POPULAR FALLACIES. 



water at 90 will feel cold. If, therefore, the touch be in this 

 case taken as the evidence of temperature, the same water \vill 

 be judged to be hot and cold at the same time. 



I have elsewhere indicated several curious examples of the 

 fallacies of the senses of feeling in relation to the temperature 

 of bodies.* 



Even when the state of our bodies is the same, and the tem- 

 perature of external objects the same, different objects will feel 

 to us to have different degrees of heat. If we immerse the naked 

 body in a bath of water at the temperature of 120, and, after 

 remaining for some time immersed, pass into a room in which 

 the air and every object is raised to the same temperature, we 

 shall experience, on passing from the water into the air, a sensa- 

 tion of coldness. If we touch different objects in the room, all 

 of which are at the temperature of 120, we shall nevertheless 

 acquire very different perceptions of heat. When the naked 

 foot rests on a mat or carpet, a sense of gentle warmth is felt ; 

 but if it be removed to the tiles of the floor, heat is felt sufficient 

 to produce inconvenience. If the hand be laid on a marble 

 ehimney-piece, a strong heat is likewise felt, and a still greater 

 heat on any metallic object in the room. Walls and woodwork 

 will be felt warmer than the matting, or the clothes which are 

 put on the person. Now, all these objects are, nevertheless, at 

 the same temperature. From this chamber let us suppose that 

 we pass into one at a low temperature ; the relative heats of all 

 the objects will now be found to be reversed the matting, 

 carpeting, and woollen objects, will feel the most warm ; the 

 woodwork and furniture will feel colder ; the marble colder still ; 

 and "metallic objects the coldest of all. Nevertheless here, again, 

 all the objects are exactly at the same temperature, as may be 

 in like manner ascertained by the thermometer. 



In the ordinary state of an apartment, at any season of tlio 

 year, the objects which are in it all have the same temperature, 

 and yet to the touch they will feel warm or cold in different 

 degrees : the metallic objects will be coldest ; stone and marble 

 Jess so ; wood still less so ; and carpeting and woollen objects 

 will feel warm. 



When we bathe in the sea, or in a cold bath, we are accus- 

 tomed to consider the water as colder than the air, and the air 

 colder than the clothes which surround us. Now all these objects 

 are, in fact, at the same temperature. A thermometer, surrounded 

 by the cloth of our coat, or suspended in the atmosphere, or 

 immersed in the sea, will stand at the same temperature. 



* Treatise on Heat, p. 372. 

 92 



