Under the act of 30th April last, authorizing the President to cause a survey to be made, with the necessary plans and estimates, of such roads and canals as he might deem of national importance in a commercial or military point of view, or for the transportation of the mail, a board has been instituted, consisting of two distinguished officers of the Corps of Engineers and a distinguished civil engineer, with assistants, who have been actively employed in carrying into effect the object of the act. They have carefully examined the route between the Potomac and the Ohio rivers; between the latter and Lake Erie; between the Alleghany and the Susquehannah; and the routes between the Delaware and the Raritan, Barnstable and Buzzards Bay, and between Boston Harbor and Narraganset Bay. Such portion of the Corps of Topographical Engineers as could be spared from the survey of the coast has been employed in surveying the very important route between the Potomac and the Ohio. Considerable progress has been made in it, but the survey can not be completed until the next season. It is gratifying to add, from the view already taken, that there is good cause to believe that this great national object may be fully accomplished. It is contemplated to commence early in the next season the execution of the other branch of the act--that which relates to roads--and with the survey of a route from this city, through the Southern States, to New Orleans, the importance of which can not be too highly estimated. All the officers of both the corps of engineers who could be spared from other services have been employed in exploring and surveying the routes for canals. To digest a plan for both objects for the great purposes specified will require a thorough knowledge of every part of our Union and of the relation of each part to the others and of all to the seat of the General Government. For such a digest it will be necessary that the information be full, minute, and precise. With a view to these important objects, I submit to the consideration of the Congress the propriety of enlarging both the corps of engineers--the military and topographical. It need scarcely be remarked that the more extensively these corps are engaged in the improvement of their country, in the execution of the powers of Congress, and in aid of the States in such improvements as lie beyond that limit, when such aid is desired, the happier the effect will be in many views of which the subject is susceptible. By profiting of their science the works will always be well executed, and by giving to the officers such employment our Union will derive all the advantage, in peace as well as in war, from their talents and services which they can afford. In this mode, also, the military will be incorporated with the civil, and unfounded and injurious distinctions and prejudices of every kind be done away. To the corps themselves this service can not fail to