WARMING-VENTILATION-LIGHTING. 



WARMING. 



HP H E average temperature of the human body 

 J. is from 98 to 100; and whether the indi- 

 vidual be exposed to a tropical or to an arctic cli- 

 mate, his blood never rises above or falls below the 

 medium more than one or two degrees, whatever 

 his feelings of heat or cold may be. It seems as if 

 this amount of heat, and no other, were consistent 

 with the existence of warm-blooded animals ; for if 

 by any means the temperature of an animal's body 

 is reduced below the above limit, its vital action 

 declines, and soon comes to a stand. In like 

 manner, when heated seven or eight degrees 

 above its usual warmth, the vitality is destroyed. 



The temperature thus necessary for the life of 

 the body, is maintained by the action of that life 

 itself. Objects surrounding the body being in 

 almost all cases colder than it, are constantly 

 stealing part of its warmth ; but within the system 

 there is an incessant process of combustion going 

 on, producing fresh heat, exactly as the fire in a 

 grate does. When the heat thus generated is not 

 dissipated fast enough, so that the body tends to 

 become warmer than the due degree, the accumu- 

 lation finds vent in perspiration, the evaporation 

 of which carries off the excess (see NATURAL 

 PHILOSOPHY). In general, however, the tendency 

 is the other way ; the heat of the body, if allowed 

 freely to escape, would be dissipated faster than it 

 is produced; and hence arises the necessity of 

 clothing, houses, and other means of retarding its 

 escape. The lower animals are in general pro- 

 vided by nature with coverings for this purpose, 

 according to the requirements of the climate in 

 which they live. Man is left to the exercise of his 

 inventive faculties to provide clothing and shelter 

 for himself. In the lower animals, too, the heat- 

 producing function is more active than in man. 

 At least, this is true of civilised man ; for there can 

 be no doubt that the naked and painted savages 

 that inhabited these islands 2000 years ago had 

 a power of resisting cold unknown to us their 

 descendants. Even in civilised communities, 

 those that lead a life of activity in the open air 

 require far less protection from the cold than those 

 that live indoors. There is, besides, the greatest 

 difference in this respect between individuals, 

 though placed in exactly similar circumstances 

 a difference intimately connected with the sound- 

 ness of the digestion and other nutritive pro- 

 cesses. 



The feelings of buoyancy which most per- 

 sons in tolerable health experience during a clear 

 frosty day, have led to a general belief in the 

 peculiar healthiness of cold weather. But the 

 statistics of death and disease tell a different tale. 

 The Reports of the registrar-general shew that, 

 exactly as the thermometer sinks, the rate of mor- 

 tality rises, and certain diseases of the most fatal 

 kind become more prevalent ; the vitality, in short, 

 of the community decreases as the warmth of the 

 atmosphere decreases. We believe it to be an 

 31 



established fact, that the means generally taken 

 to arrest the waste of heat from our bodies, or 

 to supplement it, are, for the majority of men 

 and women, insufficient, or injudiciously managed. 

 This is a matter of literally ' vital ' moment to one 

 and all. The economy of heat is a primary ele- 

 ment in the art of living in health and comfort ; 

 and no ' knowledge of common things ' that we can 

 think of, can surpass in importance a right under- 

 standing of the principles and facts on which that 

 art rests. 



We have as yet spoken of arresting the dissi- 

 pation of the natural heat by clothing and shelter ; 

 and this, among some nations, is made to suffice. 

 Where fuel is scarce, the resource against the cold 

 of winter is thick clothing indoors as well as out. 

 This is said to be the regular practice in China ; 

 and even in the south of Europe, fires are dispensed 

 with in weather when we should think them abso- 

 lutely necessary, and additional wrappings are 

 considered as appropriate while sitting in the 

 house, as in the open air. But wherever fuel can 

 be had, it is always preferred to wear within doors 

 much the same clothing in winter as in summer, 

 and to keep the apartments nearly at summer tem- 

 perature by artificial heat It is this special 

 branch of the subject, namely, the artificial warm- 

 ing of apartments, that we are at present to 

 consider ; that of Clothing will be treated in a 

 subsequent number (see also PRESERVATION OF 

 HEALTH). 



In order to regulate temperature, we must first 

 know the nature of heat how it is produced, 

 and what laws it follows. This forms a branch of 

 the science of Physics, and has been briefly treated 

 in NATURAL PHILOSOPHY. But for the better 

 understanding of the present subject, it may be 

 well to say something more here of 



Combustion, 



Which is the chief source of artificial heat. Com- 

 bustion consists in the rapid union of the oxygen 

 of the air with some substance for which it has a 

 strong chemical attraction, and which is called a 

 combustible or fuel. All chemical combination 

 produces heat; but it is only called combustion 

 when the heat is so intense as to produce light. 

 The cheapest combustibles or fuels are coal, wood, 

 peat, coke, and charcoal, which consist chiefly of 

 two simple bodies or elements, carbon and hydro- 

 gen (see CHEMISTRY). Before oxygen will unite 

 with the combustible, the latter must be heated to 

 a high pitch ; the combustion once begun in one 

 part of the fuel, is then sufficient to keep the rest 

 at the combining temperature, provided the heat 

 is not too rapidly dissipated. One piece of fuel 

 will seldom keep alight alone ; a number of pieces 

 require to be burned together, in order to keep 

 one another warm. To blow cold air rashly into 

 a weak fire, puts it out, by suddenly cooling the 

 coal below the combining point. A cold poker 

 held near the flame of a candle will extinguish it ; 



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