Note:  Do not rely on this information. It is very old.

Hadleys Quadrant

Hadley's Quadrant, or the Reflecting Quadrant, was introduced by John Hadley in 1731 to take the place of the backstaff, or Davis's quadrant. It was formerly used for taking the altitudes of the sun and stars, and for taking angles in surveying. Its form was that of an octagonal sector of a circle. The arc, therefore, contained 45°, but, there being double reflection, the limb was divided into 90°. The quadrant is now superseded by the sextant.

“What a blessed condition is a true believer in! When he dies, he goes to God; and while he lives, everything shall do him good. Affliction is for his good. What hurt does the fire to the gold? It only purifies it.”
–Thomas Watson, A Divine Cordial