This navigation instrument features ivory scales, the largest divided for a range of 100 degrees with the cross-sectional scale of the arm divided from 0 to 20 minutes, on its ebony wood. The instrument is housed in an old but not original octant case. It measures 9 ¾ inches in width to its 11 ¾ inch overall length.

The ivory inlay is signed by the maker, J.F. Williams of 63 Broad Quay, Bristol.