SPECIAL MICROSCOPES 



265 



piece and looking through O c, it will generally be found that the 

 microscopical field is not evenly illuminated ; the light should then 

 be lowered or raised until perfectly uniform illumination is 

 obtained. 



The beam of light received by the lens, b, is made to converge, and 



Oc 



FIG. 207. Reichert's microscope for the examination of metals (1897). 



is reflected downwards, in the direction of the axis of the instrument, 

 by the glass-plate, a. It is then condensed upon the object by the 

 lenses of the objective itself. The illuminated object sends back a 

 portion of the light, which passes through the objective and the plate 

 ^, reaching the eye at O c. 



The object to be examined should have two parallel surfaces, so 



