This navigation instrument features bone scales, the largest divided for a range of 100 degrees with the cross-sectional scale of the arm divided from 0 to 20 minutes. The instrument is housed in its original period octant case. It measures 9 1/2 Inches in width to its 12 inch overall length. Case size is 11 7/8 wide by 13 high by 4 3/8 deep.

The inlay is signed by the maker, G. Heath of London, while the box includes a label for Samuel Thaxter and Sons, Boston, Importers of Mathematical and Nautical Instruments, who were the likely retailers of this object to its original 19th century owner.