106 



INTERFEROMETRY OF SPECTRA. 



and iJ.=x-\-2B/\ 2 . Data of this kind are given in table 29, the absolute values 

 depending wholly on the correctness of the thickness E of the solution and 

 e for the submerged lens. The ellipses were excellent, sharp, and strong. 

 H i-\-2B'/\ 2 is found directly and A/V is negative as the solution is stronger. 



TABLE 29. Refraction of lenses. D line. Thickness of solution, =0.563 

 cm. ;K' = n'-i +2B'/\ 2 ; 2B/\ 2 = 0.0260 for glass. M - 1 =K'-AN/e. 



* Probably not adequately centered. 



But such a method is not as convenient as was anticipated at the outset, 

 while it may fall short of the needed accuracy if rigorously carried out. The 

 only escape out of the difficulty would be the use of a liquid of about the 

 same dispersion constants as the glass. In this case the corrections would 

 be minimized and the experimental work simpler. 



