236 THE HISTORY AND DEVELOPMENT OF THE MICROSCOPE 



rack and pinion, while the fine adjustment is the now celebrated 

 lever employed by this firm. One revolution of the milled head 



FIG. 189. Watson's ' Fram ' microscope (1898). 



moves the body the ^^th of an inch. As we have seen (p. 170, 

 fig. 132), this adjustment is sound in principle, and in practice all 



