ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



643 



f «(" The present Microscope formerly belonged to my great-uncle, 

 Charles Gamier, who died in 1869, since when it has been in my posses- 

 sion — it was my t first Microscope." — C.F.R.) 



Fig. 80. 



Simple Improvements for a Petrographical Microscope.* — Under 

 the above title, A. Johannsen suggests four advantageous improvements. 



1. A rotating upper nicol in which the annoying reflection of light from 

 the surface is overcome. In examining, between cross nicols, minerals 

 which are rather dark, a small amount of light falling upon the upper 



* Amer. Journ. Sci., xxix. (1910) pp. 435-8 (i figs.). 



