E. M. NELSON ON EVOLUTION OF THE MICROSCOPE. 117 



the objective on the nose-piece. The thumbscrew is then clamped 

 tight, and further focussing performed by the fine adjustment 

 DC. This microscope is very similar in design to that of 

 J. Marshall (see Part 1, Fig. 9, p. 355), excepting the important 

 addition of a mirror ; it is however better finished and not so 

 unwieldy. It will be noticed that both are body focussers in 

 contradistinction to the stage focussers so much in vogue at 

 that date. There is one novel feature in the mounting of the 

 Lieberkuhn (E, Fig. 23), which hasabeady been explained above. 

 The date of this microscope is 1744. 



