Fig. 1S4. — Vertical photo- 

 micrographic camera , screen and 

 small table. The table is about 

 45 centimeters high and in the 

 legs are large screw eyes for 

 leveling screws. The operator 

 can stand on the floor and per- 

 form all the necessary opera- 

 tions, and in adjusting the mi- 

 croscope can sit on a low stool. 



The screen is of zinc and 

 has two heavy lead feet to hold 

 it steady. Near the lower left 

 hand corner of the screen is an 

 aperture for the light to shine 

 through upon the mirror. This 

 opening is closed by a black slide 

 which is just balanced so that it 

 stays in any position. In mak- 

 ing the exposure il is raised 

 sufficiently to admit the light to 

 the mirror, but the stage is left 

 in shadow. 'This screen shades 

 the microscope and the face of 

 the operator. ( Trans. Amer. 

 Micr. Soc. /go/. ) 



