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Buff & Buff Balloon Theodolite c. 1918 Type ML-47
The Buff & Buff theodolite was the mainstay of U.S. Meteorological Observations until the adoption of the David White/Warren-Knight Series in the 1940's. The theodolite illustrated here is a vernier type and is seen in publications dating from the 1920's (military and civilian.) This illustration is taken from "United States Army, Training Manual No. 31, Meteorological Observers, Instructor's Guide For All Arms, 1925. The theodolite is listed as "special aircraft, type ML-47".
An interesting fact about this device is that it is broken down into three pieces for storage. The vertical circle, prism and telescope assembly is removed from the standards, and the base is stored, then the eyepiece, and right angle tube including the focusing screw is removed and stored. The three parts are reassembled for use.
An example of this theodolite is in the collection of the Smithsonian Institution National Museum of American History use this link. Information on the museum's page notes the instruments appearance in a 1918 Buff & Buff catalog.
A recording version of this instrument was shown in the catalog and the simpler version is referred to but not shown. Thanks to Deborah J. Warner, one of the museum curators for writing me about the museum's collection and providing Buff and Buff catalog information.