Figure 18.—Orrery by Joseph Pope completed in 1787 for Harvard University. Engraved plates and bronze figures were made by Paul Revere. The orrery is 6-1/2 ft. in diameter and 6-1/2 ft. high. The twelve figures at the corners are said to have been carved in wood by Simeon Skillin and cast in bronze by Paul Revere. Photo courtesy Harvard University.
It is believed that these calipers, which are preserved in the collection of the Bostonian Society in Boston, were probably used by Revere in 1775-1776. This was the period during which he was in charge of ordnance repairs for the Continental Army, and involved in various ventures for the manufacture of gunpowder and the casting of cannon. There is no evidence of other scientific instruments made by Revere, lending some weight to the belief that these calipers were made for his own use.
Figure 19.—Brass gunnery calipers made and probably used by Paul Revere (1735-1818). The calipers are 7 in. long and 1-3/4 in. wide.
Figure 20.—Reverse side of gunnery calipers, showing the inscribed signature. Photos courtesy the Bostonian Society, Boston, Mass.
Other Massachusetts instrument makers include Gideon Fairman (1774-1827) of Newburyport who was a partner of William Hooker in the firm of Hooker & Fairman, which dealt in mathematical instruments before 1810.[37] Fairman later moved to Philadelphia, where he was associated with the engraving firm of Draper, Murray & Fairman.
At the end of the 18th century Samuel Emery was making mathematical instruments in Salem, at the same time that John Jayne was engaged in the same work in that community.[38]