448 



Of the Propagation of Heat 



The differences of the times of cooling in these three 

 experiments were extremely small ; but regular as these 

 experiments appear to have been in their results, they 

 were not more so than the other experiments made in 

 the same way, many of which were repeated two or three 

 times, though, for the sake of brevity, I have put them 

 down as single experiments. 



But to proceed in the account of my investigations 

 relative to the causes of the warmth of warm cloathing. 

 Having found that the fineness and equal distribution 

 of a body or substance made use of to form a covering 

 to confine Heat contributes so much to the warmth 

 of the covering, I was desirous, in the next place, to 

 see the effect of condensing the covering, its quantity 

 of matter remaining the same, but its thickness being 

 diminished in proportion to the increase of its density. 



The experiment I made for this purpose was as fol- 

 lows : I took 16 grains of common sewing-silk, neither 

 very fine nor very coarse, and winding it about the bulb 

 of the thermometer in such a manner that it entirely 

 covered it, and was as nearly as possible of the same 

 thickness in every part, I replaced the thermometer in 

 its cylinder and globe, and heating it in boiling water, 

 cooled it in ice and water, as in the foregoing experi- 

 ments. The results of the experiment were as may be 



