Capture of a Federal mail steamer--Yankee opinion of the Arkansas.
Jackson, Miss., July 21.
--Lieut. Col. Ferguson of Starke's cavalry, with two companies and a field battery, had captured and destroyed a Federal mail steamer at Skipwith's Landing, eighty miles above Vicksburg.
Col. Ferguson succeeded in obtaining possession of the mail bag from the ship Richmond, en route for Washington.
The contents are highly interesting.
Yankee letters admit the impossibility of capturing Vicksburg without an immense land force, and admit that the Arkansas whipped them.
They evince great terror of the Arkansas.
Her appearance round the bend this morning was the signal for a general stampede.--The bombarding continued slowly to- day.