I submit the following notes, one from the colonel of the regiment in which Mr. Gaines was a major; and the other from a major in the regiment of which Mr. Hardin was colonel. Both letters are from gentlemen who are now members of Congress. HOUSE OF REPRESENTATIVES, June 27, 1850. SIR; In reply to your note of this date, I state that Major Gaines did not, during the Mexican war, travel through any part of New Mexico. Major Gaines entered Mexico at Camargo, on the Rio Grande; was engaged near Saltillo, until he was captured and taken to the city of Mexico; and thence he returned to the United States by the way of Vera Cruz. I am, sir, very respectfully, &c., HUMPHREY MARSHALL. P.S. In reply to your verbal inquiry, whether Colonel Hardin was in New Mexico, I state, that Colonel Hardin was attached to General Wool’s command, and passed from San Antonio de Bexar, by the Presidio de Rio Grande, Monclova, and Parras, to Saltillo; so that he did not enter New Mexico. H. M. Hon. H. MANN. HOUSE OF REPRESENTATIVES, June 28, 1850. HON. H. MANN. SIR; In reply to your note of this date, I have the honor to say, that I was an officer of the first regiment, Illinois volunteers, commanded by Colonel J.J. Hardin, during the Mexican war, and that during the time Colonel Hardin was in command of the regiment he was not in New Mexico. His nearest point to New Mexico was Monclova or Parras, which was several hundred miles distant. In my opinion, Colonel Hardin was never in New Mexico; he certainly was not in that country during the Mexican war. Respectfully, W. A. RICHARDSON. Now what possible excuse can be offered for these misleading citations? What information would be given of the soil of the Genesee valley of New York, by proving the condition of the sands of Cape Cod? Mr. Webster next quotes, for the second time, the letter of Hugh N. Smith, Esq. This letter, if taken by itself, would render it improbable, in Mr. Smith’s opinion, that slavery would go into New Mexico; but it by no means proves the physical impossibility of its existence there. But what different language has Mr. Smith since held in his address to his constituents in New Mexico itself? I will quote a few passages from this address to show its general drift and intent. “Your state, [New Mexico,] is threatened with dismemberment, and _what is yet more fatal, the introduction of slavery into its bosom_.” (p. 1.)