perience every variety of diftrefs. Obferve, however, that the quantities of food and exercife are relative things: those who move much may, and indeed ought, to eat more; thofe who use little exercise, should eat little. In general, mankind, fince the improvement of cookery, eat about twice as much as nature requires. Suppers are not bad, if we have not dined; but reftless nights naturally follow hearty fuppers, after full dinners. Indeed, as there is a difference in constitutions, fome reft well after thefe meals; it costs them only a frightful dream, and an apoplexy, after which they fleep till doomsday. Nothing is more common in the newspapers, than inftances of people, who, after eating a hearty fupper, are found dead a-bed in the morning. Another means of preferving health, to be attended to, is the having a conftant fupply of fresh air in your bed chamber. chamber. It has been a great mistake, the fleeping in rooms exactly closed, and in beds furrounded by curtains. No outward air, that may come into you, is fo unwholfome as the unchanged air, often breathed, of a clofe chamber. As boiling water does not grow hotter by longer boiling, if the particles that receive greater heat can escape; fo living bodies do not putrify, if the particles, as faft as they become putrid, can be thrown off. Nature expels them by the pores of the fkin and lungs, and in a free open air, they are carried off; but, in a close room, we receive them again and again, though they become more and more corrupt. A number of perfons crowded into a small room, thus fpoil the air in a few minutes, and even render it mortal, as in the Black Hole at Calcutta. A fingle perfon is faid to fpoil only a gallon of air per minute, and therefore requires a longer time to fpoil a chamber full; full; but it is done, however, in proportion,and many putrid disorders hence have their origin. It is recorded of Methusalem, who, being the longest liver, may be supposed to have best preserved his health, that he slept always in the open air; for, when he had lived five hundred years, an angel faid to him: "Arife, "Methufalem; and build thee an house, "for thou shalt live yet five hundred years longer." But Methufalem anfwered and faid: "If I am to live but "five hundred years longer, it is not "worth while to build me an house-I "will sleep in the air as I have been used "to do." Phyficians, after having for ages contended that the fick fhould not be indulged with fresh air, have at length. difcovered that it may do them good. It is therefore to be hoped that they may in time difcover likewise, that it is not hurtful to those who are in health; and that we may be then cured of the aërophobia aerophobia that at prefent diftreffes weak minds, and make them choose to be ftifled and poisoned, rather than leave open the window of a bed-chamber, or put down the glafs of a coach. Confined air, when faturated with pers spirable matter *, will not receive more! and that matter muft remain in our bo dies, and occafion diseases: but it gives fome previous notice of its being about to be hurtful, by producing certain uneafineffes, flight indeed at first, fuch as, with regard to the lungs, is a trifling fenfation, and to the pores of the skin a kind of reftleffness which is difficult to defcribe, and few that feel it know the cause of it. But we may recollect, that fometimes, on waking in the night, we have, if warmly covered, found it * What phyficians call the perspirable matter, is that vapour which paffes off from our bodies, from the lungs, and through the pores of the skin. The quantity of this is faid to be five-eighths of what we eat. difficult 1 difficult to get asleep again. We turn often without finding repofe in any po fition. This figgettinefs, to use a vulgar expreffion for want of a better, is occafioned wholly by an uneafiness in the skin, owing to the retenfion of the perfpirable matter-the bed-clothes having received their quantity, and, being faturated, refufing to take any more. To become fenfible of this by an experiment, let a person keep his position in the bed, but throw off the bed-clothes, and fuffer fresh air to approach the part uncovered of his body; he will then feel that part fuddenly refreshed; for the air will immediately relieve the skin, oy receiving, licking up, and carrying off, the load of perfpirable matter that incommoded it. For every portion of cool air that approaches the warm fkin, in receiving its part of that vapour, receives therewith a degree of VOL. I. heat, E |