194 



THE AMEKICAN MONTHLY 



[August, 



hold a slide, and yet allow easy movement about the field of view. 

 The substage has long sliding movements in the fixed bar be- 

 neath the stage, allowing ample room for a condenser or polarizer, 

 and exact adjustments are easily and quickly made by aid of milled 

 knobs extending on each side of the sliding bracket, on which the 

 ring of the substage is centered and affixed instantly by means of 

 a single set-screw with capstan head. The mirrors are plane and 



Zentmayer's American-Continental Microscope. 



concave, of large size, and have complete adjustments on an ex- 

 tensible bar. The diaphragms are cone-shaped, and have three 

 difterent sizes of apertures. The Abbe illuminating apparatus 

 has a condenser of i.30 N. A. and Iris diaphragm with complete 

 movements. A condenser of 1.40 N. A. can be substituted, if 

 preferred, for the diflerence in the cost of the condensing systems. 

 A set of stops are also furnished for dark -ground illumination. 



