SEPTEMBER 19TH.—And God has blessed us even more abundantly than we supposed. The rumor that our invincible Stonewall Jackson had been sent by Lee to Harper’s Ferry, and had taken it, is TRUE. Nearly 12,000 men surrendered there on the 15th inst., after the loss of two or three hundred on their side, and only three killed and a few wounded on ours. We got 90 guns, 15,000 stand of small arms, 18,000 fine horses, 200 wagons, and stores of various kinds, worth millions.