The signature refers to Charles Gedney King (1808-1858), a mathematical instrument maker in Boston who apprenticed with his father, Gedney King, and traded under his own name after his father’s death in 1839. C. G. King showed his instruments at several fairs sponsored by the Massachusetts Charitable
Mechanics Association in the 1840s and 1850s, and took home several silver medals. He also boasted that he "Is now manufacturing and has for sale the largest assortment of Mathematical, Nautical, Engineers, Surveyors and Drafting Instruments to be found in the city." Moreover, the engineers’ and surveyors’ instruments manufactured in the King Establishment, "are divided upon a new Engine, made expressly for the purpose, the performance of which, for the accuracy of its division, cannot be surpasses, if equalled, by any Engine in the Country."
The rim of this compass is graduated to 30 minutes. There are two level vials on the south arm.
Ref: "Evidence of the Enterprise," Rittenhouse 1 (1987): 90.