CHAPTEE VII 



THE USE AND MANIPULATION OF THE MICROSCOPE 



Essential Adjustments. It is, above all things, necessary that 

 the microscope and its optical parts should be in perfect adjust- 

 ment, as on this more than on any elaboration of apparatus 

 will depend the excellence of the results. It does not come 

 within the scope of this work to go fully into the theory and 

 practice of microscopy, and reference must be made to one of 

 the standard works a list of which is given in Appendix VI 

 if fuller information is required. Sufficient will be said, 

 however, to enable one who already has some knowledge of 

 the microscope and its use, to make the necessary adjustments. 

 The matter will be treated from the standpoint that the optical 

 portion of the microscope consists essentially of the three parts 

 already enumerated : 



The objective, which forms the actual microscope image; 

 The eye-piece, which more or less amplifies this image ; 

 The sub-stage condenser, to illuminate the object efficiently. 



It will be assumed that some very simple object presenting 

 no particular difficulty, preferably without colour and the 

 image therefore only being formed as the result of light obstruc- 

 tion, is first placed upon the microscope stage. A low-power 

 objective for example, a 1-inch should be screwed into position 

 on the instrument. The sub-stage condenser had better for 

 the moment be removed and illumination be effected by re- 

 flecting light from the plane side of the mirror. The illuminant 

 may be placed in a convenient position say, some eight to ten 

 inches away from the mirror and the latter adjusted so that the 

 light is reflected on to the object. On observing the image 



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