Smithsonian - National Museum of American History, Behring Center

Physical Sciences Collection - Surveying and Geodesy

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Altitude and Azimuth Instrument - click to enlarge

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Altitude and Azimuth Instrument

Catalogue number:

"H. Morin 11, rue Dulong Paris" and "Aerostation Militaire No 215"

horizontal circle 6.25 inches diameter; vertical circle 5.5 inches diameter; telescope objective 1.5 inches aperture

This instrument and its mate would have been used, at either end of a base line, to observe air borne objects, primarily for military or meteorological purposes. The Signal Corps of the United States Army acquired the pair around the time of World War I, and transferred them to the Smithsonian in 1923. The beveled edge of the horizontal circle is graduated metrically to 400 grads, and read by opposite verniers to 1/20th of a degree. The vertical circle is graduated and read in the same way. A smaller telescope is mounted below the baseplate. The primary telescope is "broken," and thus the eyepiece remains at the same height regardless of the elevation of the objective. H. Morin began in business in Paris in 1880, making a variety of mathematical instruments. The firm was still in business in 1954.

Further Information:

Altitude and Azimuth Instrument