138 THE HISTOIJY AND DEVELOPMENT OF THE MICEOSCOPE 



scopical construction \\ere here ciiil >i idled. (1) A fine-adjustment 

 screw !' i- connected with the sliding socket E, supporting the arm 

 \>. in \\hich ilit- body-tube is screwed; the focussing could thus be 

 controlled in ,-i far mure effective manner than by any system pre- 

 viously applied to ,-i l;irgc microscope-. The previous systems involved 

 the direct movement of the hody-tube either by rotating in a screw- 

 socket (a> in Hooke'>) or 1 iv sliding in a cylindrical socket (as in 

 Divini's and Cherubin's) ; in a few instances the object was moved 



'' '' 



i; - M. Joblot's inicni -r,.p ( . (1718 



lation to the objed lens, but all these plans were more or less 



vrith microscopes of large dimensions. Marshall's 



" 1|H mechanica] improvement, for the object could 



luring the actual process of focussing, as the ima<-e 



"Klj in the field. (2) A fork. X X. is here applied 



'lamp, 0, on the pillar itself. (3) Hooke's ball- 



ww applied to the arm I. is here shifted to 



; Pillar, where i, would give the movements of 



'microscope instead of to the body tub,- only, 



