+he basis of lake surfaces or stream gradients, can be used for plotting 
profiles of areas where no vertical control is available. The following 
is a suggested procedure for construction of vertically enlarged profiles: 
a. Determine line of profile in the stereoscopic model, draw 
line of profile on base map, and set up the plotting board. 
b. Set the desired ratio of enlargement on the profile plotter. 
c. Insert the track bearings into the metal track of the plotting 
board and release the pencil. Draw the profile by moving the 
tracing table across the stereoscopic model, keeping the 
lighted reference mark of the tracing table on the apparent 
ground surface. 
d. Retract the plotting pencil and inspect the model along the 
line of section. Mark geological and cultural features to be 
included in the section by releasing the pencil at the correct 
profile position of each feature. 
e. Select reference line of known elevation and draw it on the 
profile. Mark scale of model and enlargement ratio on profile. 
To date the instrument has been used in stratigraphic and structural 
study, but it can be used in many other studies that require detailed 
ground profiles. 
Some of the advantages of using the instrument are as follows: 
The instrument can be used with any of the double-projection stereo- 
scopic plotting instruments. Enlargement ratios are easy to change 
and two or even three profiles of different enlargement ratios can be 
drawn quickly. Several detailed vertically exaggerated profiles can