Martin Brenner's, Pilot Balloon Resources 


Warren-Knight Model ML- 474-GM  Pibal Theodolite

This page contains photos and descriptions of the Warren-Knight ML-474-GM Pilot Balloon Theodolite.  The ML-474-GM is the Mil. Spec. Version of the Warren-Knight Model 20-8403 series of pilot balloon theodolite.  This series was formally produced by David White and some variants also by Seiler Instruments.  Currently these units are manufactured as 20-8403 and have a different color scheme and battery box.  See the Warren-Knight 8403 page for details.  Warren-Knight also produced a number of these in a black crinkle paint sceme.  

w-k474ft.jpg (19159 bytes) w-k474dis.jpg (32551 bytes)
In this front view you can see the battery box on the far left, main objective, finder objective and vertical circle tangent screw. In this view you can see the front bubble level, both tangent screws with micrometer drums, vertical circle and horizontal circle (under window), lighting rheostat and the finder scope  and switch switch.
w-k474sd.jpg (19281 bytes) w-k474bk.jpg (25606 bytes)
This is a similar view to the detail view above right showing the entire theodolite mounted on its tripod with lens shade and rubber eyepiece fitted.  In the rear view you can see the horizontal tangent screw micrometer, lighting switch, battery box, focus knob (only effects main objective), gun site and the compass (rectangular object with the red pointer)
Drive Type Positively Engaging Tangent Screw Compass Yes Fixed
Display Type Micrometer .1 degree Levels 2 plate,  bubble tube
Main Telescope 42 mm 21x 2deg. Mounting 4 screw leveling head, 3.5"x8tpi
Finder Telescope 17mm 4x 10deg.
single eyepiece
Illumination 3, 3 Volt lamps, scales
Gun Site Yes 1, 2 way foldable pair, main telescope Weight (theodolite only) 8.6 kg