for use with the periscope in high power.
When necessary to range on an object more
than 130 feet high, the stadimeter may be
used with the periscope in low power, and
the object set up on the height scale dial at
one-fourth its actual height. The range
reading is then correct."

The actual Stadimeter was installed with a "Course Angle Finder" as well as the Range Finder. What you did was, similar to the range finder, to adjust an image in length so it would fit with the actual image. Thus you could read out a Course Angle at the Stadimeter on the periscope....neet WE WANT THAT UBI