Pushing the Outposts.
--A Washington correspondent of the Baltimore Sun writes as follows in regard to a rumor which has been circulated here:‘ Some persons who reside across the river, in Virginia, have the impression that a military reconnaissance has been made of the heights commanding this city, by officers in the service of the Confederate States, and this idea may be urged as a ground for occupying them by the Government troops. Indeed, it is stated that pickets will be pushed out in that direction. As a very large force is to be concentrated at this key position, those heights will probably be seized by one party or another as soon as Virginia acts. As I write a full company of Washington Light Infantry are marching past, and some post in the vicinity looking towards Maryland is their probable destination. Things are conducted here in the most secret manner possible. At some of the Departments intercourse with subordinate clerks is entirely cut off.
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