622 



Mr. C. Y. Raman on the Photometric 

 Table III. 



Positions on the plate of 



The Direct image 



Observed. 



Calculated. 



8-4837 



8-4837 



2nd Broad Dark Band . . . 



8-8330 



8-8332 



1st ., ,, ,, 



8-8861 



8-8857 



1st Narrow „ „ 



8-9610 



8-9602 



2nd „ „ 



8-9898 



8-9903 



3rd „ 



9-0166 



9-0175 



Table IY. 



Positions on the plate of 



The Direct image 



Observed. 



Calculated. 



7-0966 



7-0966 



Srd Broad Dark Band 



8-2190 



8-2191 



2nd „ „ 



8-3186 



8-3187 



J-St ii >> it 



8-4010 



8-4025 



1st Narrow „ „ 



8-5424 



8-5427 



2nd „ ,. „ 



8-6028 



8-6038 



3rd „ 



8-6622 



8-6607 



4th 



8-7164 



8-7141 



i 



The measurements do not reveal any decided departure from 

 theory, of the positions of the minima of illumination. 



The considerations advanced above seem to me to be 

 sufficient proof of the general correctness of the explanation 

 suggested by me. I realized, however, that actual measure- 

 ments of the obliquity-effects would form a more conviucing 

 proof, and at the same time would have intrinsic experi- 

 mental interest and serve also to test the correctness of the 

 mathematical work. 



There are two classes of obliquity- effects, which in practice 



