1880.] 



MICROSCOPICAL JOURNAL. 



9 



purposes the stage is made of two 

 thin circular brass plates, the up- 

 per one, shown in the lower left- 

 hand corner of the engraving, fitted 

 to turn upon the lower, so that the 

 object can be rotated in 

 the field of view. The 

 stage can be centered. 

 The upper plate can be 

 removed, and two spring 

 clips attached to the 

 lower one, either above 

 or below, thus making 

 an excellent stage for use 

 with oblique light. 



The aperture in the 

 stage has a standard 

 screw-thread, which is 

 intended to receive va- 

 rious accessories for illu- 

 mination, when it is de- 

 sired to have the mirror 

 move independently of 

 them ; and also to afford 

 a means of mounting the 

 selenite, so that it can be 

 revolved without turn- 

 ing the Nichol prism. 



The mirror and sub- 

 stage are both attached, 

 by sliding fittings, to the 

 same bar, which carries 



them around the object as a center. 

 The circular piece at a right angle 

 to the stage, gives perfect steadiness 

 to the bar, and the movement is 

 very smooth ; this piece is gradua- 

 ted to show the angular di- 

 rection of the illuminating 

 pencil. 



The sub-stage is adapted 

 to carry the larger accesso- 

 ries — polariscope, parabo- 

 loid, etc., and is also pro- 

 vided with a cap having the 

 society -screw, so 

 that objectives 

 may be used as 

 condensers. It 

 has a centering 

 adjustment. 



The piece of 

 apparatus figured 

 in the cut, lying 



Fig. 3. — The New Acme Stand. 



immediately behind the stand, 

 screws into the sub-stage, and in its 

 upper part carries an admirably 

 constructed, adjustable diaphragm, 

 quite as good as the expensive iris- 

 diaphragm, of which it appears to 

 be a modification. 



The body-tube measures 1^^ 

 inches in diameter, and beside the 



society-screw, it is provided with 

 the new screw, of 1 finches thread, 

 for low-power lenses of extreme 

 angular aperture. 



The fine-adjustment moves the 

 entire body, and consists of an ad- 

 justable slide at the back part of 

 the arm, moved by a fine screw. 



The slides of both the quick and 



