178 



ELEMENTARY CHEMICAL MICROSCOPY 



able by micrometer screws attached to graduated drums D 1 , D 2 . 

 The pitch of the micrometer screws is identical in each instru- 

 ment. One complete revolution of a drum is an aliquot part 



FIG. 113. Beck Micrometer Microscope. 



of one division on the scale of the stage S 2 . The object to be 

 studied is placed upon the section S 1 of the stage and clamped in 

 place, the stage S having been first moved by hand by the knob 

 K to the most convenient place for beginning the measurements. 



