114 PKACTICAL PHOTO-MICROGRAPHY 



but its use requires more than ordinary care, owing to the 

 fact that in inserting the dark -slide, or in withdrawing the 

 shutter of the latter, there is considerable liability of altering 

 the focus of the microscope. 



A type of vertical camera which admits of rather wider 

 application is that made by Zeiss, Leitz, and others, in which 



FIG. 38 a. Combined Horizontal and Vertical Camera. (E. Leitz.) 



the camera is supported separately from the microscope (Fig. 

 37). The arrangement is generally one in which a stiff steel 

 rod is supported on a tripod foot ; the camera, both at the lower 

 end near the microscope and also at the frame which carries 

 the focussing-screen, is fixed by clamps to the rod and is 

 capable of adjustment in a vertical direction. The microscope 

 stands on the table as before, so that there is no rigid connection 

 between the microscope and the camera. This type is a very 

 convenient one, since the camera can be bodily removed, or can 

 be swung round on the supporting-rod when observations have to 



