The effect of focal length and photo base on vertical exaggeration has been 
allowed for in the table on the Supplementary Slope Model. Other factors that affect 
vertical exaggeration are set up as constant factors and can be disregarded because 
they also affect the stereoscoplc target of the instrument. 
Radial displacement of relief inherent In the photography is compensated in 
large part by the displacement of the targets of the Stereo-slope comparator from a 
perspective point at the eye pleces of the stereoscope. 
Besldes determining angles of slope, this method provides a means of demon- 
strating the existence of vertical exaggeration and the factors that affect it. 
A complete evaluation of this Instrument Is In progress. At present the 
results are favorable.