Exceptionally rare Colonial American navigator’s backstaff, alternatively known as a Davis Quadrant. This very scarce example is of classic form with the arcs made of native American fruitwood and the limbs of lignum vitae. The cross brace is signed “Made By Benjamin King In * Newport Rhode Island 1764” contained within a rectangular border embellished with stars and fleur-de-lis designs. There is a blank ivory nameplate inlaid on the long limb. The large arc is graduated in degrees, marked from 90 - 65 on the upper side of the scale and 0 - 25 on the lower. Each degree is subdivided to 10 arc minutes on a diagonal allowing for extrapolation to 1 arc minute. The bottom of the arc is also marked in degrees from 0 up through 25 divided by 6ths (10 arc minutes). Both ends of the scale are finely decorated with impressed stars and the bottom has the traditional “crook” for grasping while taking a sighting. The small arc is calibrated starting at the top in single degrees from -5 through 60 downward. The sum of the two arcs being 90 degrees, hence the name Davis “quadrant.” The reverse of the large arc is atypically marked with a number of predetermined values. It consists of a table marked “L” and “D” at the top of the x axis and 1 through 4 on the bottom. The y axis is marked ¼, ½ ¾ and 1 on the left. These values presumably relate to sun sightings. This instrument exhibits outstanding craftsmanship in its construction. All joints are mortise and tenon held with small brass pins. The three vanes are professional quality replacements. This instrument measures 25 ¼ inches long and the large arc is 12 ¾ inches across while the small arc is 9 ½ inches.
Collection
Instruments Collection
Made/Created
Artist
King, Benjamin
Date made
1764
Place
City
Newport, RI
State/Province
Rhode Island
Country
USA
Continent
North America
Ocean
East Coast of North America, Atlantic Ocean, World Ocean
Lexicon
Nomenclature 4.0
Nomenclature Primary Object Term
Backstaff
Nomenclature Sub-Class
Navigational Equipment
Nomenclature Class
Surveying & Navigational T&E
Nomenclature Category
Category 05: Tools & Equipment for Science & Technology
