APPRECIATION OF TEMPERATURE. 13T 



temperature of that part of Virginia, is about 55J or 56 ; and that 

 the thermometer varies from 5J in the coldest month, to 94 in the 

 warmest. Now, the temperature of the human body being 98, it fol- 

 lows, that heat must be incessantly parting from us, and that we ought, 

 therefore, to experience constantly a sensation of cold; and this we 

 should unquestionably do, were we not protected by clothing, and aided 

 by artificial temperature during the colder seasons. Yet, accustomed 

 as the body is to give off caloric, there is a temperature, in which, 

 clothed as we are, we do not feel cold, although we may be disengaging 

 heat to some extent. This temperature may perhaps be fixed somewhere 

 between 70 and 80 in the climate of the middle portions of the United 

 States. So much, however, are our sensations in this respect dependent 

 upon the temperature which has previously existed, that the comfortable 

 point varies at different seasons. If the thermometer, for instance, has 

 ranged as high as 98, and has maintained this elevation for a few days, 

 a depression of 15 or 20 will be accompanied by feelings of discom- 

 fort ; whilst a sudden elevation from 30 to 75 may occasion an op- 

 pressive feeling of heat. In northern Siberia, M. von Wrangel 1 found, 

 that only a few degrees of frost was currently denominated "warm 

 weather;" and that after having been accustomed to the winter tempe- 

 rature of that climate, it seemed to him, that 10 of cold, 22 below 

 the freezing point of Fahrenheit, was a mild temperature. During the 

 voyages, made by Captain Parry and others to discover a northwest 

 passage, it was found, that after having lived for some days in a tempe- 

 rature of 15 or 20 below 0, it felt comfortable when the thermometer 

 rose to zero. 



These are the great sources of the deceptive nature of our sensations 

 as to warmth and cold which enable us to judge merely of the com- 

 parative conditions of the present and the past ; and hence it is, that 

 a deep cellar appears warm in winter and cold in summer. At a certain 

 distance below the surface, the temperature of the earth indicates the 

 medium heat of the climate ; yet, although this may be stationary, oiu* 

 sensations on descending to it in winter and summer would be by no 

 means the same. If two men were to meet on the middle of the South 

 American Andes, the one having descended, and the other ascended, 

 their sensations would be very different. The one, who had descended, 

 coming from a colder to a warmer atmosphere, would experience warmth ; 

 whilst the other, who had ascended, would feel correspondently cool. 

 An experiment, often performed in the chemical lecture-room, exhibits 

 the same physiological fact. If, after having held one hand in iced, 

 and the other in warm water, we plunge both into water of a medium 

 heat, it will seem warm to the one hand, and cold to the other. 



But our sensations are not guided solely by bodies surrounding us. 

 They are often greatly dependent, especially in disease, on the state of 

 the animal economy itself. If the power, which the system possesses 

 of forming heat, be morbidly depressed or if, in consequence of old 

 age, or of previous sickness, calorification does not go on regularly and 

 energetically, a temperature of the air, which to the vigorous is agree- 



1 Reise des kaiserlich Russischen Fiotten Lieutenants F. v. Wrangel, langs der Nordkiiste 

 von Siberien, u. s. w. Berlin, 1839, translated in Harper's Family Library. 



