From Northern Virginia.
The position of our army has undergone no material change since our last report, and if we are correctly advised there has yet been no general move of the forces of the enemy. They have no forces south of the Potomac above Harper's Ferry.Passengers by the Central train yesterday afternoon report that a cavalry fight occurred at or near Leesburg on Sunday last, which resulted in the rout of the enemy with the loss of some sixty prisoners. The extent of the skirmish or the numbers engaged on either side, we were unable to learn.