12 LABORATORY METHODS AND EQUIPMENT 



B. To set the microscope up : 



1. Lift it out of its case by the lower part of the column to 

 which the stage is attached, never by the tube or where the 

 fine adjustment operates. 



2. Place it on the table with the fine adjustment nearest you. 



3. Screw the objectives into the nose piece and slip an 

 ocular into the upper end ; turn the lowest power objec- 

 tive into position. 



4. Find the light by looking into the eyepiece and at the 

 same time turning the mirror at such an angle that it 

 reflects light from the window up through the opening in 

 the stage to the objective. When a clear, bright field is 

 obtained the microscope is set up. 



5. Regulate the quantity of the light by the diaphragm. If 

 too bright it must be cut ofE somewhat. The higher powers 

 require brighter light than the lower. Mirrors generally 

 have two faces, a plane and a concave. The concave mirror 

 is used with the high-power objectives. 



C. To find the object: 



1. Place the slide on the stage, which should always be 

 horizontal, with the object over the middle of the opening 

 through which light is thrown from the mirror. 



2. With the lower power in position move the coarse ad- 

 justment until either the object or small solid particles 

 on the slide appear distinctly, which means that the lenses 

 are in focus. The object, if not under the lens, may now be 

 brought into the field by moving the slide back and forth 

 very slowly. The focus of the coarse adjustment may gen- 

 erally be improved upon by the fine adjustment. 



■3. To focus with the high-power objective, first find the 

 object with the low power and arrange in the center of the 

 field. Then turn the high-power objective into position. In 

 well-made instruments it will generally be found to come 

 nearly into focus, and a slight movement of the fine adjust- 

 ment will show the object clearly. If not in focus, move 



