Cardboard half-circle, a long black thread pierces card at center of its arc. Reverse bears printed: 'Directions for using the protractor, entered according to the act of Congress in 1853'.
Material
Signed on the front: Published by Henry Whipple & Son, Book and Chart Sellers 190 Essex St. Salem, Mass. Marked along the strait edge: Marine-Protractor | William Leavitt. | Navigation School | Salem
