TO MR. HAY. WASHINGTON, May 28, 1807. DEAR SIR,--I have this moment received your letter of the 25th, and hasten to answer it. If the grand jury do not find a bill against Burr, as there will be no examination before a petty jury, Bollman's pardon need not in that case to be delivered; but if a bill be found, and a trial had, his evidence is deemed entirely essential, and in that case his pardon is to be produced before he goes to the book. In my letter of the day before yesterday, I enclosed you Bollman's written communication to me, and observed you might go so far, if he prevaricated, as to ask him whether he did not say so and so to Mr. Madison and myself. On further reflection I think you may go farther, if he prevaricates grossly, and show the paper to him, and ask if it is not his handwriting, and confront him by its contents. I enclose you some other letters of Bollman to me on former occasions, to prove by similitude of hand that the paper I enclosed on the 26th was of his handwriting. I salute you with esteem and respect. TO COLONEL MONROE. WASHINGTON, May 29, 1807. DEAR SIR,--I have not written to you by Mr. Purviance, because he can give you _vivâ voce_ all the details of our affairs here, with a minuteness beyond the bounds of a letter, and because, indeed, I am not certain this letter will find you in England. The sole object in writing it, is to add another little commission to the one I had formerly troubled you with. It is to procure for me "a machine for ascertaining the resistance of ploughs or carriages, invented and sold by Winlaw, in Margaret street, Cavendish Square." It will cost, I believe, four or five guineas, which shall be replaced here instanter on your arrival. I had intended to have written you to counteract the wicked efforts which the federal papers are making to sow tares between you and me, as if I were lending a hand to measures unfriendly to any views which our country might entertain respecting you. But I have not done it, because I have before assured you that a sense of duty, as well as of delicacy, would prevent me from ever expressing a sentiment on the subject, and that I think you know me well enough to be assured I shall conscientiously observe the line of conduct I profess. I shall receive you on your return with the warm affection I have ever entertained for you, and be gratified if I can in any way avail the public of your services. God bless you and yours. TO M. SILVESTRE, SECRETAIRE DE LA SOCIETE D'AGRICULTURE DE PARIS. WASHINGTON, May 29, 1807.