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Nikko Pilot Balloon Theodolite 

This theodolite model dates from World War II.  It is from Japan made in 1943.  It is similar in appearance and function to the British Watts Mark B of the 1930's

The Nikko has lighting a fixed focus telescope, dual azimuth and elevation readouts, and uses positively engaging tangent screws with a linked  engaging mechanism.  So both screws are engaged or disengaged with a linked switch. 

front side view of a Nikko Pilot Balloon Theodolite rear side view of a Nikko Pilot Balloon Theodolite

In the photo above right you can see the linked tangent screw engagement switch.  This model is very different in design and function from the Tamaya instrument of the same period.  Elevation, including the micrometer drum can be viewed from the rear of the instrument as well as the front, there are two azimuth circle windows as well, however the azimuth micrometer can only be viewed from the eyepiece side of the instrument.

Drive Type Tangent Screw Compass No
Display Type Micrometer to .1 degree
Levels 1,   bubble tube
Main Telescope 40 mm 20x Mounting Tribrach
Finder Telescope No Illumination 3, incandescent, scales
reticule
Gun Site Yes 1, main telescope Weight