Scale rule
This scale rule was identified by Eliza Parke Custis Law, Martha Washington's granddaughter, as the "Box rule from the writing desk of my lamented grandmother." While Mrs. Washington may have used it for marking straight lines, laying out a grid on which to plot a needlework design, or measuring short lengths, the complexity of the scales indicate that it was likely originally part of a pocket set of drafting instruments manufactured for use by draftsmen, surveyors, and other gentleman-professionals. Mrs. Washington may have obtained this rule from one of the instrument sets owned by her husband.
See also W-220.
Published ReferencesCarol Borchert Cadou, The George Washington Collection: Fine and Decorative Arts at Mount Vernon (New York: Hudson Hills Press, 2006), 202-203.