474 HENEY A. ROWLAND 



The reduction to the air thermometer was made for the temperatures 

 of 9 C. and 11 C. respectively, but they both refer to the temperature 

 of the water used when the capacity was determined; this was about 

 9 C. Hence these experiments gave 427-5 and 428-7 on the air ther- 

 mometer, with the water at about 9 C. 



The next experiments, with cast-iron, can be corrected in the same 

 manner, and thus become 



776-0 773-9 



Correction for thermometer 4-2 4-3 



Correction for capacity 1*1 !! 



Correction for latitude -9 -9 



782-2 780-2 



and these are as before for water at 9. 



The determination by the heating of a wire, whose resistance was 

 measured in ohms, can be thus reduced. The value found by Joule 

 was 429-9 in the latitude of Baltimore at 18 -6 C. 



Using the capacity of the copper -0922, as I have done in my paper, 

 this quantity will be increased to 430-3. But I have given reasons in 

 my paper on the " Absolute Unit of Electrical Resistance " to show that 

 there should be a correction to the B. A. Committee's experiments, 

 which would make the ohm -993 earth quadrant -f- second, instead of 

 1-000 as it was meant to be, which nearly agrees with the quantity 

 which I found, namely, -991. Taking my value -9911, Joule's result 

 will reduce as follows : 



429.9 at 18 -6 C. 



Correction for thermometer -|- 1-5 



Correction for capacity -|- -4 



Corrected for ohm 3-8 



Corrected value 428-0 at 18 -6 C. 



The last determinations in the ' Philosophical Transactions ' of 1878 

 can be reduced as follows : 



The capacity of the calorimeter was determined by experiment, in- 

 stead of calculated from the specific heat of copper given by Regnault, 

 as in the older experiments. The value used, 4842-4 grains, corre- 

 sponded to a specific heat of brass of about -090, which is almost exactly 

 what I have considered right. The reduction to the air thermometer 

 will decrease it somewhat, and the correction for the increase of the 



