ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
853 
Microscope, together with the revolving stage, may be rotated through 
90° in either direction with respect to the central position. The front 
set-screws slide both together in a circular groove recessed into the re- 
volving strg>; the back set-screws slide in a separate elevated recess. 
This arrangement, in conjunction with the spring which binds the re- 
2 B 2 
