R & A Rost (after Dr. Kölzer-Sprenger) Balloon Theodolite,
Vienna
This theodolite model was acquired from the Rudolf & August Rost company of Vienna Austria. It was manufactured in 1949. The theodolite is a more recent version of the Kölzer-Sprenger balloon theodolite that was manufactured in Berlin Germany in the 1930's. Even the crates look the same. See Dr. Hegar's page on the German instrument for details. These instruments are refinements of the original Bosch and Bosch instruments that date to back to 1905. The Gerlach (Warsaw Poland) instrument is an earlier variant in this instruments lineage.
The Rost balloon theodolite can be read from the front or back, it has a large range of adjustable focus, lighting and no finder scope. It is about the same size as the Warren Knight instruments. The large rectangular box with the cable attached is the battery box. It has a rotating switch on the back. In the comparison photo below you can see the reticule lamp switch located near the vertical circle on the eyepiece tube.
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| Drive Type | Positively Engaging Tangent Screw | Compass | No |
| Display Type | vernier .1 degree | Levels | 2 plate, bubble tube |
| Main Telescope | 40 mm 7.5x 2.5deg. | Mounting | 3 screw leveling head, |
| Finder
Telescope (on some units, other lack this) |
NO | Illumination | 2,
lamps, scales reticule |
| Gun Site | Yes | Weight (theodolite only) | approx 8.6 kg |