Figure 33.—Wooden surveying instrument, maker not known. Compass dial is of metal, painted green, with degrees marked to 90° with metal punches and the letter "N" to designate the north point. The instrument is 12 in. long; diameter is 8 in. In collection of Dartmouth College Museum.
Several unsigned wooden instruments of professional quality are in the collection of the Dartmouth College Museum. Of particular interest is a semicircumferentor (fig. 32) that belonged to the Reverend Eleazar Wheelock (1711-1779) who founded Moor's Indian Charity School at Lebanon, Connecticut, which subsequently developed into Dartmouth College. It is claimed that it was with this instrument that the area of the college was surveyed when it moved to Hanover, N.H. The instrument is actually a graphometer consisting of a block of hard wood faced with a brass plate with a trough compass; it is tentatively dated about 1769. The identity of the maker is unknown, but it may have been the product of Hagger, who made a similar instrument, illustrated here, or it may have been produced by any one of the other makers noted. The type of instrument is an old one. It is described in John Love's Geodaesia, Or the Art of Surveying and Measuring Land, published in London in 1688. Abel Flint[78] also commented on this semicircle as being sometime used, as well as the plane table and perambulator—
... but of these instruments very little [use] is made in New England; and they are not often to be met with. For general practice none will be found more useful than a common chain and a compass upon Rittenhouse's construction.
Another of the unusual wooden surveying instruments in the collection of the Dartmouth College Museum is a wooden surveying compass (fig. 33) in which the sighting bars appear relatively close to the dial. A metal plate, painted green, is stamped with the degrees marked to 90°. A single N for the north point is stamped into it, presumably with steel punches. The instrument is relatively primitive, and is sufficiently different from the other examples noted to merit mention. There is no maker's name, nor any clue to the date or place or period of origin.
An unsigned semicircumferentor made of wood is owned by Mr. Roleigh Lee Stubbs of Charleston, West Virginia. The instrument measures 3-3/4 in. by 7-1/2 in. by 1 in., and there are sighting bars 3 in. high on a swinging brass bar pinned at the center of the base. It has a trough compass, and the gradations around the edge of the semicircle are marked with tiny brass pins. The date "1784" is stamped into the wood with the same type of figures as appear in the degree markings, probably with small steel punches.
A surveying compass of the conventional type, also made of wood, is in The Farmer's Museum at Cooperstown, New York. The wood is ash or oak, 12-3/4 in. long and 6-1/2 in. in diameter, with the sighting bars 5 in. high. The compass card consists of cut-out printed letters pasted upon a printed compass rose, and the fleur-de-lis at North is inked-in by hand. This may be a homemade replacement of the original card. The instrument is believed to date between 1760-1775.
Figure 34.—18th-century semicircumferentor. Inscribed brass plate is mounted on a mahogany block; brass sighting bars are mounted on a swivelling bar. The trough compass is on a silvered dial. In collection of the writer.
Of equal interest is a large semicircumferentor made by an unknown American instrument maker in the second half of the 18th century. The instrument (fig. 34) consists of a plate of hammered brass attached to a quarter circle block of mahogany, with a glass covered trough compass within a silvered opening, and the gradations stamped into the brass. The brass sighting bars are attached to a swivelling bar that can be fixed in place with a set screw underneath the block. The instrument, which is in the collection of the writer, is not signed with a maker's name. Its workmanship is excellent, and professional.