290 



Of the Propagation of Heat 



when the hot water was poured into the ice, and when 

 the paper which covered the ice was removed, were in a 

 great measure prevented. 



In order that the water which was poured through the 

 wooden tube (the bore of which was about half an inch 

 in diameter) might not impinge perpendicularly and with 

 force against the bottom of the dish, the lower end of 

 the tube was closed by a fit cork-stopple, and the water 

 was made to issue horizontally through a number of 

 small holes in the sides of this tube, at its lower end. 



As soon as the operation of pouring the hot water 

 into the jar was finished, the perforated dish was care- 

 fully removed, and the jar was covered with a circular 

 wooden cover, from the center of which a small mercurial 

 thermometer was suspended. 



The effects produced by this new arrangement of the 

 machinery will appear by comparing the results of the 

 two following experiments with those just mentioned. 



In order still more effectually to prevent the inaccura- 

 cies arising from the internal motions in the mass of hot 

 water which were occasioned in pouring the water into 

 the jar (and which could not fail to affect, more or less, 

 the results of the experiment), I had recourse to the 

 following contrivance. 



I filled a small phial containing 8^ cubic inches with 

 ice-cold water, and then, emptying the phial in the jar, I 

 covered the surface of the ice with this ice-cold water to 

 the height of 0.478 of an inch. 



