Jonathan Sisson

[2] His apprentice John Dabney, junior, was an early instrument maker in the American colonies, who arrived in Boston in 1739.

[5][6] Sisson also employed John Bird, his co-worker under Graham, who became another leading supplier of instruments to the Royal Observatory.

[13] John Grundy, Sr. (c. 1696–1748), land surveyor and civil engineer, obtained a precision level with telescopic sights from Sisson before 1734.

[15][16] Sisson's theodolites have some similarity to earlier instruments such as that built by Leonard Digges, but in many ways are the same as modern devices.

There was no instrument in the Thirteen Colonies accurate enough to fix the location of the parallel precisely, so a request was forwarded to the Royal Society in London, and then to George Graham.

The 30 inches (760 mm) radius quadrant built by Sisson was found to be accurate within 1⁄120 of a degree, a very impressive level of accuracy.

The instrument proved reliable and easy to use in sea trials, even though weather conditions were poor, and was clearly an improvement over the cross-staff and backstaff.

[2] Joan Gideon Loten, an amateur scientist, owned an octant made by Sisson that he took with him on his assignment as Governor of the Dutch East Indian possession of Makassar (1744–1750).

He may have acquired it via Gerard Arnout Hasselaer, the regent of Amsterdam, who was in contact with Sisson and with his Amsterdam-based brother-in-law Benjamin Ayres, also an instrument maker.

[21] In 1785 the Royal Society heard a description of a brass standard scale made by Sisson under Graham's direction.

[2] One of Sisson's instruments was loaned by Pierre Lemonnier to the Berlin Academy, where it was used to supplement observations at the Cape of Good Hope by Nicolas Louis de Lacaille of the lunar parallax.

[24] Pope Benedict XIV arranged for astronomical instruments purchased from Jonathan Sisson to be installed in the Specola observatory of the Academy of Sciences of Bologna Institute.