122 



THE AMERICAN MONTHLY 



[June, 



glass plate. On the end of the metal support B is an arrangement, a, 

 by which the movement of a Hooke's joint b with rod b' can be trans- 

 ferred to the micrometer screw. This is effected by means of a toothed 

 wheel, which can be brought into gear with the toothed wheel of the 

 micrometer screw. The tube carries a double socket, /z, into which, by 

 turning the camera, slides a corresponding socket-piece attached to the 

 end of the camera, so that a very perfect light-proof connection between 

 microscope and camera is effected without disturbing the former. The 

 socket-piece can be easily removed and replaced by a macroscopic ob- 

 jective for ordinary photographic work. The camera K is mounted on 

 a separate light but solid cast-iron stand, SS, provided with iron rails 

 on which it can slide smoothly by means of rollers. The total length 

 of the camera when fully extended is one 1.5 m. 



In order to fit the apparatus for taking fluid preparations, the camera 

 is divided into two halves, of which the one nearest the microscope can 

 be turned up vertically, as in fig. 1 , or inclined at any angle. 



Fig. 1. — Zeiss' Photo-Micrographic Apparatus for Vertical Microscope. 



Movement of the plane of the image, and also of the microscope end 

 of the camera, is effected by pinions acting on a strong rack. Both 

 halves of the camera are arranged for plate-holders of 24 by 24 era. 

 which, however, by the addition of frames can be used for plates of any 

 smaller size. Two adjusting plates, one of ground glass and the other 

 transparent, and provided with a cross on the microscope side, serve 

 for the coarse and fine adjustment of the image. A third plate-holder 

 can be added, which, for the purpose of ascertaining the best time of 

 exposure, permits a great number of proofs to be taken one after an- 

 other on the same plate. To this end the holder is movable in a guide, 

 and is made to pass in front of a slit which allows only a small strip of 

 the image to fall on the sensitive plate. The bellows of the camera can 

 be drawn a little away from the plate-holder so as to permit the image 



