Octant or Hadley Quadrant

The Hadley quadrant was developed by John Hadley in England and by Thomas Godfrey in Philadelphia, both in 1732. The Hadley design took precedence and became the stock celestial navigation tool well into the 19th century, due to its simplicity and lower price than the more modern sextant. As most celestial navigation in the age of the Down Easter centered around sun sights and occasional lunar distances, there was not great need for owning a more expensive sextant.

The company that made this instrument was the highest volume producer of octants and sextants in the early 19th century. From 1780 to 1840 it traded as Spencer, Browning and Rust.