SUB-STAGE ILLUMINATION. 



While the objective and its proper application and 

 use will always be the most important part of the 

 microscope, the proper illumination of objects is 

 second in importance. 



Mirror. As has been stated, the mirror alone 

 offers an excellent means of properly displaying an 

 object when intelligently used, for most of the low 

 and medium power objectives. On account of the 

 limited capacity of old objectives, efforts have been 

 made for the past fifty years to increase their utility 

 by the aid of lenses below the object. This was 

 mainly in the way of increase of intensity which at 

 the present day is not of so much consequence, as 

 our sources of illumination and light conveying 

 capacity of objectives is so much greater. 



Abbe Condenser. The history of sub-stage con- 

 densers is very unique and interesting, and shows 

 how from having been the subject of no end of con- 

 demnation it is now the reverse. From single lenses, 

 compound, non-achromatic and achromatic, the use 

 of eye-pieces and objectives with any number of 



