[Illustration: Figure 32.--Wooden graphometer used by Rev. Eleazar Wheelock (1711-1779) about 1769 for surveying the area of Dartmouth College in Hanover, New Hampshire. The hardwood block is covered with a brass plate with brass sighting bars mounted on a swivel and a spirit level under a brass strip on edge of instrument. The instrument is 8-5/8 in. long, 4-5/8 in. wide, and 7/16 in. thick. In collection of Dartmouth College Museum.] A list of the surviving wooden instruments is given in the Appendix (p. 153). Many of these wooden instruments bear signatures or other marks that permit identification of their makers, but a number of specimens have been found that are not signed. In most instances they show evidence of professional workmanship, and they may have been the work of known craftsmen. One or two examples are obviously homemade by unskilled amateur practitioners. [Illustration: Figure 33.--Wooden surveying instrument, maker not known. Compass dial is of metal, painted green, with degrees marked to 90 deg. 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.