60 



THE MICROSCOPE AND ITS REVELATIONS. 



rack-movement with double milled-head, is swung on two uprights set 

 on a solid foot, in such a manner as to be well balanced; and at the top 

 of the racked stem is the milled-head that works the screw for fine 

 adjustment, raising or lowering the horizontal arm which carries the 

 body, without twist or loss of time. This arm carries a tube firmly 

 screwed into it, through which the body slides; and while this arange- 

 ment, by giving additional support to the lower part of the body, effect- 

 ually antagonizes vibration, it allows the body to be raised to a height 

 that permits the use of objectives of 3 or 4 inches' focus, for which the 

 rack-movement is not long enough to provide. On the outside of this 

 tube is a clip having attached to it a jointed arm that carries a condens- 



FIG. 43 



Pillischer's International Microscope. 



Ross's (Zentmayer) Student's Microscope. 



ing lens for opaque objects; which, by raising or lowering the clip, or 

 turning it round the tube, can be brought into any required position. 

 The stage is simple, and carries a rotating diaphragm-plate on its under 

 side. The mirror is attached to a swinging bar, which might easily be 

 made to elongate like that of the Wale Microscope ( 60). The special 

 merit of this model (of which the Author can speak from considerable 

 experience of its use), lies in the facility with which both the coarse and 

 the fine movements may be worked with either of the hands, while rest- 

 ing on the table in the position most convenient for manipulating the 



