110 LABORATORY EXERCISES. 



to the base and which carries upon its upper end the 

 joint provided for inclining the instrument. 



C. Arm. This supports all the upper parts of the 

 instrument. 



D.- Body. The tube portion to which are at- 

 tached the magnifying parts of the microscope. 



E. Nose-piece. This is an extra piece attached 

 to the lower part of the body, which provides a 

 means of quickly changing the objectives. 



F. Objectives. These are the most important 

 magnifying parts of the microscope. They are so 

 called because they are nearest the object that is 

 being examined. The shorter objective is called the 

 low power, because it magnifies least. The longer 

 objective is the high power. 



G. Eyepiece. It is so called because it is nearest 

 the eye. The eyepiece magnifies the image formed 

 by the objective. 



H. Draw-tube This is the portion of the body 

 which moves in the outer sheath and which receives 

 the eyepiece. If the tube is drawn upward the 

 magnifying power of the microscope is increased. 



1. Collar. A nng attached to the draw-tube. It 

 is usually provided with a milled edge. 



J. Coarse Adjustment. This is a provision for 

 moving the body of the microscope up and down by 

 means of a so-called rack and pinion. 



K. Milled Heads. The wheels on either side of 

 the coarse adjustment. When the wheels are turned 

 toward the observer the body carrying the magni- 

 fying parts is raised. 



L. Fine Adjustment. This horizontal wheel is at- 



