FUNDAMENTAL CONSIDERATIONS 
5 
Draw-tube 
Horse-shoe base 
Fig. i. — I llustrating the parts of a compound microscope. 
5. The diaphragm, inserted in the opening of the stage or attached 
to its lower face, and used to regulate the amount of light reflected 
by the mirror. 
Ocular 
Prism washer 
Inclination joint 
Pillar 
Body tube 
Nosepiece 
Rack and 
pinion coarse 
adjustment 
Micrometer head 
of fine adjustment 
Arm 
Fine adjustment 
pillar 
Clips 
Objectives] 
Stage ' 
Upper iris diaphragm 
substage ring 
Condenser mounting 
lower iris diaphragm 
Condenser focusing screw 
Mirror — 
Mirror fork 
Mirror bar 
6. The body tube, a cylinder which holds the draw tube and lenses 
and moves up and down perpendicularly above the opening in the 
stage. The tube is raised or lowered either by sliding it back and 
forth with a twisting movement or by a rack and pinion mechanism. 
The latter is called the coarse adjustment. 
