CH. fill] 



PHO TO-MICROGRAPH Y 



237 



for observation should be used in photographing. Excellent results 

 have been obtained with them and also without them. 



Fig. 1S3. Zeiss' Apochromatic Projection Objective 

 oj yo mm. equivalent focus, for photo-micrography. 

 ( Zeiss' Catalog. ) 



is used for visual observation. 



Fig. 184. Gordon's Photo-Micrographic 



Apparatus. — In this apparatus there is placed 

 over the ocular of the microscope a tube contain- 

 ing a projection lens which focuses the image 

 on the sensitive plate just as the eye focuses the 

 image on the retina. A. The lube bearing 

 the plate at the top. It is about 150 mm. long . 

 B-C. Photographic plate about 40 mm. square, 

 contained in a cap (C) on top of the tube D. 

 Shutter for making the exposure; F. A flange 

 tilting the draw-tube and supporting the camera 

 (A); G. The microscope with a metal block 

 which may be clamped in position to prevent 

 the descent of the body of the microscope during 

 the exposure; E. A focusing ocular of high 

 power placed on the tube of the microscope to 

 ensure a perfect focus. If one has perfectly 

 normal eyes the focus with the ordinary ocular 

 gives a sharp image. 



With this apparatus the only change needed 

 in the -microscope is the addition of the camera 

 {A ) and the clamping of the metal block (G). 

 Then the exposure may be made. The use of a 

 color screen and properly sensitized plates apply 

 here as with any apparatus. " One of the chief 

 advantages of this extremely simple method of 

 photomicrography is that the performance of 

 the microscope is exactly the same as -when it 

 ' four. Roy. Micr. Soc, 1905, p. 651. 



