dia eV ROSC@OPE 
AUGUST, 1897. 
NUMBER 56 NEW SERIES 
A Cheap Condensing Lens. 
Success in the use of the microscope depends largely 
upon proper management of the illumination. Some 
objects require a soft and subdued light ; others demand 
the most intense illumination that can be obtained, and 
the various ways in which the light ought to be modified 
so as to produce the best results, are more numerous than 
most persons are aware of. Among the numerous acces- 
sories used for purposes of illumination none are more 
useful, or will give better results, than the condensing 
lens or bull’s-eye condenser. And here let us explain 
the difference between these two: The bull’s-eye con- 
denser ought to be a hemisperical lens; a condensing 
lens may have any degree of curvature, 
