From Fredericksburg.
Fredericksburg, Jan. 23
--The Yankees are building immense warehouses at Aquia Creek, repairing and refilling the railroad to the point opposite this place, and building buts and other more permanent conveniences for their army.
These preparations, together with the erection of heavy batteries in front, indicate that their present line has been established as the permanent base of operations for the winter.
A new earthwork, with several guns in position, just below Falmouth, was visible yesterday.
Considerable bodies of troops have been moving up the opposite bank for two or three days past.
A large dwelling-house, owned by Sidney Owens, was burnt yesterday morning.
The fire caused a loaded shell, that had been thrown in during the late battle, to explode.
The long roll was beat on both sides of the river, and the Yankees, as well as ourselves, fell immediately into line of battle, and for a time considerable excitement prevailed. 