THE MICROSCOPE 



The microscope is a delicately adjusted instrument and great 

 care should be exercised in using it to keep it in good condition. 

 The following rules should be observed: 



1. When not in use keep in the case. Dust causes unusual 

 wear if allowed to work into the mechanism. 



2. Alcohol should never be used on the lacquered parts. If 

 oily material is to be removed use xylol with gentle rubbing. 



3. Should the stage or objectives become gummed with im- 

 mersion oil or balsam it can be removed with lens paper moistened 

 with xylol. 



4. Use the plane mirror for daylight and the concave for arti- 

 ficial light. 



5. Regulate the amount of light by raising or lowering the 

 Abbe condenser. This is done with a screw under left of stage. 

 The higher the condenser the greater the amount of light. Dust 

 in the eyepiece makes the field appear covered with specks. Wipe 

 with lens paper. 



6. Do not touch the surface of the lens with the fingers. 



7. Objectives of one microscope should not be changed to 

 another even of the same make. 



8. To focus with the two highest powered objectives place 

 object to be examined in center of stage. With eyes at the side 

 at the level of the stage lower the objective w r ith the coarse adjust- 

 ment until it nearly touches the cover glass. Adjust mirror and 

 condenser to give desired amount of light. Focus slowly upward 

 with the fine adjustment until the object becomes clear. With the 

 1/12 or oil immersion objective a drop of cedar oil between the 

 lens and the cover glass is necessary to prevent dispersion of light. 



9. The fine adjustment is used for bringing out details in 

 very small objects consequently has a limited range and is me- 

 chanically delicate. When the fine adjustment screw stops do not 

 force it. 



10. Never use oil with any but the oil immersion objectives. 

 With Leitz microscopes the 1/12 objectives (oil immersion) are 

 copper colored with nickel end. With Bausch & Lomb microscopes 

 the oil immersions are nickeled on the lower half. 



11. For measuring bacteria a finely ruled scale is used. This 

 is placed ruled side down in top part of eyepiece. The eyepiece may 

 be swung around to make the scale lie in any direction desired. 

 There are ten microns between each of the numbers on the scale. 



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