I have duly recieved your favor of the 9th. and proceed to answer the two enquiries made in it on the subject of the Mould board. the 1st. indeed as to the modifications of the simpler form of mould board, is answered in the passage of the Philos. transactions1 where they are mentioned. these modifications are there described, & the reasons are stated which render them necessary. as to the 2d. enquiry respecting the casting them in iron, it was my intention when I wrote that paper to have had it done, but on conversing with judge Peters on the subject, he told me he had tried the mould boards of that material & found them so difficult to fix and2 liable to be broke that he had given them up, & advised me against the attempt.

I have since thought of an alteration in the form of that mould board which would recommend it more to common opinion, and perhaps improve it. in the one described in the Philosophical transactions the toe of the mould board is at a right angle with the bar and is lodged in a duplication of the hinder edge of the wing like a comb-case. but I would propose to make that duplication parallel with the fore-edge of the fin, and 2. or 3. I. back from it. consequently the mould board would be pointed at the toe, instead of being square. to do this, after the pyramidal block is cut out, the fore-right. corner of the block should be sawed off by a line leading from the fore-left corner parallel with3 the fore-edge of the wing. this being done, the bevil is to be formed by exactly the same process as in the first description. the principle of this is rigorously the same with the first; it is only one of those accomodations of it to different circumstances & views, which practice may produce. it will probably enter & pass on with less resistance. it will at the same time lose a beautiful & [advanta]geous effect which I observed produced by the first form, which,4 being fl[at in front] like a wedge, the earth of the furrow rising on it kept it steadi[ly in the ground] without any warbling, and without any effort of the ploughman. [it’s motion was] as smooth as that of a ship through the water in a steady wind & [smooth surface.] Accept my respectful & friendly salutations.