C. L. Berger & Sons Transit

Description
This instrument is marked "C. L. Berger & Sons Boston, USA." The firm termed it a Universal Mining Transit with Duplex Telescope Bearings, noting that C. L. Berger had designed it on June 10, 1889, in order "to meet the requirements of the Mining Engineer, who must have the exact location of every shaft and tunnel in a mine" and who needed to get "the closest results under the most trying circumstances." It could measure horizontal angles between points, "one of which may be depressed as much as eighty or ninety degrees below the horizon, while the other may be as much elevated above the horizon; and also to measure with equal accuracy angles of elevation or depression above or below the horizon." The distinctive feature of this transit is that the telescope can be mounted in the center of the instrument, as usual, or, for extreme angles, it can be moved to the front of the instrument, with a counterweight attached to the back.
The Berger records indicate that C. Elliott of Pittsburgh ordered this instrument in February 1917. The horizontal and vertical circles are silvered, graduated to 30 minutes of arc, and read by opposite verniers to single minutes. With lamp, two tripods, and two plumb bobs, the instrument cost $620.
Ref: C. L. Berger & Sons, Hand-Book and Illustrated Catalogue of the Engineers' and Surveyors' Instruments of Precision (Boston, 1912), pp. 172-177.
Chicago Steel Tape-Berger Instruments (Document Management Systems, 1995), Book 36, p. 64.
Location
Currently not on view
Object Name
transit
date made
1917
maker
C.L. Berger and Sons
Measurements
overall: 12 1/2 in; 31.75 cm
horizontal circle: 5 in; 12.7 cm
vertical circle: 5 in; 12.7 cm
telescope: 9 in; 22.86 cm
striding level: 5 in; 12.7 cm
place made
United States: Massachusetts, Boston
ID Number
PH*334893
catalog number
334893
accession number
315134
See more items in
Medicine and Science: Physical Sciences
Measuring & Mapping
Surveying and Geodesy
Data Source
National Museum of American History, Kenneth E. Behring Center

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