CH. VIII.'] 



/'IIO TO-MICROGRAril I ' 



207 



Fig. 162. 



Arrangement of a vertical or horizontal camera for making photographs of nat- 

 ural history objects — sectional view. 



1. The photographic objective. It should be of the best quality and rectilinear 

 so that there may be no distortion. 



2. Cone to increase the length of the camera and avoid shadows. 



3. Graduated rod to support the front of the camera and hold it rigid, and also 

 to serve as guide to the various magnifications and reductions most commonly 

 desired. 



4. Ground glass. It is an advantage to have a clear space in the middle for 

 accurate focusing, as for the photo-micrographic camera {Fig. 153). 



5. Camera bed fastened to the sliding focusing board, 6. 



6. Focusing board to zvhich the camera is clamped. 



7. Focusing screw. 



S. Solid piece connecting the focusing board and focusing screw, 



g. Hinge on which the camera swings. 



10. Drawer in which are kept the objective and other accessories. 



11. Box of sand or other heavy material to serve as ballast. 



The large screw eyes in the legs of the table serve as leveling screws. 



4 . If the photographic prints are to be used solely for outlines, the 

 well-known blue prints so much used in engineering and architecture 



