HDQRS. FIFTH DIVISION, ARMY OF THE TENNESSEE, Chewalla, June 5, 1862.

Col. J. C. KELTON:

SIR: The major-general commanding has instructed me to make close inquiry as to the geography and resources of the line of country west hence to Memphis. I experience great difficulty, as, for good reasons, I exclude all citizens from my lines, and command all farmers to remain at home, and on no account to go more than a mile away. It is all-important at this time that we mask our movements. I have made an exception in the case of a man named Dean, who was formerly a foreman in charge of a repair gang on the Charleston and Memphis Railroad. I sent him yesterday to Pocahontas, and he has just got back, bringing here the following positive information: No county maps of McNairy or Hardeman Counties could be got. A Mr. Colson writes me that he assisted in the surveys of the railroad, but that all notes and maps were returned to the main office at Memphis, and that he has nothing but his memory. This he prefers not to put on paper, but is willing to impart orally. He reports two structures between Pocahontas and Grand Junction as burned or destroyed. Bridge 1 1/2 miles west of Pocahontas; iron on stone piers; five spans, of 60 feet each [over Muddy], down.

A long piece of wooden trestle over Purtie's Creek, 7 1/2 miles west of Pocahontas, burned, but early repaired.

Road from Grand Junction to Memphis still in running order. One train came out to the Junction yesterday. Some troops, number unknown, at Junction, and two cavalry scouts were within 2 miles of Pocahontas last night.

Railroad office books, papers, spare locomotives, cars, &c., being removed from Memphis to upland called Osceola, 40 miles south of Grenada, where a large amount of side track is being made. Much excitement is in West Tennessee about the burning of cotton. One riot, in which 4 soldiers were killed. Talk in Pocahontas of an organization to protect cotton against the order to burn.

Mr. Dean himself saw the structures this side of Pocahontas. Hatchie Bridge, 1 1/4 miles east of Pocahontas; bridge burned; span, 162 feet; depth of water, 6 to 8 feet; length of trestle west of bridge, 312 feet, of which forty-two bents, of about 18 feet, are burned. Length of trestle east of bridge, 337 feet, of which fourteen bents are burned.

Tuscumbia Bridge, 162 feet, burned; water, 4 to 6 feet; trestle east, 370 feet; bents destroyed, 5. He also notes Hardcastle trestle of 230 feet long; number of bents destroyed, 5.

Thus it will be seen that na immense quantity of work must be done to put this road in order to the Junction. All the timber must be got out, as there is none prepared, and the saw-mills at Pocahontas are stopped.

As soon as I get the maps, which Colonel Thom is preparing, I will make close inquiry into the country road, with the resources as to forage, and report fully. I heard of another hand car across Tuscumbia, and have sent a party to get it across somehow to-night.

I have a regiment at Young's Bridge [burned], on the Kossuth road, 2 1/2 miles west of this, engaged in erecting a new bridge, and have notified General Hurlbut of General Halleck's order that he prepare one at Smith's old bridge, so as to be ready to move on Kossuth at short notice. Kossuth is 10 1/2 miles below here.

By to-morrow I will have all the locomotives and works of the road.