96 Mr. Her apath on True Temperature, and the [Aug. 



This table 1 computed from the subsequent account of Dulong 

 and Petit's observations, extracted from vol. xiii. of the Annals 

 of Philosophy. 



Temp, indicated by mercurial ther- Temp, indicated by air thermometer 



mometer in centigrade. corrected for dilatation of glass. 



- 36° - 36-00° 



0-0 



100 100-0 



150 148-70 



200 197-05 



250 245-05 



300 292-70 



360 300-00 



In the 48th volume of the Philosophical Magazine, I find the 

 numbers in the higher ranges are different. I have not this 

 volume at hand ; and, therefore, cannot tell whether Dr. Thom- 

 son and Mr. Tilloch refer to the same or different experiments of 

 Dulong and Petit. The numbers in the 48th volume of the 

 Philosophical Magazine, as sent me by my cousin Mr. William 

 Herapath, stand thus : 



Merc, therm, centigrade. Air therm, centigrade. 

 100 lOO'OO 



150 148-70 



200 197-05 



250 244-17 



300 291-77 



N.B. When interpolating the observations of Dulong and 

 Petit, I perceived the whole of them, except the last, were con- 

 nected by a law, which, being very simple, and differing not 

 more than a degree of Fahrenheit from their last observation at 

 680°, the boiling point of mercury, I have thought it better to 

 continue than to render the table discontinuous. 



Table V. 



True Temperature. 

 The following table, calculated from the preceding, exhibits 

 the corrections necessary to reduce the temperature of the 

 common mercurial thermometer to the air thermometer, sup- 

 posing them divided, according to the law of temperature, as 

 resulting from our theory of heat. 



