146 



ELEMENTARY CHEMICAL MICROSCOPY 



The drums D 1 , D 2 , are set at zero; the point or line on the object 

 from which measurements are to start is brought exactly under 

 the cross-hairs of B by means of M 2 ; the exact position with 

 respect to the scale is determined by the reading microscope A 



FIG. 92. Reichert Micrometer Microscope. 



with great accuracy, using the ocular micrometer. The entire 

 stage is next displaced, by hand or by the screw M 2 , to the right 

 or left, as the case may be, until the second point is reached and 

 the scale again read. 



In order to vary the magnification of the observing microscope 

 B, the objective is mounted so as to slide up and down in the 

 body tube. A double-ended pointer P attached to the objective 

 mounting moves over two scales, one of which indicates the mag- 

 nification, the other the ocular micrometer value of the drum D 1 . 

 Microscope B is focused by means of the pinion F, light being 

 thrown by the mirror through the preparation to be examined. 



