The quadrant, an instrument used to calculate various readings, such as longitude, latitude, and time of day was a forerunner of the sextant. Madison native John Wilcox used this quadrant to measured the altitude of heavenly bodies for navigation on his voyages from Madison to New York and along the Connecticut River in the early 1800s to about 1860.

The brass and ebony instrument features the maker’s name and compass degrees engraved on ivory set into the frame. It also has colored glass filters used in the sighting device. The quadrant is housed in an oak box with partial label of William Davenport an instrument dealer in Philadelphia. The side of the box is painted yellow and has faint traces of a star and “JOHN WILCOX” painted on it. Made by Spencer, Browning & Rust, London England c. 1800.