224 



SUMMAET OF CURRENT RESEARCHES RELATING TO 



A is the camera, BBB' are the prisms, C is the Microscope-tube with 

 objective and low-power eye-piece, D is the object-slide, and the dotted 

 lines show the path of the axial rays from the back of the objective. 

 The author considers that it is much better to divide the light, in this 

 manner, at the eye-point than to divide it, as is generally done, at the 

 back of the objective. If a lens of the focal length of the camera be 

 added as a cap for the eye-piece, the camera can be used without even 

 refocussing, in the fashion of the author's previous instrument. The 

 prism-box has a lateral fine adjustment by screw on the camera front,. 



Fig. 41. 



in order to readily set it, so that the apex of the small prism should 

 exactly bisect the circle of light at the eye-piece. The negatives pro- 

 duced in this camera are ready for printing from, no transposition of 

 images being necessary. Fig. 41 shows the stereoscopic camera used on 

 the adjustable base, as recently improved. The combination can be 

 adapted to the Microscope at any inclination and brought into action in 

 a few seconds ; and, after exposing, it is removed as a rigid whole by a 

 single rectilinear movement of one hand. 



New Upright Photomicrographic Apparatus.* — In designing his 

 apparatus J. A. Terras has studied the convenience of the operator. As 



* Proc. Scottish Micr. Soc, iii. (1002) pp. 210-2. 



