Under date of July 3, 1796, Mr. Jefferson wrote to Jonathan Williams: "You wish me to present to the Philosophical Society the result of my philosophical researches since my retirement. But, my good Sir, I have made researches into nothing but what is connected with agriculture. In this way I have a little matter to communicate, and will do it ere long. It is the form of a mould-board of _least resistance_. I had some years ago conceived the principle of it, and I explained it then to Mr. Rittenhouse. I have since reduced the thing to practice, and have reason to believe the theory fully confirmed. I only wish for one of those instruments used in England for measuring force exerted in the drafts of different ploughs, etc., that I might compare the resistance of my mould-board with that of others. But these instruments are not to be had here. In a letter of this date to Mr. Rittenhouse I mention a discovery in animal history, very signal indeed, of which I shall lay before the society the best account I can, as soon as I shall have received some other materials collecting for me. "I have seen, with extreme indignation, the blasphemies lately vended against the memory of the father of American philosophy. But his memory will be venerated as long as the thunder of heaven shall be heard or feared." March 27, 1798, Jefferson wrote to Mr. Patterson: "In the life time of Mr. Rittenhouse, I communicated to him the description of a mould-board of a plough, which I had constructed, and supposed to be what we might term the _mould-board of least resistance_. I asked not only his opinion, but that he would submit it to you also. After he had considered it he gave me his own opinion that it was demonstratively what I had supposed, and I think he said he had communicated it to you. Of that however, I am not sure, and therefore, now take the liberty of sending you a description of it, and a model which I have prepared for the Board of Agriculture of England, at their request. Mr. Strickland, one of their members, had seen the model, also the thing itself in use on my farm, and thinking favorably of it, had mentioned it to them. My purpose in troubling you with it is to ask you to examine the description rigorously, and suggest to me any corrections or alterations which you may think necessary. I would wish to have the idea go as correctly as possible out of my hands. I had sometimes thought of giving it into the Philosophical Society, but I doubted whether it was worthy of their notice, and supposed it not exactly in the line of their publications. I had therefore contemplated sending it to some of our agricultural societies, in whose way it was more particularly, when I received the request of the English board. The papers I enclose you are the latter part of a letter to Sir John Sinclair, their president. It is to go off by packett, wherefore I wish to ask the favor of you to return them with