I communicate, for the information of Congress, a letter from Cowles Mead, secretary of the Mississippi Territory, to the Secretary of War, by which it will be seen that Mr. Burr had reached that neighborhood on the 13th of January. TH. JEFFERSON. FEBRUARY 10, 1807. _To the Senate and House of Representatives of the United States_: In compliance with the request of the House of Representatives expressed in their resolution of the 5th instant, I proceed to give such information as is possessed of the effect of gunboats in the protection and defense of harbors, of the numbers thought necessary, and of the proposed distribution of them among the ports and harbors of the United States. Under present circumstances, and governed by the intentions of the Legislature as manifested by their annual appropriations of money for the purposes of defense, it has been concluded to combine, first, land batteries furnished with heavy cannon and mortars, and established on all the points around the place favorable for preventing vessels from lying before it; second, movable artillery, which may be carried, as occasion may require, to points unprovided with fixed batteries; third, floating batteries, and fourth, gunboats which may oppose an enemy at his entrance and cooperate with the batteries for his expulsion. On this subject professional men were consulted as far as we had opportunity. General Wilkinson and the late General Gates gave their opinions in writing in favor of the system, as will be seen by their letters now communicated. The higher officers of the Navy gave the same opinions in separate conferences, as their presence at the seat of Government offered occasions of consulting them, and no difference of judgment appeared on the subject. Those of Commodore Barren and Captain Tingey, now here, are recently furnished in writing, and transmitted herewith to the Legislature.