Major-General W. T. Sherman and staff; accompanied by Brigadier-General Wilson, arrived at General Burnside's headquarters, at Knoxville, Tenn., at noon to-day.--A most successful reconnaissance was made to Madison Court-House, Va., by four squadrons of the First New York Dragoons, under Major Scott,  demonstrating that no rebel force existed in that quarter. At James City a few rebels, who fled on the approach of the Nationals, were seen. On Thoroughfare Mountain, the rebel signal-station was found in the possession of some thirty or more cavalry, who at once beat a hasty retreat. They were pursued some distance by Major Scott's men, but without capture. It was found to be a good position for its past uses, as well as in turn to be used against them, as from it the position of nearly the whole rebel army can be seen. The destruction was made as complete as possible.--the National iron-clad Weehawken, during a terrific storm, sunk at her anchorage at the entrance of Charleston harbor, S. C., carrying down with her four engineers and twenty-six of her crew.--the merchant steamer Chesapeake, commanded by Captain Willets, was seized by a party of rebels, who had taken passage in her, while on her way from New York to Portand, Maine. The pirates assaulted the crew, killed the engineer, and wounded two other officers, and, after landing the passengers at Partridge Island, ran away with the vessel.