From the above you will perceive that there are two entrances into the Pass; the lower one is the one formerly used, but the upper is the one through which our boats passed to-day, and is the best. You will also perceive that the levee is a very heavy one, and, therefore, will require a good deal of work to cut through: but from the fact that there is 8 1/2 feet difference of level between the water inside and out, once opened, the crevasse will enlarge very rapidly. The back country both north and south of the pass is partially over flowed by water from crevasses in the levee. I think boats can go through our cut in three days. The undertaking promises fine results.

Very respectfully, your obedient servant,

J. H. WILSON,

Lieutenant-Colonel, Chief Topographical Engineer.

Lieutenant Colonel John A. RAWLINS,

A. A. G., Hdqrs. Dept. of the Tenn., near Vicksburg, MISS.

YAZOO PASS, MISS., February 4, 1863-8 a. m.

COLONEL: The Pass is open, and a river 75 or 80 yards wide is running through it with the greatest velocity. I wrote you on the evening of the 2nd that by the next (yesterday) evening the water would be let through.

About 7 o'clock, after discharging a mine in the mouth of the cut, the water rushed. The channel was only about 5 feet at first, though the embankment was cut through in two places, with an interval of about 20 feet between them, the cut through which the water was first started being considerably the larger.

By 11 p. m. the opening was 40 yards wide, and the water pouring through like nothing else I ever saw except Niagara Falls. Logs, trees, and great masses of earth were torn away with the greatest ease. The work is a perfect success.

The pilots and the captain of the gunboat Forest Rose think it will not be safe to undertake to run through the Pass for four or five days, on account of the great rapidity and fall of the water. It will take several days to fill up the country so much as to slacken the current.

A prominent rebel living near Helena, General Alcorn, says there will be no difficulty whatever in reaching the Yazoo River with boats of medium size.

Captain Brown will go in with the gunboat at the very earliest moment the passage becomes practicable.

I am, sir, very respectfully, your obedient servant,

J. H. WILSON.

Lieutenant-Colonel, Assistant Inspector-General, &c.

Lieutenant Colonel John A. RAWLINS,

Asst. Adjt. General and Chief of Staff, Hdqrs. Dept. of the Tenn.

HELENA, ARK., February 9, 1863-6 p. m.

GENERAL: Your note of the 7th instant is just received by the steamer Emma.

I have been waiting all day for a boat to return to Vicksburg, in order to report in person the condition of affairs in Yazoo Pass; but as an expedition has already been arranged, and you gave me permission to accompany it, I shall go back to the Pass in the morning.