But no part of the juices is subject to be so speedily impaired by heat as the fat or oily portion, to which it communicates a corrosive acrimony that attacks the solids themselves. Of such matters the gall is composed, and it is therefore obvious why intense heat in summer should be so liable to generate putrid gall-fevers, which are a cruel scourge of mankind. The gall, in this acrid and putrescent state, not only communicates its putridity to the nutritious juices secreted from our food, and thus infects all our humours, but also corrodes the coats of the intestines, and operates upon them at first like a violent cathartic, which causes a vomiting of gall, or a painful evacuation downward. Afterwards it eats away the coats of the intestines, so that the putrescent blood pours itself into them, and occasions a discharge of putrid blood and gall, which is called the dysentery, and terminates in mortification of the intestines and death.

Such are the fatal effects to be apprehended from intense heat; and hence summer has in all ages been considered as the parent of pestilential diseases. Historians relate, that in ancient times the heat of the dog-days had rendered the Cycladian Islands barren, and generated in them a destructive pestilence, which Aristæus was solicited to exert his skill to check. He accordingly went over to the island of Cea, had an altar erected there to Jupiter, to whom and to the Dog-star he offered sacrifice, and instituted a yearly festival in honour of the latter. Since that time arose the winds of the dog-days, which lasted forty days and tempered the heat of summer; and Diodorus Siculus seems to intimate, that after this sacrifice the pestilence ceased during the period that the winds of the dog-days blew. It is easy to imagine that cooling winds would have the effect of checking an evil which originated solely in immoderate heat.

An accidental cause why heat is generally so pernicious, are the colds which are more frequently caught in summer than in the severest winter. In cold weather we muffle ourselves up well and prevent the raw air from coming in contact with our persons. In summer, on the contrary, we are not upon our guard against them; and yet, a cool evening, a sudden shower that wets our thin summer dress, or a draught of any cold drink, may give a fatal chill. Hence arise the most dangerous inflammatory fevers,-especially pleurisy, which sweeps away so many in summer, sore throats, and, as Hippocrates observed, inflammations of the eyes, ear-ache, relaxation of the bowels, cholic, flux, and inflammatory fever, which are easily caused by obstructed transpiration.

When in hot weather the atmosphere is at the same time dry, as is more particularly the case during the prevalence of certain winds, the air extracts much the more humidity from all evaporating bodies, the less it has of its own; just in the same manner as a dry cloth which is in contact with a damp body draws the moisture to itself better than one which is wet. As then the heat affects the blood and renders it more disposed to evaporation, so the dry air promotes the latter to such a degree that the body becomes dry, and the blood loses the greater portion of its watery particles: of course the thickest and most viscous part only is left in the circulation; and in this state the blood is liable to be obstructed in the minute vessels, and this obstruction occasions inflammatory diseases, which extend the more readily to

the whole body, as the overheated blood is apt to contract putridity from the slightest cause.

The Egyptians long since learned from experience the pernicious nature of dry air, by which they frequently lost their sight. How, indeed, can it be otherwise, since the dry air draws from the eyes all that moisture which is indispensably necessary for their use? The same effect is produced on the other internal parts of the body with which the drying air comes in immediate contact. The nose and mouth are dried up by it, and the fibres of the lungs lose their elasticity, and are not so easily expanded by the air. Hence not only is respiration rendered difficult, but the heated blood is unusually expanded in the small vessels which surround the vesicles of the lungs ; so that the vacant space by which the fresh air could otherwise enter to cool it, gradually becomes more and more contracted, and almost entirely closed up by the swoollen blood-vessels. Hence many, in very intense and dry heat, are carried off by obstructions of the blood in the lungs; or, if they try to obtain relief from cold drink, by pleurisy and spasms. This is experienced by the inquisitive travellers who penetrate into the Egyptian pyramids, where the air is so hot and dry that they are obliged to strip off almost all their clothes for when they come out again they are threatened with pleurisy and death, as Norden assures us, though the climate there is very warm, if they do not immediately put on their clothes and take a small quantity of brandy, that they may afterwards quench their thirst with safety. But this is not all. The dry air paralyses also the powers of digestion and those which are subservient to the voluntary movements, because it deprives us not only of a great portion of the nutritious juices, but also of those vital spirits which are necessary for life, motion, and sensation, and without which the strongest man would be weak as a child and inanimate as a plant. Such is the state of debility, languor, and exhaustion that oppresses us in a hot and dry atmosphere. When we find ourselves in this state, it is as dangerous to seek relief from, as to remain in it. In both cases certain precautions are requisite, and these I shall now detail for the benefit of my readers.

In a dry heat the first point to which we should pay attention is, to procure in the place of our habitual abode a cool atmosphere, impregnated with pure aqueous effluvia. I am not here addressing myself to the indigent labourer, or the industrious artisan, who are obliged to sell themselves into servitude, and who neither know nor study their own convenience; I am now writing for such as have no other occupation than to watch over their health, and who can afford to station themselves for a day together at their windows, to observe the vicissitudes of wind and weather. These, if they can forego the use of carpets, may in dry heats have their floors sprinkled with water or vinegar, and various sorts of flowers, shrubs, and trees placed in water in their rooms for nothing is better adapted to impregnate the dry and hot air with a cooling moisture than plants, because they pour whole streams of water into the atmosphere.

In dry sultry weather the heat ought to be counteracted by means of a cooling diet. To this purpose cucumbers, melons, and juicy fruits are subservient. We ought to give the preference to such alimentary su bstances as tend to contract the juices which are too much expanded

by the heat, and this property is possessed by all acid food and drink. To this class belong all sorts of salad, lemons, oranges, pomegranates sliced and sprinkled with sugar, for the acid of this fruit is not so apt to derange the stomach as that of lemons; also cherries and strawberries, curds turned with lemon-acid or cream of tartar; cream of tartar dissolved in water; lemonade, and Rhenish or Moselle wine mixed with water. A lemonade composed of two bottles of Champagne, one bottle of Selter-water, three pomegranates, three lemons, and of sugar quantum sufficit, is a princely beverage in hot weather: only care must be taken that the perspiration be not thereby too much encouraged To four parts of Selter-water add one part of Moselle wine, and put a teaspoonful of powdered sugar into a wineglassful of this mixture; an ebullition takes place, and you have a sort of Champagne, which is more wholesome in hot weather than the genuine wine known by that name.

Our attention ought moreover to be directed to the means of thinning the blood, when it has been deprived by too profuse transpiration, in hot dry winds, of its aqueous particles, and rendered thick and viscid. Water would easily supply this want of fluidity, if it were capable of mingling with the blood when in this state; but as it is not strong and penetrating enough for this purpose, let a person drink ever so much of it in dry hot weather, it passes off, almost unchanged, by perspiration and urine. Acid matters have very little more effect; for the solids, totally relaxed by the loss of the vital spirits, oppose so little resistance to the fluids which circulate through thein, tha. the latter cannot by any means be intimately combined, but, on the other hand, flow almost unchanged into the open and flaccid secretory ducts of the kidneys and the skin, and must thus pass away in the form of urine and perspiration. In order, therefore, to find a menstruum by which water may be rendered capable of combining intimately with the blood, of remaining long in combination with it, and of thinning it, we must mix it with a substance possessing the property of a soap, and consequently fit to dissolve viscous matters and make them unite with water. This soap must contain but little salt, that it may not increase the thirst of the parched throat. It must not have a disagreeable taste, that we may be able to drink a considerable quantity of it; and it must be capable of recruiting the strength without overloading the stomach. Now all these qualities are to be found in yolk of egg. No beverage therefore is more suitable for hot, dry weather, than one composed of the yolk of egg beaten up with a little sugar, and mixed with a quart of water, half a glass of Rhenish wine and some lemon-juice. The wine, however, may be omitted, and lemon-juice alone used; and in like manner hartshorn-shavings boiled in water may be substituted for yolk of egg. As, in hot and dry weather, the digestive organs are in general considerably weakened, it is necessary at such times to be very temperate, especially in eating and drinking. Laertius ascribes it to the extraordinary temperance of Socrates that he alone escaped the infection of the pestilence which ravaged Attica; and let the meaning which he intends to convey in this be what it will, so much is certain, that no time is so dangerous for overloading the stomach, as when the weather has a powerful tendency to dispose our humours to putrefaction, to infect the digestive juices, and particularly the gall, and to render the organs of diges

tion, by debilitating, relaxing, drying up and consuming the animal spirits, unfit for the performance of their functions.

I have taken occasion in former papers to recommend bodily exercise in this case, however, it is not advisable. The circumstances consequent on dry heat of the atmosphere forbid us at such times to move about much. We should thereby not only increase the transpiration which is already too copious, but also weaken still more the already debilitated muscles. I hope that I shall not be charged with inconsistency, because I have in other places enjoined exercise; or I would remind my readers of a maxim of Epictetus. Every thing, says he, has two handles, by which it may be grasped-a good and a bad one. The vulgar lay hold of the latter, the philosopher of the former. Such too is the case with bodily exercise. It must be used for health, but only in such a manner as a wise man uses all things, that is to say, at proper seasons and in the proper place. The people of hot countries take a nap about noon, and walk about sunset and by moonlight. This procedure is perfectly rational and worthy of imitation. One ought, nevertheless, to seek to enjoy the fresh air, by spending the fine evenings in gardens, or at least abroad. For, as a copious transpiration takes place in a hot and dry air, and our juices at that time are disposed to putrefaction; our own effluvia become a dangerous poison, to avoid which we must quit and ventilate the apartments where they have accumulated, and seek the fresh air in order to escape malignant pestilential fevers. Rhasis mentions a pestilence which did not attack any hunters, because they were so much in the open air, and lived regularly. But if the "noble sport" is prohibited in this country in summer, we can at least take the air and exercise in the cool of the day, and these with temperance and sobriety will preserve us from many dangers.

In hot and dry weather sleep is requisite for recruiting the wasted spirits and powers; but it is attended with this inconvenience, that the heating of the bed, against which we cannot guard, either accelerates the circulation of the blood and produces a dry heat which prevents sleep, or renders it dangerous, restless, and unrefreshing by profuse perspiration. To obviate the agitation of the blood and the dry heat which prevents sleep, it would be advisable to take at bed-time one of the drinks which I have recommended above for hot weather, or some kind of cooling and sedative medicine. To avoid too profuse perspiration, it is necessary to sleep in cool chambers, where a window may be thrown up, and before it should be placed a gauze blind, to allow free access to the fresh air, without admitting insects. The bed should not be too soft, otherwise it is apt to overheat one; and on this account mattresses are preferable to featherbeds. But the best method would be to sleep in hammocks; and indeed I cannot conceive why this practice should not be as common on shore in summer as it is on shipboard all seasons of the year.

As to apparel it should be observed, that in dry heat we ought not to dress too lightly, and still less to uncover any part entirely. The effects of dry heat and of cold on our bodies are not so very different as might be imagined. This may be seen in the brute animals. It is owing merely to the cold that they change their coat towards winter; and it is to be ascribed solely to the heat if they do the same at the approach of summer. For, whence should it otherwise proceed, that

our cats and dogs, which in our houses are not exposed to the vicissitudes of heat and cold, do not change their hair like the wild animals; but in the countries about Hudson's Bay, change it, according to Ellis, exactly like the wild animals, as soon as the weather becomes warm? The same voyager confirms the assertion, that a great degree of cold produces the same effects on the human body as a great degree of heat, and assures us that he has cured frost-bitten limbs with the very same applications as would have proved efficacious if they had been burned. Buffon observes, "When the cold is very intense, it produces effects similar to those of intense heat. The skin of the Samoyedes, Laplanders, and Greenlanders is of a dark-brown colour; nay, some of the latter are said to be as black as negroes. Cold must therefore, like heat, dry and alter the skin, and impart to it a dark colour." Thus too we find in Pontoppidan the following remark: "The Laplanders are shorter than the Norwegians and Swedes; they have flatter faces, invariably a dark-brown colour and black hair. This fact demonstrates that where the temperate climate ceases and intense cold prevails, the latter does not make men white, but like intense heat itself communicates to them a very dark colour." Without pursuing this digression farther, I will proceed to apply these observations. If great heat and great cold produce similar effects on our bodies, it seems reasonable that we should not adopt a totally different mode of proceeding in both. It is a precept of Nature to defend the body by clothing from the influence of cold, for Nature herself follows this principle in regard to the brutes: If then heat produces the very same effects on us as cold, it seems reasonable that we should protect ourselves against them also. Clothes are by no means intolerable in heat, and he must be very impatient who would strip them off. They defend us against the heat of the sun, and to this purpose garments made of woollen cloth, of light colours, are much better adapted than thinner stuffs. They prevent the catching of cold so easily in consequence of a shower or a high wind. They are not so soon impregnated with perspiration, which facilitates the taking of cold and as they are somewhat warmer than silks or thin stuffs, they are better suited to keep up the transpiration, and thereby to prevent the dry heat which arises from the agitation of the blood on account of obstruction of the pores, and which is always more intolerable than to perspire a little. We derive this additional advantage from wearing in all seasons the same sort of clothes, which are neither too cold nor too hot, that we accustom our feelings much more easily to all kinds of weather, and prevent a thousand dangers, arising solely from the incautious change of dress and its inevitable consequences.

As it is time to bring this paper to a close, I shall conclude it with a few general warnings, When heated, and in a state of perspiration, beware of courting the refreshing coolness of a current of air, or of damp grottoes through which water runs, and likewise of throwing off your clothes. Use no drink cooled with ice, but only beverage of a moderate temperature. Change your linen, when wet with perspiration and while yet warm; and take no more brandy or other spirituous liquors than is necessary to excite the salivary glands a little, to moisten the mouth, and to impart some strength to the exhausted nerves. For this purpose a small quantity held in the mouth will in general prove sufficient.