Figure 1-7.ML-474 shore telescopic theodolite with an ML-1309 tripod.
desk-top computers available through the Geophysics
Fleet Mission Program Library (GFMPL).
The theodolite is used to obtain the azimuth and
elevation angles of the balloon. These angles are read to
the nearest one-tenth of a degree. For use at night, a
battery-powered lighting circuit illuminates both the
azimuth and elevation scale. The theodolite telescope
has an adjustable focus and must be refocused several
times during the course of an observation. It also has a
low-power setting for use early in the sounding, and a
high-power setting for use when the balloon attains
higher altitudes, The theodolite must be mounted on the
tripod, leveled, and oriented to true north before use.
Detailed guidance on the proper use, care, and storage
of the theodolite is contained in the FMH-3 and AN 50-
30WH-1, Handbook of Overhaul Instructions with
Parts Catalog for Theodolite AERO-1928-USN and
Tripod AERO-1930-USN, and Signal Corps Theodolite
ML-474 and Tripod ML-1309.