Extract from Thomas Jefferson to David Rittenhouse

I send for your acceptance some sheets of drawing-paper, which being laid off in squares representing feet, or what you please, saves the necessity of using the rule & dividers in all rectangular draughts & those whose angles have their sines & co-sines in the proportion of any integral numbers. using a black lead pencil, the lines are very visible, and easily effaced with Indian rubber to be used for any other draught

RC (Privately owned). Published in PTJ, 19:584.