Surveyor's Transit


This is marked "J. C. SALA MAKER SAN FRANCISCO 825." Sala termed it an Engineer's Complete Transit, and priced it at $235. The horizontal circle is silvered, graduated into 64 units (each equal to 100 mils), and read by opposite verniers to 30 parts. One mil (or military degree) equals 3.375 arc minutes. A variation arc, outside the compass at E, extends 30 degrees either way; the vernier reads to single minutes. The vertical arc, also silvered, is graduated into 30 minutes of arc, and read by vernier to single minutes. There is a clamp and tangent attachment to the telescope axis, as well as a gradienter attachment for determining gradients, distances, and differences of level.

Joseph Charles Sala (1841-1916) was born in Italy, moved to San Francisco around 1861, and worked for John Roach. Following Roach's death in 1891, Sala went into business for himself, advertising as "Successor to John Roach" and noting his many awards from the Mechanics' Institute of San Francisco.

Ref: J. C. Sala, Illustrated Catalogue and Manual of Civil Engineers' and Surveyors' Instruments (San Francisco, 1896).

Date Made: 1891-1916

Maker: Sala, Joseph Charles

Location: Currently not on view

Place Made: United States: California, San Francisco

Subject: Italian Americans


See more items in: Medicine and Science: Physical Sciences, Surveying and Geodesy, Measuring & Mapping


Exhibition Location:

Related Publication: Sala, J. C.. Illustrated Catalogue and Manual of Civil Engineers' and Surveyors' Instruments

Data Source: National Museum of American History

Id Number: 1985.0599.01Accession Number: 1985.0599Catalog Number: 1985.0599.01

Object Name: surveyor's transit

Measurements: overall: 10 1/2 in; 26.67 cmhorizontal circle: 6 in; 15.24 cmneedle: 4 1/4 in; 10.795 cmtelescope: 10 1/2 in; 26.67 cmhanging level: 5 in; 12.7 cmoverall: 13 7/8 in x 6 7/8 in x 10 1/2 in; 35.2425 cm x 17.4625 cm x 26.67 cm


Record Id: nmah_745978

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