2. In case of war, foreign or domestic, the saving to the Government in prices of articles they must buy, and in transportation of men, munitions of war, supplies, and coal, would be enormous. It is believed that the excess of cost in prices and transportation during this rebellion, occasioned by the want of these works, WOULD MORE THAN PAY FOR THEIR CONSTRUCTION. Nor is this the only loss, but victories no doubt have often been turned into defeats, for the want of proper facilities for the movement of gunboats, of supplies, and munitions, and the rapid concentration of troops and reenforcements. 3. The ability to obtain supplies, and coals, and vessels, from so many points, and especially gunboats, where the coal, iron, and fluxes are in justaposition, would hasten construction, and cheapen prices to the Government. The enormous naval and military power, gained by such works, would tend greatly to prevent wars, foreign or domestic; or, if they did occur, would enable us to conduct them with more economy and success. It is said such vessels can be built on the lakes, and so they can, for lake defence, but they would be liable to capture or destruction there, before completed, by the enemy, and iron vessels, and iron-clads, could not be constructed so cheaply, where there is neither coal nor iron, as in regions like the Delaware, Susquehanna, Alleghany, and Ohio, where these great articles abound, and can be used on the spot, with so much economy. It must be remembered, also, that, if these iron steamers and iron-clads are constructed on the seaboard or the lakes, still, the iron and coal for building them, and the coal for running them, could be supplied much more cheaply, if these enlarged canals were finished. Besides, events are now occurring, and may again, in our history, requiring the immediate construction of hundreds of iron vessels, rams, iron-clads, and mortar boats, calling for all the works on the seaboard, the lakes, the Western rivers, and enlarged canals, to furnish, in time, the requisite number. Rapid concentration of forces, naval and military, and prompt movements, are among the greatest elements of success in war. It will be conceded, that the ability to run gunboats, iron-clads, rams, and mortar boats, through all our lakes, to and from them to all our great rivers, and to connect from both, through such enlarged canals, with the seaboard, and the Gulf, would vastly increase our naval and military power.