32 Inquiry concerning the Nature of Heat, 



As it sometimes happened, though very seldom, in 

 the course of an experiment (which commonly lasted 

 several hours) that I was called away, and was not pres- 

 ent to observe the thermometer at the moment of the 

 passage of the mercury through one or both of those 

 points of its scale which formed the limits of the given 

 interval chosen as the standard for a comparison of the 

 results of the experiments with each other, it became a 

 matter of considerable importance to find means for 

 supplying these accidental defects, and ascertaining the 

 points in question by interpolation. 



In order to facilitate the means of doing this, I en- 

 deavoured to investigate the law of the cooling of hot 

 bodies in a cold fluid medium ; and I found reason to 

 conclude, 



M 



That if, on the right line AB, a perpendicular CD be 

 taken, equal to the difference of the temperatures of the 

 hot body and of the colder medium, expressed in de- 

 grees of the thermometer ; and, after a certain given 

 time, represented by CE, taken on the line AB at the 



