I am of the opinion that the cotton bridge is equal, if not superior, to the pontoon, being much steadier and easily constructed. Leaving this point, I arrived in rear of Vicksburg, and will report at a future time. I am under many obligations to Captain Wiles, while he was connected with the pioneers. He is one of the most efficient and practical men I ever met with. you Lieutenant [Alexander] Scales, his successor, and Sergeant Ross, who had charge of the negroes, I am indebted for their indomitable energy and perseverance in the construction of work.

I have the honor to remain, your obedient servant.

S. R. TRESILLIAN,

DIVISION Engineer THIRD DIVISION, SEVENTEENTH Army Corps.

Lieut. Colonel JAMES H. WILSON.

First Lieutenant of Engineers, department of the Tennessee.

HDQRS. CHIEF ENGINEER, THIRD DIV., SEVENTEENTH A. C.,
Vicksburg, MISS. August 17, 1863.

SIR: I have the honor to report the part taken by me during the late siege of Vicksburg, resulting in its capitulation. On May 19, I arrived at the junction of the main Jackson and Warrenton roads, with Major-General Logan. By his orders, about 3 p. m. I made a reconnaissance of the front, and communicated with. Brigadier General John E. Smith and Stevenson. I found General Stevenson's command under the crest of the first ridge, on the left of the Jackson road, in line of battle, himself in advance, near the cotton-gin, which stood on the left of the ridge, afterward known as Longan's headquarters, or Siege Battery Logan. At this time, to the rear of his left and in advance of the Warrenton road, a battery was being put into position. I found Brigadier-General Smith's command in line in the ravine to the left of the point afterward occupied by General Ransom's first battery, with Brigadier- General Ransom's command in line in the ravine to the left of the point afterward occupied by General Ransom's command on his right. General Smith I found in front, taking a sketch of the enemy's position. From these two points of observation I obtained a pretty accurate general outline sketch of the entire front of the THIRD DIVISION. This was the first position occupied by the DIVISION. On the morning of May 20, with portion of the DIVISION pioneer corps, I constructed a sunken battery and platforms for two pounder manned by a detachment of the First U. S. Infantry, under the command of Captain Offley. At the same time, farther to the left, on the same ridge, the First Missouri Battery of 10 pounder Parrott guns, commanded by Lieutenant McMurray, was put in position. The following night the First and THIRD Brigades, of the THIRD DIVISION, were advanced to the ravine in front of this position, on the right and left, respectively, while Major Stolbrand, chief of artillery, brought a portion of the artillery forward proportionately. This was the SECOND position of the DIVISION. On the morning of the 21st, I made a reconnaissance of our left front. In the afternoon, according to orders received from Major-General McPHERSON, I procured suitable lumber form a cotton-gin and the palings about the Sherman Hospital, put the mechanics of the pioneer corps at work, and before daylight had ready for use forty scaling-ladders, varying in length from 16 to 22 feet, enough for one man to carry,