EXERCISE 17 (Continued) 



CAUTION. From the very first use of the microscope keep both eyes open. If you attend to what 

 you see inside the microscope, what the other eye sees will not disturb you. Keeping both eyes open 

 avoids straining the eyes. 



Place the prepared slide on the stage, with the object as near the center of the hole in the diaphragm 

 as possible. 



Look through the eyepiece and gently raise the tube, with the coarse adjustment, until you see a 

 clear image. By turning gently back and forth with the fine adjustment you may get a sharper focus. 



After the object is in focus you may try to improve the illumination by gently moving the mirror 

 back and forth in various directions and by trying smaller and larger openings of the diaphragm. 



After making the drawing get a view through the high power as follows : while the object is 

 sharply in focus turn the nosepiece carefully to bring the other objective in line with the tube ; listen 

 or feel for the click which indicates that the objective is centered. Then look through the eyepiece 

 and gently adjust with the fine adjustment. 



CAUTION. Always begin focusing upward, and guard against bringing the objective in contact with 

 the cover glass. 



Questions. 1. Why is more light needed for study with the high power than for study with the 

 low power ? 



2. Who invented the microscope ? 



[19] 



