- The Pocket Altazimuth combines a sighting telescope with a magnetic compass for determining bearings, and a pendulum (or wheel) clinometer for determining vertical inclinations. Small, compact, and accurate, it was said to be especially useful for travelers and military surveys.
- L. Casella introduced the form in 1864, noting that is was "improved and modified by the kind assistance of Francis Galton, F.R.S." The reference is to Francis Galton, (1822-1911), a Fellow of the Royal Society of London, whose work ranged over a number of fields.
- The U. S. Geological Survey transferred this example to the Smithsonian in 1907. The This inscription reads "L. Casella Maker to the Admiralty & Ordnance LONDON 166."
- Ref: L. P. Casella, An Illustrated and Descriptive Catalogue of Surveying, Philosophical, Mathematical, Optical, Photographic, and Standard Meteorological Instruments (London, [about 1871]), p. 71.
(Cambridge, 1914-1930), vol. 2, p. 50.
- Currently not on view
- Object Name
- Pocket Alt-Azimuth
- Casella, Louis Paschal
- overall: 3 in x 5 1/2 in x 1 1/4 in; 7.62 cm x 13.97 cm x 3.175 cm
- overall: 2 7/8 in x 1 1/4 in x 5 1/2 in; 7.3025 cm x 3.175 cm x 13.97 cm
- ID Number
- catalog number
- accession number
- Credit Line
- U.S. Geological Survey
- Data Source
- National Museum of American History
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