The rebels have pickets at every crossing on Pearl River for a distance of 15 miles above and 10 miles below Jackson.

All the wagons are concentrated within 5 miles of Jackson. The rebels are rapidly fortifying their position, and have several heavy guns, which they intend to mount on their works.

Re-enforcements to the number of 10,000 men are excepted within they days.

All supplies are received by way of Meridian. Supplies are very meager. All the rolling stock of the MISSISSIPPI Central, new Orleans, Jackson and Great Northern Railroad, ands the MISSISSIPPI and Tennessee Railroad has been sent up the road, probably to Grenada. The locomotives will number nearly 50 and the cars over 200, all first-class stock. Many of the cars were loaded with machinery and railroad fixtures.

I have traversed nearly the whole State of MISSISSIPPI. There are no troops of consequence in the middle and northern portions of the State, except the commands of Johnston, CHALMERS, gholson, and Ruggles. Nearly the entire population is in arms, and but few men are at home.

For the disposition of Johnston's army, see the diagram,*which is drawn from recollection.

The following are the numbers of such regiments as I have been able to obtain and note down:

Kentucky. -THIRD, fourth, FIFTH, Sixth, seventh, and Eight.

Tennessee. -THIRD, tenth, eighteenth, thirtieth, fortieth, Fiftieth, and Sixtieth.

Arkansas. -First and SECOND (dismounted)Riflemen, first and NINTH Infantry, fourth, twenty-FIFTH, thirty-SECOND, tenth, and the Fourth Arkansas Battalion. These are McNair's brigade.

Texas. -THIRD, sixth, NINTH, and Fifteenth Texas and Whitfield's First Texas Legion(Cavalry)compose Withfields brigade; Seventh Infantry.

Louisiana. -Fourth Battalion and Fourth Regiment.

Mississippi. -Fourteenth, twenty-seventh, twenty-eight, and the Fourth Cavalry.

Georgia. -Twenty-FIFTH and Twenty-seventh Infantry. South Carolina. -Twenty-fourth and Twenty-NINTH Infantry, in Gist's brigade.

North Carolina. -Thirty-eighth Infantry.

Report of Ordnance and Ordnance Stores captured at Jackson, MISS.

CAMP ON BIG BLACK RIVER, MISS., July 29, 1863.

Destroyed by Captain J. D. Farland, acting ordnance officer: 21,000 shot and shell, 425 muskets, 850 sents infantry accouterments, 1,620 rounds 3 1/2-inch rifle-gun ammunition, and 125 rounds 6 1/2-inch rifle-gun ammunition.

Destroyed by provost-marshal: 350 muskets and 500 fixed ammunition for 6 and 12 pounder field guns.

Destroyed by chief of artillery: Two 32-pounder siege guns, rifled(mounted en barbette).

Turned over to assistant quartermaster for transportation: 621 muskets and one 2-inch bronze rifled gun (breech-loading).

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*Not found.

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