Your favor of the 21st. came duly to hand, and I admit all your corrections with great thankfulness. The first was an inaccuracy of expression. I meant to say that there existed not in nature any one species of body or thing, such as a digit, palm, span, foot, cubit, barley corn &c. which furnished us with a constant uniform dimension. I have corrected it accordingly. The statement of the expansion of the rod was an error in having multiplied the number only once, instead of twice, by 12. I have stated in a note the reason for continuing the double expressions, and having made the other corrections, all of which fall within the first sheet, I send you a third edition of that sheet, to be substituted in place of the former. I do this in order to save time, wishing to have your corrections of my corrections. I am in hopes this will not be the last trouble which this business is to give you, and that you will feel some interest in seeing that we set out right. I am my dear sir with great affection your sincere friend & servt.,