Ch. Ill] 



CARE OF THE EYES; WORK TABLE 



95 



The binocular microscope has certain advantages in that one uses 

 both eyes all the time as m naked-eye observation. If a binocular is 

 used, however, one must adjust it accurately so that each eye sees 

 an equally sharp image (§ 154). 



§ 161. In the beginning it is not advisable to look into the micro- 

 scope continuously for more than half an hour at a time. One never 



Fig. 57. Labokatory Table and Adjustable Stool. 



This table is 122 cm. long, 61 cm. wide, and 73 cm. high (2X4 feet on top, and 

 29 inches high). 



The corners and edges are rounded and the top is stained with aniline black. 

 The front of the rail is cut out, and the drawer is at the right so that it can be 

 opened without moving the stool. 



should work with the microscope after the eyes feel fatigued. After 

 one becomes accustomed to microscopic observation he can work for 

 several hours with the microscope without fatiguing the eyes. This 

 is due to the fact that the eyes become inured to labor like the other 

 organs of the body by judicious exercise. It is also due to the fact 

 that but very shght accommodation is required of the eyes, the eyes 



