Letter from the Secretary of War, transmitting, in connection with his letter of the 18th ultimo, a communication from the Chief of Engineers, submitting copy of report of the board of engineers for fortifications and for river and harbor improvements; the suggestion of the Chief of Engineers that the unexpended balances of the appropriations of June 18, 1878, and March 3, 1879, be applied to the improvement of the mouth of Red River, and dredging, &c. May 4, 1880. -- Referred to the Committee on Commerce and ordered to be printed