22 



INTRODUCTION. 

 FIG. 1. 



G 



Microscope : A, ocular or eye-piece ; B, objective system ; c, stage ; D, iris 

 diaphragm (its opening may be diminished or increased by means of a small lever) ; 

 E, mirror or reflector; F, coarse adjustment; G, fine adjustment; H, substage con- 

 denser (Abbe's) ; i, nose-piece. 



from the centre of the lens," the less the equivalent focal 

 distance of the objective, the greater is its magnifying power. 



