Introduction. xvii 



of the coarse adjustment ; look through the eyepiece and slowly 

 raise the tube until you see the object distinctly. Move the 

 slide till the object, or the part you wish to examine, is in 

 the center of the field of view. Now use the fine adjustment. 

 Never turn the milled head of the fine adjustment more than 

 two or three turns in either direction. 



Use of a High-power Objective. Begin as with the use of a 

 low-power objective. Lower the tube until the objective almost 

 touches the cover glass, watching closely with your head 

 down on a level with the stage. Look through the eyepiece ; by 

 means of the coarse adjustment, slowly raise the tube till the 

 object comes into view. Then use the fine adjustment till the 

 outlines become sharp and distinct. Be very careful not to run 

 the objective against the cover glass. If you do this, you may 

 ruin the preparation and injure the lens. 



The Diaphragm. Use an opening in the diaphragm of about 

 the same size as the front lens of the objective. 



Use of the Eyes. Always keep both eyes open when using a 

 microscope. This may be a little confusing at first, but you will 

 soon learn to ignore what the other eye sees. 



Read " Practical Methods in Microscopy," Clark (D. C. 

 Heath & Co.). 



PARTS OF A MICROSCOPE. 



A. Base. J. Coarse adjustment. 



B. Pillar. K. Milled head of coarse adjustment. 



C. Arm. L. Micrometer screw of fine adjustment. 



D. Body. M. Stage. 



E. Nose piece. N. Clips. 



F. Objective. O. Mirror. 



G. Eyepiece. P. Mirror bar. 

 H. Draw tube. Q. Substage. 

 I. Collar. S. Diaphragm. 



