4o8 Of the P ropagation of Heat 



iS'^ to 27°. After 4 minutes had elapsed, it had risen 

 to 44W ' ^^'^ ^^ ^^ ^^^ °^ 5 minutes it had risen to 

 48Vo' 



Experiment No. 1. 



Taking it now out of the boiling water I suffered it to 

 cool gradually in the air, and after it had acquired the 

 temperature of the atmosphere, which was that of 15° R. 

 (the weather being perfectly fine), I broke off a little 

 piece from the point of the small tube which remained 

 at the bottom of the glass ball, where it had been her- 

 metically sealed, and of course the atmospheric air 

 rushed immediately into the ball. The ball surround- 

 ing the bulb of the thermometer being now filled with 

 air (instead of being emptied of air, as it was in the 

 before-mentioned experiment), I resealed the end of the 

 small tube at the bottom of the glass ball hermetically, 

 and by that means cut off all communication between 

 the air confined in the ball and the external air ; and 

 with the instrument so prepared I repeated the experi- 

 ment before mentioned, that is to say, I put it into 

 water warmed to 18^, and when it had acquired the 

 temperature of the water, I plunged it into boiling 

 water, and observed the times of the ascent of the mer- 

 cury in the thermometer. They were as follows : — 



Heat at the moment of being plunged into 

 the boiling water 



After having remained in the boiling water 



