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
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.