COLUMBUS, GA., April 18, 1865.

MAJOR: I have the honor to submit the following brief account of the gun-boat Jackson destroyed at this point yesterday:

This vessel was intended to be one of the most powerful steamers in the West, and would, if fully completed, have been a formidable antagonist for our river gun-boats or rams. She was about 250 feet in length on deck and about forty feet wide; when fully completed would have drawn from six and a half to seven and a half feet of water; was constructed of live oak; hull two feet thick, with ram of fifteen feet solid oak. The face of the deck was to have ben about three and a half feet above water line, but her engines and boilers were below this line. The engines (two) were made here, and were very fine ones; cylinder thirty-six inches and stroke three feet; double connected; four boilers. The armor, which extended just below the water line, was rolled at Atlanta in slabs about six inches wide and two inches thick. These were put on perpendicularly, being curved over the edge of the deck and fastened with bolts two inches in diameter and about two feet apart. The plating was double, breaking joints, and therefore four inches thick. Shot from other vessels could not strike the armor at right angles to its face. The battery consisted of six 7-inch rifled Parrott guns, made at Richmond, Va., and splendidly mounted and finished. They were placed on the main deck, and the gun-room was pyramidal in form, about fort feet long, and twenty feet wide on top. Armor same as on main part of the vessel. There were ten port-holes the two guns aft and the two forward so arranged that they could be used broadside, making the battery three guns on each side when necessary. This gun-room was about nine feet above deck (from floor to roof) and the pilot-house was raised about two feet above the top of gun-room, heavily plated, sloping sides and ends. The pilot was thus in the gunroom. The engines and boilers were immediately under the guns. There were three hatches, one forward and two aft the gun-room. The boat was to be moved by one screw propeller seven and a half feet in diameter. Lieutenant McLaughlin has been engaged nearly if not quite three years in constructing this vessel, and I am informed she would have been ready for active service in two weeks or about the 1st of May. The gun-room armor was not in place, but the engines, boilers and quite a supply of ammunition were on board. When in flames the cables were parted and the gun-boat Muscogee, alias Jackson, floated away to complete destruction. This description is not scientific, but the result of personal observation, sustained by statements of some mechanics who were employed near the navy-yard. It is of course incomplete, and may be in error in some particulars, but I thought it might be of interest in lack of any better one. A small torpedo-boat went down river the day before the capture of this point. She is new and in readiness for active duty.

I have the honor to be, your obedient servant,

E. F. WINSLOW,

Brevet Brigadier-General, Commanding Post.

Major E. B. BEAUMONT,

Asst. Adjt. General, Cavalry Corps, Mil. Div. of the Mississippi.

COLUMBUS, GA., April 18, 1865.

MAJOR: Having been assigned to the command of this city, I have the honor to make the following report of property captured and