This is a horary quadrant engraved with Oughtred's horizontal projection, used to solve astronomical problems. The sights are intact but the plumb and bob are missing. The front of this quadrant appears to carry some scales similar to those on Willaim Leybourn's Panorganon but there are numerous differences. The 'line of hours' resembles that in Stirrup's discussion of a quadrant in his Horometria (1659) but there are no other similarities beyond this. It is not clear how this instrument would have been used, but it seems most likely that it was intended as a quadrant for dialling, as much as for telling the time itself. The reverse carries a horizontal projection of the sphere that can be used for demonstrating astronomical principles and solving various problems.

Fitted with sights.
On one side Oughtred's (1575-1660).
horizontal dial (a projection in which the plane is observer's horizon- invented sometime before 1618) for the solution of astronomical problems.