This octant has a mahogany frame, flat brass index arm with ornate floral
pattern, and ivory name plate. The ivory scale is graduated every 20 minutes
from -5o to +95o and read by vernier to single minutes of
arc. There is also a back sight and a back horizon glass that could be used to
measure angles greater than 90o. J. Quincy was a mathematical
instrument maker in New York City in the 1780s. In the stepped wooden box is a
trade card of William Hooker, who operated a nautical shop in New York around
1820.
Ref: Deborah J. Warner, "American Octants and Sextants: The Early
Years," Rittenhouse 3 (1989): 86-112, on 107.
