Monticello July 8. 20
Your favor of the 2d has been recieved with the mapping instrument for platting lands by latitude and departure. it bears no analogy at all to the method of platting explained by me to mr Girardin some years ago. that was in the usual mode of course and distance, and was merely a substitution of East & West lines instead of Meridians, transforming those lines from station to station by the triangled parallel ruler; & applying the protractor to the edge of the ruler, at the new station instead of drawing the line actually on the paper. this method is quicker, neater, and less liable to errors than the common, but is a more manual abridgement of trouble, not at all claiming the honors of invention. Having never been in the pract[. . .] platting in the way to which your instrument is applicable, [. . .] not a judge of the degree of convenience to be derived from [. . .] I return it with assurances of my respect.
DLC: Papers of Thomas Jefferson.