80 



PSYCHOLOGICAL EFFECTS OF ALCOHOL. 



Two views of the falling-plate recording-camera are shown in 

 figures 10 and 11. Figure 10 represents the back of the instrument, 

 showing the aperture for focusing, a plate-holder partly inserted, the 

 handle of the valve, and a stop for regulating the speed of the plate. 

 Figure 11 is a drawing of the inner construction of the camera. The 

 aperture for inserting the plate-holder when the box is closed is shown 

 at A. A shutter closing the recorder completely from the outside light 

 is shown at S. The oil cylinder to control the fall of the plate is indi- 

 cated at C. A plunger which is not represented plays in the cylinder. 



--PH 



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\ 



FIG. 10. FIG. 11. 



FIG. 10. Falling-plate recording-camera. 



FIG. 11. Falling-plate recording-camera (inner construction). 



It offers only slight resistance to raising the plate, but prevents its 

 falling, except when valve V is open. When the oil is forced out at 

 the bottom of the cylinder C it flows back through a by-pass B-PC 

 into the top of C. The speed of the fall is determined by the size of 

 the opening in the valve V. A commercial plate-holder open to expose 

 the plate is shown at PH. The focusing screen is shown at FG. It 

 is in the same plane as the photographic plate, and stands in front of 

 S until the plate begins to fall. The frame which holds the plate-holder 

 runs between two rails with V-shaped furrows. Oscillation of the 



