THE MICROSCOPE 65 



1. Leave the microscope in the case when not in use. Dust 

 works into the bearings of the instrument, making them 

 work hard and unnecessarily wearing them. 



2. When handling the microscope do not grasp it by the 

 arm which contains the fine adjustment unless the micro- 

 scope is designed to permit this. Grasp it by the pillar 

 below the stage. 



3. Never use alcohol on the lacquered parts. Rubbing 

 gently with a very little xylol and drying quickly will 

 remove any oily material. 



The Stage. The stage is that portion of the microscope 

 on which the mounted object is placed for examination. 



1. Should the stage become soiled with balsam, immer- 

 sion oil or anything which water will not remove, it can be 

 cleaned with xylol or chloroform. A little heavy oil will 

 restore the stage to its original black color. 



The Fine Adjustment. The fine adjustment is used for 

 bringing out details in very small objects and is necessarily 

 of limited range and delicate in its mechanism. 



1. If, when looking into the eye-piece, no change of focus 

 is noticed by turning the micrometer head, or if the microm- 

 eter head ceases to turn, the adjustment has reached its 

 limit. To adjust, focus down or up, respectively, with the 

 coarse adjustment, and turn the micrometer head until 

 the fine adjustment is midway within its range. 



2. When the fine adjustment screw stops, do not force it. 

 The Draw Tube. The draw tube is the tube receiving 



the ocular. 



1. The draw tube should work easily and smoothly. 

 On the draw tube will be found graduations in millimeters 

 or inches, some fixed point at which certain combinations 

 of objectives and oculars give the clearest image. This 

 differs with different microscopes and should be known for 

 the microscope used. 



The Nose-piece. The triple nose-piece on the compound 

 microscope serves a double purpose; to obviate the neces- 



