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 lelt 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 micrqscope 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. 



