HEAT, in Medicine. Great heats are not so much the immediate, as the remote, cause of a general sickness, by relaxing the fibres, and disposing the juices to putrefaction; especially among soldiers and persons exposed the whole day to the sun: for the greatest heats are seldom found to produce epidemic diseases, till the perspiration is stopped by wet clothes, fogs, dews, damps, &c. and then some bilious or putrid distemper is the certain consequence, as fluxes and ardent intermitting fevers. Nevertheless, it must be allowed, that heats have sometimes been so great as to prove the more immediate cause of particular disorders; as when
at sentinels have been placed without cover or frequent
reliefs in scorching heat; or when troops march or are
exercised in the heat of the day; or when people im-
prudently lie down and sleep in the sun. All these
circumstances are apt to bring on distempers, varying
according to the season of the year. In the begin-
ning of summer, these errors produce inflammatory fe-
vers; and in autumn, a remitting fever or dysentery.
To prevent, therefore, the effects of immoderate heats,
commanders have found it expedient so to order the
marches, that the men come to their ground before the
heat of the day; and to give strict orders, that none
of them sleep out of their tents, which, in fixed en-
campments, may be covered with boughs to shade them
from the sun. It is likewise a rule of great importance
to have the soldiers exercised before the cool of the
morning is over; for by that means not only the sultry
heats are avoided, but the blood being cooled, and the
fibres braced, the body will be better prepared to bear
the heat of the day. Lastly, in very hot weather, it
has often been found proper to shorten the sentinels
duty, when obliged to stand in the sun.