LENSES OF THE MICROSCOPE. 



their plane surface upward. The lower, E, is known as the field-lens, 

 the upper, F, as the eye-lens. Eye-pieces add very materially to the 

 magnifying power of the instrument, and are constructed of various 

 strengths depending upon the curvature of the lenses. They ar& 



FIG. 2. DIAGRAM SHOWING THE RELATION OF THE OBJECTIVE TO THE EYE-PIECE. 



named according to power, A, B, C, etc. The medium, B, is more 

 commonly employed. 



The microscope previously described stands, with the draw-tube 

 in place, about ten and one-half inches high; and represents the in- 



