SIR: The undersigned would respectfully call your attention to their contract of the 3d of March, 1852, with the department, for the transportation of the United States mails between Vera Cruz, in Mexico, and Acapulco, San Diego, Monterey, and San Francisco. By this contract it was stipulated and intended to transport the mails semi-monthly between New Orleans and San Francisco in sixteen days, (consecutively,) and surety for a large amount was given for the faithful performance of the service. By the terms of this contract it was subject to the approval of Congress, and also to an appropriation by the same. The undersigned immediately prepared to perform the service in order to satisfy the requirements of the department, and also to save their surety harmless from their heavy obligation. Steamers were provided for the service on the Pacific ocean, and one of the undersigned proceeded to Mexico to take charge of the line between Vera Cruz and Acapulco. Horses, mules, harness, stages, wagons, and other materiel, were rapidly collected to furnish all that was required for the 384 miles of land conveyance across Mexico. At the same time a small letter mail was established, which commenced operations in July of the same year. By this method it was designed to transmit, rapidly, intelligence between the Atlantic and Pacific cities of the Union until the stages and other materiel, were properly placed on the line. Under this temporary arrangement, newspapers and letters were carried between California and New Orleans in fourteen, thirteen, and twelve-and-a-half days. Had the arrangement been completed for connecting with the steamers at Vera Cruz and Acapulco, in no instance would the time have exceeded thirteen days, as the distance by land across Mexico, from sea to sea, was performed with great ease and security in less than three days. Frequent experiments were made on parts of the Mexican road to test the time required for the transportation of the mails when the stages were placed on the route, and it was found that as soon as the mails were transported in the vehicles prepared for that purpose, the time would not exceed forty-eight consecutive hours between Vera Cruz and Acapulco.