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Physical Sciences Collection - Surveying and Geodesy

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Common Theodolite - click to enlarge

Common Theodolite - click to enlarge

Common Theodolite - click to enlarge

Common Theodolite - click to enlarge

Common Theodolite - click to enlarge

Common Theodolite - click to enlarge

Click photos to enlarge.

Common Theodolite

Catalogue number:
1985.0860.01

Inscriptions:
"ROWLAND HOUGHTON Fecit"

Dimensions:
alidade 11.5 inches long; needle 5.125 inches

Discussion:
This is an example of the "new theodolite" for which Rowland Houghton (about 1678-1744), a Boston mechanic, received a patent from the General Court of the Colony of Massachusetts in 1735. This was the second patent for a mechanical invention issued in the British colonies of North America. The patent did not describe Houghton's instrument, but stated simply that it was designed "for surveying of lands, with suitable instruments, with greater ease and dispatch than any surveying instrument heretofore projected or made within this province." The only other contemporary reference to this instrument appears in Houghton's 1737 advertisement for aqueducts, which states that "Said Houghton has lately improv'd on his new Theodolate (sic), by which the art of Surveying is rendered more plain & easy than heretofore."

The horizontal circle of Houghton's instrument is graduated to degrees, and numbered in quadrants. One side is also numbered from VI to XII to VI, as for a sundial. The sights vanes for the alidade are missing. The compass card--marked "J. R. LINCOLN, BOSTON"--is a 19th-century replacement.

When the Smithsonian acquired this instrument, it was the only known surviving example. Another example, however, has recently come to light.

Ref: Silvio Bedini, "Rowland Houghton's 'New Theodolate,'" Rittenhouse 1 (1987): 30-39.

Raymond V. Giordano, "Some Notes on the Two Extant Rowland Houghton New Theodolates," Rittenhouse 15 (2001): 93-97.

Further Information:

Theodolite

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