[3] In India, where out of 140 poor British prisoners shut up in a close small room 120 of them perished in one night.
Confined air, when saturated with perspirable matter,[4] will not receive more; and that matter must remain in our bodies, and occasions diseases; but it gives some previous notice of its being about to be hurtful, by producing certain uneasinesses which are difficult to describe, and few that feel know the cause. But we may recollect, that sometimes, on waking in the night, we have, if warmly covered, found it difficult to get asleep again. We turn often without finding repose in any position. This _fidgetiness_, to use a vulgar expression for the want of a better, is occasioned wholly by an uneasiness in the skin, owing to the retention of the perspirable matter, the bed-clothes having received their quantity, and, being saturated, refusing to take any more.
[4] What physicians call the perspirable matter, is that vapour which passes off from our bodies, from the lungs, and through the pores of the skin. The quantity of this is said to be five-eighths of what we eat.
When you are awakened by this uneasiness, and find you cannot easily sleep again, get out of bed, beat up and turn your pillow, shake the bed-clothes well, with at least twenty shakes, then throw the bed open, and leave it to cool; in the meanwhile, continuing undrest, walk about your chamber, till your skin has had time to discharge its load, which it will do sooner as the air may be drier and colder. When you begin to feel the cool air unpleasant, then return to your bed, and you will soon fall asleep, and your sleep will be sweet and pleasant. All the scenes presented by your fancy, will be of the pleasing kind. I am often as agreeably entertained with them, as by the scenery of an opera. If you happen to be too indolent to get out of bed, you may instead of it, lift up your bed-clothes so as to draw in a good deal of fresh air, and, by letting them fall, force it out again. This, repeated twenty times, will so clear them of the perspirable matter they have imbibed, as to permit your sleeping well for some time afterwards. But this latter method is not equal to the former.
Those who do not love trouble, and can afford to have two beds, will find great luxury in rising, when they wake in a hot bed, and going into the cool one. Such shifting of beds, would be of great service to persons ill in a fever; as it refreshes and frequently procures sleep. A very large bed, that will admit a removal so distant from the first situation as to be cool and sweet, may in a degree answer the same end.