1869.] On Warming and Ventilation. 723 thus not only supplying warm air, to the apartment, but, also to the flue. These fireplaces, seldom, if ever smoked, and the occupants of the room, were not troubled with cold backs. Radiant heat has peculiar properties ; one, highly important to health, is, that it passes through the atmosphere without warming it. The atmosphere receives its warmth, from contact with bodies warmer than itself, and not from radiant heat. The rays of the sun, impinging upon solid and liquid bodies, warms them (but not the air) and they give up some of their heat, to the atmosphere in contact with them. Thus, rendering the heated air lighter, it passes up in currents, and is wafted and mixed through and around, with the cooler strata of air having but a moderate temperature. Thus in a room, having in it a open fire, the rays from which passing through the intermediate air, impinge upon our persons, and thus we are warmed, — but not by hot air. In a room heated by a furnace, by hot air, we haA r e but little if any radiant heat. In this last case we inhale hot air into our lungs ; in the first case we inhale cold air. Look at the difference, let any one taste hot water of 140° F, or let him in- hale hot water of that temperature; try it with a thermometer ; and he will suffer a painful ordeal. Yet we, in the hot weather of summer, go out into the rays of the sun with the thermometer at 140 F°, without noticiug any extra heat in our windpipe or lungs; and whj^ ? because, though the thermometer is heated to 140°, the atmosphere is not above 90° or 95° F ; and we inhale a comparatively cool air. This property of radiant heat, is a wise provision for our welfare ; but we civilized beings, in this, as in many other of our ways, go in direct violation of nature's laws, and then wonder why our constitutions are broken up. Ani- mal heat, is for the most part, generated in the lungs, by the act of respiration ; the interior of the body, is therefore much warmer than the exterior; and that condition, is its natural equilibrium, and is absolutely essential to the health}^ action of the functions of life. Thus, the air not receiving heat directly from radiant heat, is cool on entering the lungs, thus absorbing the heat therein generated, and preventing an abnormal degree of heat in the lungs ; not above 98° F ; the exterior surface of the body, however, is receiving radiant heat of the temperature of 140* F. I have placed myself in front of an open fire, with athermometer by my face indi- cating a temperature of 120° F ; and j'et my organs of respiration were free from oppression and insensible to an extra de- gree of heat. In truth the air entering my lungs was perhaps not above 60° F; Let any one raise the temperature of a hot air apartment to 120* F ; and it will be intolerable. The lungs could not long endure it. A man may enter a red hot furnace, if the ventilation of air is free, without suffering in respiration. Heated air too, being expanded, and of greater volume than natural air, affords in respiration less oxygen to the lungs than cool air ; hence the dul- ness of spirits of one occupying a room thus heated ; and the scarcity of ox3'gen in the lungs affords a less quantity of heat in the lungs for the supply of the body, thus causing a sensation of chilli- ness in one occupying a hot air room. I have written this long article, because I am sure, that no one can im- prove on the modes of heating, and ven- tilation, unless with a knowledge of physics, but that with this knowledge, there will be a return to the old-fashioned methods of heating (improved, doubt- less,) by radiant heat. The rays of heat reach in their effects a long, long distance. A Countryman. April 5th, 1869.
