Rare Colonial Brass Theodolite

Rare Colonial Brass Theodolite, with 5 1/2-inch diameter unengraved silvered dial, steel needle with pierced N and S directionals, cross-strut with bezel and wingnut holding a rotating brass horizontal circle with punched scale 0-90 through four quadrants, a filled guide-hole at the two 0 points and two corresponding holes on either side of the bezel, the alidade with read-outs and finely-cut folding sights with twin clamps, with the upper-half of the staff adaptor and possibly later ball, lg. with sights 10 in. , sights 4 1/2 in., (replacement wingnuts on alidade). Note: Probably a contemporary copy of Rowland Houghton's "New Theodolate", the first patented Amerian surveying instrument. Houghton (c.1678-1744), of Boston, patented his instrument - a combined theodolite and circumferentor - in 1735. Other contemporary copies of Houghton's theodolite are known, including a four-vaned version with two folding sights, by Thomas Greenough. The instrument offered here has a more provincial appearance, with the needle ring punched instead of engraved, although it has several aspects in common with both the original and the Greenough copy. Literature: Raymond V. Giordano, Rittenhouse , Vol. 15, No. 2, pp. 93 - 97. Jeffrey Lock, The American Surveyor , May / June 2004, pp. 36 - 40.