INTRODUCTION 25 



4. Use and Care of the Microscope. Having learned the 

 parts and adjustments of the instrument practice their 

 use until they become familiar. This is especially im- 

 portant in the adjustments relating to light. Test manip- 

 ulation of mirrors and diaphragms until able to obtain 

 and control just the amount and quality of light essential 

 to the best effects, doing so with eye constantly at the ocular. 

 The best light is that of the open sky (not sunlight direct) 

 or that reflected from bright clouds. Artificial light may 

 be used provided a screen of some sort be interposed, such 

 as a bluish, or ground glass. Begin every study with the 

 low power, nothing is gained by using a higher power than 

 serves the end in view. 



To avoid eye fatigue while using the microscope practice 

 looking with both eyes open, which after a little practice 

 is not especially difficult. If not easily acquired, an artificial 

 shade or screen may be used as may be explained by the 

 instructor. 



Proper care of the microscope is important if its efficiency 

 is to be at its best. Keep every part clean, do not allow 

 water, or dirt, or chemicals, to remain in contact with any 

 of its parts. This is especially important for the lenses. 

 Do not touch the lenses with the naked finger, and if they 

 should appear dirty cleanse with lens paper furnished by 

 the laboratory. This may be facilitated by breathing on 

 the lens and then gently wiping dry. 



Never attempt to take lenses apart. 



