CHAPTER V.
HEATING AND VENTILATION.
Of the many questions that merit attention and study in connection with the Turkish bath, all sink into insignificance by the side of that of the heating and the nature of the heat supplied in the sudatory chambers. Other things being equal, it is, after all, the heating that distinguishes one bath from another on the score of excellence. The heating of the "bath" is the Alpha and Omega of the whole matter.
There are two ways in which heat may be applied to the body—by direct radiation, as from the sun or an open fire; and by convection, as through a volume of air.
The ancient Roman bathers, with floors below them which rested upon pilæ, or little pillars of brick or tile, around which the flames and hot gases from the furnace played, and surrounded by heated, hollow walls, evidently submitted themselves to the action of a heat that must have been of a purely radiating character.
So, also, in a less perfect manner, the Turks, who employ flues running beneath the floors, and the Moors, who adopt stoves visible to the bathers.
Theoretically, radiant heat in a bath is vastly superior to that which is transmitted to the body through the medium of the air. Its virtues have been extolled by David Urquhart and other eminent authorities on the bath. "There is a difference," says Mr. Urquhart, "between radiating and transmitted caloric.... I cannot pretend to treat of this great secret of nature; to work out this problem a Liebig is required. This I can say, that such heat is more endurable than common heat. There is a liveliness about it which transmitted heat lacks. You are conscious of an electrical action. It is to transmitted heat what champagne is to flat beer.... Let us drop, if you please, the word 'bath': it is 'heat.' Let us away with that absurdity 'hot-air': it is the application of heat to the human frame." Elsewhere this writer has pointed out that the terms thermæ, sèjac, and hammâm—the names given to the bath by the Romans, Moors, and Orientals proper—mean heat, and not "hot-air" or "hot-air bath."
My own studies, observations, and experience lead me to the conclusion that the direction in which we shall improve the "Turkish bath" will be in the way of providing sudatories that shall give off pure, radiant heat in such a manner that the whole surface of the body may be sensible of a degree of heat, while the lungs may breathe comparatively cool air—air that has not passed over the sides of a fiery furnace and been suddenly raised to an enormous temperature, but which has received its heat by a gentle and gradual process of warming. Under this system the heat of which we are sensible is as the gentle Zephyr to rude Boreas or the biting eastern winds. If we go into a kiln of brickwork, such as is employed in firing clay goods, after the charge has been removed and all fumes and odours have disappeared, we shall note the soft and balmy nature of the heat that radiates directly from the walls and vaulting. We are, to all practical intents and purposes, in a Roman laconicum. The thick walls have been highly charged with caloric during the firing of the bricks or other articles. They have absorbed vast quantities of heat, and are now giving off the same to the enclosed air and to ourselves standing within. In the old Roman bath the walls were charged with caloric by means of innumerable earthen tubes lining the sides of the laconicum, and covered with a peculiar plaster. But in both cases the nature of the resultant heat is identical. It radiates to one from all sides. There is no acrid biting of the face such as one feels in the worst type of hot-air baths; no unpleasant fulness or aching of the head; and no panting or palpitating. Such is the "bath" of pure radiant heat, a thing totally distinct from, and altogether of a different genus to, the bath of heated air. And one might be pardoned for the enthusiasm which would lead one to suggest that it is only in the supplying of this kind of radiant heat in the modern bath that true and rapid progress can be expected, and possibly that not until this great or partial—according as the system of radiation and convection pertains in existing baths—revolution has been effected, will the bath, at present used by the few, become the custom of the many. Some day, peradventure, this hypothetical method of employing pure radiant heat may be rendered possible and practicable, and we may be placed in a bath where we shall receive great heat whilst breathing a comparatively cool atmosphere, and thus receive a measure of that electrical invigoration we experience when, in some sheltered bathing cove, we have exposed our bodies to the fiercest rays of the morning sun whilst yet we breathe the fresh, cool, ozone-laden air.
Till modern invention, however, has provided us with this desideratum in the heating of the bath, we must be satisfied with existing methods. And unless something really practical is perfected, it is far wiser to rely upon the system of heating by convection through the air—the principle, generally adopted, of continuously passing large quantities of freshly-heated air through the sudatory chambers; exposing, however, the heating apparatus, so that a maximum of radiant heat may be obtained; and carefully guarding against injuring the air whilst raising its temperature. If only existing baths were in perfect harmony with this principle, one would have little cause for complaint, and might the more leisurely await the perfecting of the true radiating principle of heating, which I am satisfied is the one upon which we must base all our hopes for the future of the "Turkish" bath.