354 



HENRY A. ROWLAND 



Regnault's results are embodied, for the most part, in tables given on 

 p. 239 of the first volume of his Relation des Experiences. The figures 

 given there are obtained from curves drawn to represent the mean of 

 his experiments, and do not contain any theoretical results. The direct 

 application of my formula to his experiments could hardly be made with- 

 out immense labor in finding the most probable value of the constants. 



But the following seem to satisfy the experiments quite well: 



Cristal de Choisy-le-Roi b = 0, 



Verre Ordinaire b = 245, 



Verre Vert b = 270, 



Verre de Suede b = +10 



a = .000 000 32. 

 \ = .000 000 34. 

 a = .000 000 095 

 a .000 000 14. 



From these values I have calculated the following: 



TABLE II. REGNAULT'S RESULTS COMPARED WITH THE FORMULA. 



The formula, as we see from the table, represents all Eegnault's 

 curves with great accuracy, and if we turn to his experimental results 

 we shall find that the deviation is far within the limits of the experi- 

 mental errors. The greatest deviation happens at 340, and may be 

 accounted for by an error in drawing the curve, as there are few experi- 

 mental results so high as this, and the formula seems to agree with 

 them almost as well as Regnault's own curve. 



3 Corrected from 280-52 in Regnault's table. 



