30 W. J. M. Rankine, Esq., on the Elctsticily of Vapours. 



cury, and the temperatures in centigrade degrees of the air- 

 thermometer : — 



Log. y — 5-0827176 Log. /S = 31851091 



a.— 7-831247. 



Table I. exhibits a comparison between the results of the 

 formula and those of M. Regnault's experiments, for every 

 tenth degree of the centigrade air-thermometer, from 30° be- 

 h)w the freezing point to 230° above it, being within one or 

 two degrees of the whole range of the experiments. 



M. Regnault's values are given, as measured by himself, 

 onthecurves representingthe mean results of his experiments, 

 •with the exception of the pressures at 26°-86, one of the data 

 already mentioned, and that at — 30°, which I have calcu- 

 lated by interpolation from his Table, series /*. 



Each of the three data used in determining the constants 

 is marked with an asterisk*. 



In the columns of differences between the results of the 

 formula and those of experiment, the sign + indicates that 

 the former exceed the latter, and the sign — the reverse. 



Beside each such column of differences is placed a column 

 of the corresponding differences of temperature, which would 

 result in calculating the temperature from the pressure by 

 the inverse formula. These are found by multiplying each 



number in the preceding columns by — [^-p, or by ^i i.^cr. p as 

 the case may require. 



