of the doable refraction in strained glass. 



327 



Table V. O 192. 

 B. C. D. 



E. 



Remarks on 192. 



A. July 6. Diaphragm central. Band observed for first extinction. 



B. July 7. No diaphragm used. „ „ „ „ „ 



C. July 7. Diaphragm central. „ „ „ „ „ 



D. July 8. „ „ „ „ „ second „ 



E. July 9. No diaphragm used. „ „ „ „ „ 

 [Band very black and well defined, throughout this set of 



observations.] 



