considerable height above the pond, while I was swimming. In a little time, being desirous of amusing myself with my kite, and enjoying at the same time the pleasure of swimming, I returned, and loosing from the stake the string with the little stick which was fastened to it, went again into the water, where I found that, lying on my back, and holding the stick in my hands, I was drawn along the surface of the water in a very agreeable manner. Having engaged another boy to carry my clothes round the pond, to a place which I pointed out to him, on the other side,
began to cross the pond with my kite, which carried me quite over without the least fatigue, and with the greatest pleasure imaginable. I was only obliged occasionally to halt a little in my course, and resist its progress when it appeared that, by following too quick, I lowered the kite too much; by doing which occasionally I made it rise again. I have never since that time practised this singular mode of swimming, though I think it not impossible to cross in this manner from Dover to Calais. The packet-boat, however, is still preferable.
NEW MODE OF BATHING.
EXTRACTS OF LETTERS TO M. DUBOURG. London, July 28th, 1768. I GREATLY approve the epithet which you give, in your letter of the 8th of June, to the new method of treating the small-pox, which you call the tonic or bracing method; I will take occasion, from it, to mention a practice to which I have accustomed myself. You know the cold bath has long been in Vogue here a tonic; but the shock of the cold water hath always appeared to me, generally speaking, as too violent, and I have found it much more agreeable to my constitution to bathe in another element -I mean cold air. With this view I rise early almost every morning, and sit in my chamber, without any clothes whatever, half an hour or an hour, according to the season, either reading or writing. This practice is not in the least painful, but on the contrary, agreeable: and if I return to bed afterward, before I dress myself, as it sometimes happens, I make a supplement to my night's rest of one or two hours of the most pleasing sleep that can be imagined. I find no ill consequences whatever resulting from it, and that at least it does not injure my health, if it does not in fact contribute to its preservation. I shall therefore call it for the future a bracing or tonic bath.
March 10th, 1773.
I shall not attempt to explain why damp clothes occasion cold, rather than wet ones, because I doubt the fact; I imagine that neither the one nor the other contribute to this effect, and that the causes of colds are totally independent of wet, and even of cold. I purpose writing a short paper on this subject, the
first moment of leisure I have at my disposal.—In the meantime, I can only say, that having some suspicions that the common notion, which attributes to cold the property of stopping the pores and obstructing the perspiration, was ill-founded, I engaged a young physician, who is making some experiments with Sanctorius's balance, to estimate the different proportions of his perspirations when remaining one hour quite naked, and another warmly clothed. He pursued the experiment in this alternate manner for eight hours successively, and found his perspiration almost double during those hours in which he was naked.
OBSERVATIONS ON THE GENERALLY PREVAILING
To the same.
YOUR observations on the causes of death, and the experiments which you propose for recalling to life those who appear to be killed by lightning; demonstrate equally your sagacity and humanity. It appears that the doctrines of life and death, in general, are yet but little understood.
A toad buried in the sand will live, it is said, until the sand becomes petrified; and then, being inclosed in the stone, it may live for we know not how many ages. The facts which are cited in support of this opinion, are too numerous and too circumstantial not to deserve a certain degree of credit. As we are accustomed to see all the animals with which we are acquainted eat and drink, it appears to us difficult to conceive how a toad can be supported in such a dungeon. But if we reflect that the necessity of nourishment which animals experience in their ordinary state,
proceeds from the continual waste of their substance by perspiration: it will appear less incredible, that some animals, in a torpid state, perspiring less because they use no exercise, should have less need of aliment; and that others, which are covered with scales or shells, which stop perspiration, such as land and sea turtles, serpents, and some species of fish, should be able to subsist a considerable time without any nourishment whatever. A plant with its flowers, fades and dies immediately, if exposed to the air without having its roots immersed in a humid soil, from which it may draw a sufficient quantity of moisture to supply that which exhales from its substance, and is carried off continually by the air. Perhaps, however, if it were buried in quicksilver it might preserve for a considerable space of time, its vegetable life, its smell, and colour. If this be the case it might prove a commodious method of transporting from distant countries those delicate plants which are unable to sustain the inclemency of the weather at sea, and which require particular care and attention.
I have seen an instance of common flies preserved in a manner somewhat similar. They had been drowned in Madeira wine, apparently about the time it was bottled in Virginia, to be sent to London. At the opening of one of the bottles at the house of a friend where I was, three drowned flies fell into the first glass that was filled. Having heard it remarked that drowned flies were capable of being revived by the rays of the sun, I proposed making the experiment upon these. They were therefore exposed to the sun, upoh a sieve which had been employed to strain them out of the wine. In less than three hours, two of them by degrees began to recover life. They commenced by some convulsive motions in the