comes to the mirror .or at right angles to the striae of 

 striated structures. The diaphragm d is operated by 

 the lever v. 



Use only plane mirror with the condenser. 



A condenser is so constructed that, parallel rays 

 of lighfr are brought to a focus above the upper surface 

 of its uppermost lens and in the plane of the object, 

 Fig. 52. If the concave mirror is used the convergence 

 of light is more rapid and the apex of the cone of light 

 is within the condenser, Fig. 53, and its effectiveness 

 depreciated. 



Fig. 52. Illuminating object with con- 

 denser and plane mirror. 

 The right way. 



Fig. 53. Illuminating object with 



condenser and concave mirror. 



The wrong way. 



Centering the Condenser is the act of bringing 

 its optical axis coincident with the optical axis of the 

 objective. 



In the simple forms of microscopes in which the 

 work is not critical, the condenser as sent out is 



