Engraved in script on the silvered compass face, "Heisely & Son Harrisburg". Circa 1811-1843. Charles Smart, in "The Makers of Surveying Instruments in America Since 1700", documents the Heisely family during their three generations as makers. Frederick Heisely, the senior, born 1759, enlisted in Captain Jos. Howell's Company, 2nd PA regiment, in 1778. George, the son, was in Green's Company of the Maryland Militia and then the Harrisburg Volunteers, Captain Walker's Company, active during the war of 1812. This "Heisely & Son" signature dates from 1811 to 1843. The instrument measures 14 inches in length and carries both two sight vanes, and an auxiliary telescope. The compass face has a read-out for the magnetic variation, and one long bubble vial with original blue interior. There is another bubble level outboard of the compass on the mainplate. On the side of the compass is a graduated vertical arc and vernier, this was used to record vertical angles, which while slope chaining, reduced to horizontal distance by trigonometric functions. The original compass cover, ball and socket, tripod, plumb bob, measuring chain and tacked leather covered case accompany the instrument.

Very good, with a mottled brown field patina throughout. One of the two telescope thumb screws is a replacement. The tripod is in good condition, note scuffs and field wear to the surface of the wood. The leather in the case is dry and worn.