44 Inquiry concerning the Nature of Heat, 



Superficies of the cylindrical neck of the instrument 

 (= 0.8 X 3- I 4 I 59 X 4) 10.051 inches. 



Supposing, now, that the heat passes with equal ve- 

 locity through the surface of all the different parts of the 

 instrument, when the instrument is naked, we can deter- 

 mine the quantity of heat which escaped through the 

 ends and neck of the instrument in the experiments in 

 which those parts of the instrument were covered with 

 warm clothing. 



The whole of the metallic surface exposed to the air, 

 in the experiments made with the instrument when it 

 was quite naked, amounted to 85.195 superficial inches, 

 namely : 



Inches. 



Surface of its vertical sides, . . . .= 50.136 

 Surface of its lower end, . . . . =12.755 

 Surface of its upper end, . . . . . = 12.253 

 Surface of its neck, .....= 10.051 



Total surface, =85.195 



When the instrument was exposed quite naked to the 

 air, it was found to cool through the standard interval 

 of 10 degrees in 45^ minutes. 



Assuming, now, any given number as the measure of 

 the whole quantity of heat given off by the instrument 

 during the period above mentioned, we can ascertain 

 what part or proportion of that quantity passed off 

 through the sides of the instrument ; and what part of 

 it must have made its escape through its ends, and 

 through the sides of its neck. 



As the quantities of heat given off are supposed to 

 have been as the quantities of surface exposed to the 

 air, if we suppose the whole quantity of heat lost by 

 the instrument to be = 10,000 parts, the quantity which 



