DESCRIPTION OF INSTRUMENT 
The Stereo-slope Comparator (flg. I) consists of two gear housings joined 
to a central block by sliding tubes. A shaft on which a target is mounted projects 
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Figure |. -- The Stereo-slope Comparator 
from each housing. Movement of the targets is synchronized by a gear arrangement . 
Control knobs on either housing and on the central block control the three motions 
of the synchronized targets. These motions are: 
a. Separation 
b. Horizontal swing 
c. Slope angle 
The separation motion is controlled by two knobs, A and B. (fig. I). Knob 
A, when loosened, permits rapid separation of the two gear housings. The amount of 
the separation can be increased or decreased. Knob A must be tightened after the 
approximate separation is obtained. Knob B controls a screw by which a finer adjust- 
ment of separation can be made. 
The horizontal swing motion of the shafts parallel to the base of the instru- 
ment is controlled from either housing by knob C or C'. By adjusting either of these 
knobs, the two shafts can be simultaneously swung to any desired position within an 
arc of 180°, By rotating the instrument 180° in reference to the viewing board or desk 
and by a similar adjustment of knob C or C', the shafts can be swung another 180°, 
completing a 360? arc of movement. 
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