x THE COMPOUND MICROSCOPE. 
tube, slightly turn it at the same time. Such 
rapid movement is called the coarse adjustment. 
Some microscopes have a “rack and pinion” for 
greater convenience in the coarse adjustment. 
Which has yours ? 
7. Usually at the top of the column is a “milled head” 
of a screw, which, by being turned, moves the 
tube a very short distance. This is called the fine 
adjustment. 
B. The Lenses. 
1. The eye-piece, or ocular, consists of lenses mounted 
in a cylinder of metal. Hold it near the eye and 
look through it toward the light, and observe the 
area of light. Are objects easily seen through it? 
To be of use it is placed in the upper end of the 
tube, and is usually left in this position. 
2. The objective consists of lenses mounted in a some- 
what conical form of metal. Objectives differ in 
magnifying power, and are accordingly named 
“low power” and “high power.” Much care 
should be taken of all lenses, therefore hold them 
by the metal portions only. In looking through 
objectives the more pointed end should be near 
the object. How do objectives differ? To be of 
use an objective is screwed into the lower end of 
the tube, or accessory nose piece. 
C. To use the Microscope. 
1. With both sets of lenses in position place the micro- 
scope with the stage away from you. Arrange the 
mirror to obtain a bright circular area of white 
light (field of vision) as you look through the 
