74 Prof. H. L. Callendar on the Thermodynamical 

 Constant-volume, zero correction, 



6 -T = U6C" + cJ Po /R. . . . 

 Scale correction, 



dt = C"t(t-100)/e, (47) 



Constant-pressure, zero correction, 



<9 -T = 846C" + 646C'-^ /R, . , 

 Scale correction, 



dt = (C (1-732 + 273/6) + Cy(t-l00)/6. 



The formulae are the same as before as regards c 

 additional terms are introduced to represent the effect of c'. 

 The numerical values of the constants are given in the following- 

 table as deduced from those calculated by Rose-Innes. 



(46) 



(48) 



(49) 

 ", but 



Table VII. — Values of Constants deduced from Formulae 

 of Rose-Innes. 



Gas 

 employed. 



b. 

 c.c. 



c.c. 



| 

 c ". C. 

 c.c. c 'p o /37SR. 



O". 



tY> /373K. 



Air 



Nitrogen . . . 

 Hydrogen ... 



1-62 



2 03 



1073 



1-89 

 2-09 

 1-19 



0-182 -00179 

 0-378 -00182 

 1 -45 -000078 



•00017 

 •00035 

 •000095 



The values of the scale-correction calculated by these 

 formulae for the constant-volume air-thermometer are about 

 five times smaller than those given in Table V., but the values 

 for the constant-pressure thermometer are nearly of the 

 same magnitude as those in Table V. In general we ma)' 

 observe that the corrections for the constant-pressure thermo- 

 meter are nearly independent of the type of formula assumed 

 within reasonable limits, and are therefore less uncertain than 

 those of the constant-volume thermometer. The values of C 

 and C /; given above correspond, as before, to an initial pressure 

 # = 76 cms. 



14. Variation of Specific Heats. 



The method followed by Joule and Thomson, and by the 

 majority of subsequent writers, has been to assume a formula 

 for the variation of the cooling-effect Q, which is then inte- 

 grated to find the constants in the characteristic equation, 

 neglecting the variations of the specific heat S. This is 

 perfectly justifiable in the case of the more permanent gases, 



