21 



APPENDIX TO PAPEE ON THE MECHANICAL EQUIVALENT 

 OF HEAT, CONTAINING THE COMPARISON WITH DR. 

 JOULE'S THERMOMETER 



[Proceedings of the American Academy of Arts and Sciences, XVI, 38-45, 1881] 

 Presented, March, 1880 



In the body of this paper I have given an estimate of the departure of 

 Dr. Joule's thermometer from the air thermometer, based on the com- 

 parison of thermometers of similar glass. But as it seemed important 

 that the classical determinations of this physicist should be reduced to 

 some exact standard, I took to England with me last summer one of 

 my standards, Baudin, No. 6166, and sent it to Dr. Joule with a 

 statement of the circumstances. He very kindly consented to make 

 the comparison, and I now have the results before me. These confirm 

 the estimate that I had previously made, and cause our values for the 

 equivalent to agree with great accuracy. The following is the table of 

 the comparison : 



1 Evidently a mistake in the readings. 



