PRACTICAL MICROSCOPY. 



enables one to alter the size of the opening at will. Below the stage 

 an arm may be seen which carries a fork supporting the mirror N. 



The whole is supported on a short, stout pillar rising from the 

 foot 0. 



FIG. 1. THE LABORATORY MICROSCOPE. 



This instrument was designed and constructed for the laboratories of the New York University 

 Medical College. It is strongly built; the mechanism is simple; and the height 10^ inches 

 not too great for use in the vertical position. 



LENSES OF THE MICROSCOPE. 



Fig. 2 shows the arrangement of lenses, including a high-power 

 objective of the Wenhain construction. 



The objective A is provided with one simple and two compound 

 lenses. The lens B, nearest the object, and the one upon which the 

 magnifying power mainly depends, is an hemisphere of crown glass. 

 Such a figured glass possesses both chromatic and spherical aberration 

 in high degree. These faults are corrected by the compound flint and 

 crown lenses, C and D, placed above the hemispherical glass. 



The eye-piece consists of two crown glass, plano-convex lenses, with 



