PRACTICAL PHOTO-MICROGRAPHY 



137 



stopping down of the projection lens which will entail greatly 

 prolonged exposure. The usual " motions " of the large camera 

 "rise and fall" and "traverse" of the front, will enable us to 

 arrange our image on the ground-glass ; while the small camera 

 carrying the negative will by its rack and pinion enable us to 

 arrange the magnification. The focusing of course is done on 

 the ground-glass, and with the rack and pinion of the large 



FIG. 33. 



camera. The small camera's back is pointed towards the light, 

 and an angled reflector, or ground-glass "diffuser" is used as 

 before. With this arrangement there may be a difficulty in 

 focusing due to want of light ; in this case plain glass may be 

 substituted for ground-glass, and the focusing done with an 

 eye-piece of the Ramsden, or " Zeiss Aplanat " type. 



