POPULAR FALLACIES. 



the foot, and therefore, though at a higher temperature than the 

 body, creates no sensation of warmth. The tiles and marble, 

 being better conductors of heat, and at a higher temperature 

 than' the body, transmit heat readily, and metallic objects still 

 more so : these, therefore, feel hot. On passing into a cold 

 room, the very contrary effects ensue. Here all the objects have 

 a temperature below that of the body ; the ca'rpet and other bad 

 conductors, not being capable of receiving heat when touched, 

 produce no sensation of cold ; wood, being a better conductor, 

 feels cooler ; marble, being a better conductor, gives a still 

 stronger sensation of cold ; and metal, the best of all conductors, 

 produces that sensation in a still greater degree. 



In cold temperatures, the particles of water which carry off 

 the heat from the body are far more numerous than those of air, 

 and therefore carry the heat off more rapidly ; and, besides, they 

 are constantly changing their position ; the particles warmed by 

 the body immediately ascend by their levity, and cold particles 

 come into contact with the skin. Thus water, although a bad 

 conductor of heat, has the same effect as a good conductor, by 

 the effect of its currents. 



Sheets feel colder than the blankets, because they are better 

 conductors of heat, and carry off the heat more rapidly from the 

 body ; but when, by the continuance of the body between them, 

 they acquire the same temperature, they will then feel even 

 warmer than the blanket itself. Hence it may be understood 

 why flannel, worn next the skin, forms a warm clothing in cold 

 climates, and a cool covering in hot climates. 



To explain the apparent contradiction implied in the fact that 

 the use of a fan produces a sensation of coldness, even though 

 the air which it agitates is not in any degree altered in tempera- 

 ture, it is necessary to consider that the air which surrounds us 

 is generally at a lower temperature than that of the body. If 

 the air be calm and still, the particles which are in immediate 

 contact with the skin acquire the temperature of the skin itself, 

 and, having a sort of molecular attraction, they adhere to the 

 skin in the same manner as particles of air are found to adhere 

 to the surface of glass in philosophical experiments. Thus 

 sticking to the skin, they form a sort of warm covering for it, 

 and speedily acquire its temperature. The fan, however, by 

 the agitation which it produces, continually expels the particles 

 thus in contact with the skin, and brings new particles into that 

 situation. Each particle of air, as it strikes the skin, takes heat 

 from it by contact, and, being driven off, carries that heat with 

 it, thus producing a constant sensation of refreshing coolness. 



Now from this reasoning it would follow that, if we were 

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