ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
93 
Messrs. W. Watson and Sons’ No. 4 Van Heurck Microscope (B) 
(fig. 2). — Mounted on plain tripod foot, showing centering screws to 
stage. Height, when placed vertically and racked down, 13J in. The 
instrument is identical in all respects with the A and B forms, but 
is mounted on a different foot. 
Messrs. W. Watson’s Fine- Adjustment. — In calling attention to 
their system of fine-adjustment, Messrs. Watson write as follows:— 
“ The entire body [of the instrument] is raised or lowered by means of 
