DEAR SIR,--I now return you the papers reserved from the last post. Our regular answer to Mr. Livingston may well be, that the Attorney General having given an official opinion that the right to the batture is in the United States, and the matter being now referred to Congress, it is our duty to keep the grounds clear of any adversary possession, until the Legislature shall decide on it. I have carefully read Mr. Livingston's printed memoir. He has shaken my opinion as to the line within the road having been intended as a line of _boundary_ instead of its being a line of _admeasurement_ only. But he establishes another fact by the testimony of Fendeau, very fatal to his claim; to wit, that the high-water mark, "batture, ou viennent _battre_ les eaux lorsqu elles sont dans leurs plus grandes croissances," is the universal boundary of private grants on the river. Your observations on his allegations that Gravier's grant must be under the Spanish law, because after the cession of the province by France to Spain, though before delivery of possession, are conclusive. To which may be added, that Louis XIV. having established the Constumes de Paris as the law of Louisiana, this was not changed by the mere act of transfer; on the contrary, the laws of France continued and continue to be the law of the land, except where specially altered by some subsequent edict of Spain or act of Congress. He has not in the least shaken the doctrine that the bed of the river, and all the atterrissements or banks which arise on it by the depositions of the river, are the property of the King by a peculiarity in the law of France; so that nothing quoted from those of Spain or the Roman law is of authority on that point. Affectionate salutations. TO THE SECRETARY OF THE TREASURY. MONTICELLO, May 20, 1808.