Zenith Telescope
name: label: maker
content: Troughton and Simms
notes: label: Description
content: Marked "Troughton & Simms, London" and "U. S. C. S. Z. T. No 3," this is one of four zenith telescopes that Troughton & Simms made for the U. S. Coast Survey. It was used for determining latitude by the Talcott method.
label: Description
content: The telescope arrived in the United States in 1848. In 1891, in preparation for the variation of latitude (polar motion) program organized by the International Geodetic Association, this telescope was extensively remodeled. The new features included: an objective lens made by Brashear; diagonal and straight eyepieces made by Kahler; two levels; a striding level; a micrometer with horizontal and vertical parallactic motions; a larger axis for the telescope; a heavier base and vertical axis; wyes to support the telescope; and an improved clamp for the telescope.
label: Description
content: Ref: C. A. Schott, "The Variation of Latitude at San Francisco, Cal., as determined from Observations made by George Davidson, Assistant Coast and Geodetic Survey, Between May, 1891, and August, 1892," <i>United States Coast and Geodetic Survey Report for 1893</i>, Appendix No. 11, p. 449.
label: Location
content: Currently not on view
place: label: place made
content: United Kingdom: England, London
setName: label: See more items in
content: Medicine and Science: Physical Sciences
label: See more items in
content: Surveying and Geodesy
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content: Measuring & Mapping
publisher: label: Related Publication
content: United States Coast and Geodetic Survey Report for 1893
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: PH.314636
label: accession number
content: 208213
label: catalog number
content: 314636
objectType: label: Object Name
content: zenith telescope
physicalDescription: label: Measurements
content: telescope aperture: 3 1/4 in; 8.255 cm
label: Measurements
content: telescope: 46 in; 116.84 cm
label: Measurements
content: horizontal circle: 10 1/2 in; 26.67 cm