APPENDIX I 667 
The degree of angle of illumination directly affects resolving 
power up to a maximum resulting from filling the aperture of 
the objective with light. 
Fic. 496.—A modern monocular research microscope with revolving nose piece, 
side fine adjustment and substage. 
A 4 mm., 0.85 N.A. objective will resolve lines separated by 
distance ranging between 0.00062 and 0.00031, dependent upon 
the aperture employed. For a 4 mm., 0.65 N.A. objective the 
limiting values are 0.00081 and 0.000405. 
