Brother [from Memphis], in Atlanta, are casting iron into steel, and are making steel-pointed shells. They are the only men in the Confederacy who can do that. They have made 40 rounds for Charleston.

At Columbia, S. C., is the C. S. laboratory, where they make plenty of medicines for the army. There are also other Government machine-shops.

At Charleston I need not say about the fortifications, as our army is in full view of everything, only that at Sullivan's Island are about 12,000 men, including General Anderson's [of Longstreet's corps] brigade [Jenkins' brigade was to go to Charleston, but Anderson's took its place], besides several hundred men who are in the forts. Sumter has only 20 or 30 men, and the citizens of Charleston think that 500 men could storm the place and take it. On the 18th instant Mrs. James Rhett told me that Jeff. Davis had telegraphed to Beauregard to hold the forts at all hazards, that the Spanish fleet would soon be to his relief. The very large gun is fixed now. The cause of its bursting was that General Ripley filled the air-chambers with powder. Immediately after it burst the engineer examined it and reported that it could be fixed. General Beauregard telegraphed to Wilmington, N. C., for the other one. The last-mentioned gun is situated in the heart of the fort on the corner of the city called [before the war began] the "Batteries," facing James and Sullivan's Islands, and the other, if he gets it there, will be stationed close to this one. These guns will only be used in case the rebels should have to give up Fort Moultrie and our fleet should attempt to pass the channel. They have over 3,000 slaves working on James Island, and some on Sullivan's. The State of South Carolina has made 30,000 bags, and they are now filled with sand in the forts. General Beauregard's intention is, if he should have to give up the city, he will put it in ashes, but the mayor, Charles Macbeth, is against it. General Beauregard will make a stand at Summerville [22 miles from the city on the South Carolina railroad], as the above place is a good locality for fortifications. About 3 miles from the city of Charleston are ditches all around it. At Pocotaligo [on the Charleston and Savannah Railroad] are stationed a brigade of volunteers and three regiments of drafted six-months' State troops.

Wilmington, N. C., is a place which could easily be taken. Indeed, the citizens of the place are greatly surprised that the place has not been attacked before this time, but they think it will be taken as soon as Charleston is. Now, Wilmington, being the most important place for Confederate vessels to run in and out, our Government ought to look to it.

At Richmond, Va.: This place is strongly fortified-and it was thought there that if Bragg should not be able to take care of himself with his present force, that Ewell would march with his corps on Knoxville, and A. P. Hill's corps would fall back into the fortifications of Richmond. They are about to finish there four gun-boats something like the Merrimac Numbers 2, but these boats will not draw more than 4 feet of water. The Lady Davis will have ten guns; the Richmond eight, and the two smaller ones six each.

About the Trans-Mississippi Department I can not say much; the rebels say they have 50,000 men there, but from the best information I could get, they can't muster more than 30,000, and the balance are just robbing on their own account, but you can't get them together to fight.

[L. TRAGER.]