LENSES OF THE MICROSCOPE 



with their plane surfaces 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 



FIG. 2. DIAGRAM SHOWING THE RELATION OP 

 THE OBJECTIVE TO THE EYE-PIECE. 



constructed of various strengths depending upon the curvature of 

 the lenses. They are named according to power, A, B, C, or 1, 2, 

 and 3, or according to their focal distances. The medium power 

 is more commonly employed. 



The microscope previously described stands, with the draw- tube 



