CHAPTER V 



THE MICROSCOPE 

 (Fig. 19) 

 The compound microscope is a necessary adjunct to 

 any kind of bacteriological work. For this work three 

 objectives (Leitz No. 3, No. 6, or No. 7 and ^^ oil im- 

 mersion, Zeiss No. A or No. AA, No. D or No. DD, and 

 ^ oil immersion) and two oculars (Nos. 2 and 4) are 

 indispensable. For the intelligent manipulation of the 

 microscope it is absolutely necessary to understand the 

 underlying optical principles, which may be studied from 

 special works on the subject. 



Re/erences — 



S. H. Gage, The Microscope. 



Carpenter and Dallinger, The Microscope and its Revelations. 



For use in the laboratory it will be sufficient to call 

 attention to some of the most important points to be 

 observed. 



The usual pattern of microscope consists of two main 

 parts: the stand, and the optical parts (Fig. 19) which 

 are attached to the stand. 



The stand consists of a body-tube, draw-tube, coarse 

 adjustment, fine adjustment (micrometer screw) in a 

 pillar, nose-piece, stage with clips for holding the object, 

 main pillar, and the horseshoe base. At the junction 

 of the main pillar and the fine-adjustment pillar is the 

 inclination joint. 



The draw-tube, regulating the focal length, which 

 varies in different instruments, should be raised to 16 



