Written by William Alexander at Basking Ridge, New Jersey, March 27, 1773, this essay appeals to the American Philosophical Society to collect and publish astronomical observations. It was sent to the American Philosophical Society, where it was duly read in May 1773.

Marked "Potts and Rittenhouse." 6" compass set in 13 3/4" sighting arm with sights 6 1/4" high. On walnut tripod. (Robert P. Multhauf, "Catalogue of Instruments and Models," 1961).

Incomplete theodolite. Two fixed sight vanes are mounted to the horizontal circle, which is attached to the tripod assembly through the socket. Rotating compass and alidade with vernier blades in center. Signed "B. Chandlee Nottingham" along outer circle. Analysis of the alidade by a Scanning Electron Microscope in 2007 revealed that it contained silicon, most likely originating from a mixture of silicon bronze, a product that was not developed until the late 19th to early 20th century. Therefore, the alidade is not original to the piece.

Brass compass with a variation arc on the north arm, and a level vial on the south arm. Signed "T. Whitney / Maker / Philadelphia" on compass face. The instrument is dated "1814" under socket. It is in its original condition, with the exception of the Jacob's Staff attachment screw, which was added at a later date.

Mahogany block with inset compass and cover. Possibly contemporary inked inscription, "Belonging to the globes presented by W. & S. Jones, 18 April 1800." (Robert P. Multhauf, "Catalogue of Instruments and Models," 1961).