OF ARTS AND SCIENCES. 46 



Joule's value is less than my value to the amount given, but the 

 value from the properties of air, 430.7 at l-i° C. is greater, although 

 the method can have little weight. 



It might be well to diminish my values by 1 part in 1000 so as to 

 make them represent the mean of Joule's and my own experiments. 

 It is seen that the experiment by the method of electrie heating agrees 

 very exactly with the other experiments, because I have reduced it to 

 my value of the ohm. Hence I regard it as a very excellent confirma- 

 tion of my value of that unit. 



Baltimore, Feb. 16, 1880. 



