59 School Street, Box 1310, Edgartown MA 02539 - 508.627.4441
Martha's Vineyard Museum MV Museum



Benjamin King (1707–1786)

Newport, Rhode Island

Wood, ivory

Gift of Julia Dunham

Sea captains, mates, and pilots traveled the vast oceans, sometime spending weeks without seeing a single landmark. To stay on course, they required specialized navigational tools and charts such as this backstaff, also called a Davis quadrant.

Surviving notebooks that belonged to navigators record formulas for calculating the azimuth, amplitude, declination, and other measurements relating to celestial bodies. The formulas were used in combination with tools like the backstaff to determine latitude at sea based on the position of the sun relative to the horizon. This backstaff, though it has lost two pieces that would have marked positions along each of its arcs, is a fine New England–made piece of equipment.

A prosperous sea captain would have sought out well-made and handsome instruments like the ones made by Benjamin King of Newport, Rhode Island. He made this backstaff for Captain Benjamin Allon (or more probably Allen; spelling was not standardized in the mid-1700s). It is one of the earliest examples King is known to have made.

The Allen and Dunham families settled on Martha's Vineyard in the 1600s. This backstaff almost certainly descended through the Dunham family, but the details of Captain Benjamin Allon's life remain frustratingly obscure.

With thanks to the following individuals who have adopted this object for one year: Fenton and Margarett Burke