12 
PHARMACEUTICAL BOTANY 
the objective is called an oil immersion objective; if water, a water 
immersion objective. 
Some microscopes are fitted up with a nose piece , capable of carry¬ 
ing two or three objectives, which may be revolved into place at the 
Fig. 5. Fig. 6. 
Fig. 5.—Microscope lamp useful in illuminating opaque objects. 
Fig. 6'.—Compound microscope with binocular body, designed to relieve 
eyestrain for those spending many hours with the microscope. Each oculai 
inclines at an angle of 4 degrees from the perpendicular, which results in their 
converging to a point about 17 inches from eyes having the average pupillary 
separation. Adjustment for pupillary distance is accomplished by turning 
a knurled ring on the right hand ocular tube which gives a horizontal sliding 
movement of the oculars. The knurled ring on the left hand ocular tube pro¬ 
vides a means of focusing one eyepiece independently of the other. (Made by 
Spencer Lens Co.) 
lower end of the body tube. Others have a condenser which is 
employed to concentrate the light upon the object examined. 
B. Its use: 
1. Place the microscope on the table with the pillar nearest you. 
2. Screw the objectives into the nose piece and slip an ocular into 
the upper end, if not already on instrument. Turn the lowest power 
objective into position. 
