Fig. 1. 33:1. The location of the point of gravity as a function of the 
exposure time. 
Emulsion surface 
Fig. 1. 33:2. Radial displacement due to location of 
image. 
dr 
Fig. 1. 33:3. Radial displacement of points due to 
location in the emulsion (dr^) and due 
to variation in the exposure (dr^).