236 Of the Quantities of Moisture^ ^c. 



in all seasons of the year, and never found the least in- 

 convenience from it. It is the warm bath of a perspira- 

 tion confined by a linen shirt, wet with sweat, which 

 renders the summer heats of the tropical climates so in- 

 supportable ; but flannel promotes perspiration, and 

 favours its evaporation ; and evaporation, as is well 

 known, produces positive cold. 



I first began to wear flannel, not from any knowledge 

 which I had of its properties, but merely upon the 

 recommendation of a very able physician (Sir Richard 

 Jebb) ; and when I began the experiments of which I 

 have here given an account, I little thought of discover- 

 ing the physical cause of the good effects which I had 

 experienced from it ; nor had I the most distant idea of 

 mentioning the circumstance. I shall be happy, how- 

 ever, if what I have said or done upon the subject 

 should induce others to make a trial of what I have so 

 long experienced with the greatest advantage, and which, 

 1 am confident, they will find to contribute greatly to 

 health, and consequently to all the other comforts and 

 enjoyments of life. 



I shall then think these experiments, trifling as they 

 may appear, by far the most fortunate and the most im- 

 portant ones I have ever made. 



With regard to the original object of these experi- 

 ments, the discovery of the relation which 1 thought 

 might possibly subsist between the warmth of the sub- 

 stances in question, when made use of as cloathing, and 

 their powers of attracting moisture from the atmosphere; 

 or, in other words, between the quantities of water they 

 contain, and their conducting powers with regard to heat, 

 I could not find that these properties depended in any 

 manner upon, or were in any way connected with, each 

 other. 



