BODY HEAT 59 



melt half a pound of ice or raise an equal weight of 

 water to boiling-point. This is a striking proof of the 

 danger of ' wet feet.' 



Even in respect of damp, wool is the best clothing 

 material, for, being far more hygroscopic than vegetable 

 fibre, it can absorb much more water without feeling wet. 

 Again, when thoroughly wet, only 26 per cent, of the 

 pores in wool are closed and their air displaced, whereas 

 in the case of silk the percentage is 39, and in linen as 

 high as 56. Wool is also difficult to wet both on account 

 of the natural oil which it contains and because of the 

 horny covering of its fibres. These advantages are well 

 illustrated in the case of Harris tweed. 



As regards the amount of clothing which should be 

 worn, all that can be said is that it should be sufficient 

 to prevent * an abiding feeling of cold.' As a rule, the 

 weight of the necessary clothes is from 6 to 12 pounds, 

 which may be easily doubled by the addition of an over- 

 coat and other outdoor apparel. Thus, in winter a man 

 may easily carry 18 per cent, of his weight on his back. 

 The lower animals are much more favourably situated 

 in this respect, for the weight of hair carried by a dog 

 weighing 9 pounds is only about 3 ounces. 



Small animals should, for reasons already given, be 

 more warmly clothed than large. Infants, therefore, 

 require abundance of clothing, and the * hardening ' 

 plan so foolishly advocated even by such a profound 

 thinker as Locke* is opposed to all the teaching of 

 physiology. 



* * Give me leave, therefore, to advise you not to fence too carefully 

 against the cold of this our climate. ... Be sure let not his [the 



