Place the Stereo-slope Comparator over the Supplementary Slope Model 
(fig. 4), one target over the right image and one over the left. Adjust the 
separation, the horizontal swing, and the slope angle motions until the inclination 
of the targets (seen stereoscopically as one target) is in visual agreement with the 
  
Figure 4. -- The Stereo-slope Comparator oriented 
over the Supplementary Slope Model 
al a exaggerated angle of slope in the constructed stereoscopic model. This visual agreement 
can be made more accurate by adjusting the fine-thread separation knob B, which changes 
the separation of the targets in reference to the model and causes the stereoscopic target 
to appear raised or lowered In reference to the plane of the model (fig. 5a). By this 
adjustment the stereoscopic sloping target can be placed in, below, or above the plane 
of the selected slope in the model. The angle of slope is read in degrees on the instrument 
dial. Several readings should be taken to provide a good average, as this Is a critical 
measurement. 
b Y