Figure 67.—Wooden surveying compass made by Thomas Salter Bowles of Portsmouth, New Hampshire. With spirit level. Made of birch, the compass is 13 in. long and has a diameter of 6 in. In the Streeter Collection of Weights and Measures, Yale University.
The most interesting of the three instruments was acquired by the Dartmouth Museum as part of a collection of the late Frank C. Churchill, an inspector in the Indian Service. The instrument (fig. 69) is a quarter circle with a compass in its center and sighting bars mounted on a swinging arm that reads the angle of the brass scale on the arc by means of a vernier. It is mounted on a wooden tripod with the customary ball-and-socket joint, which permits it to be placed on a vertical plane. A built-in plumb bob at the side helps to establish the vertical.[127]
Interesting features of this instrument are two inscriptions engraved on the brass strip on the top of the dial. One states that it was "INVENTED BY P. MERRILL ESQ." and the other relates that it was "MADE BY JOHN KENNARD NEWMARKET." No information about P. Merrill has been found, and it is presumed that it was he who conceived the idea of combining the various elements into a single instrument and that it was made under his direction by Kennard.
Figure 68.—Wooden surveying compass made by Thomas Salter Bowles (1765/70-post 1821) of Portsmouth, New Hampshire. Made of walnut, it is 12 in. long and has a diameter of 5-3/8 in. With walnut sighting bars. In collection of writer.
