On the Friday night of the murder the departments were absolutely paralyzed. The murderers had three good hours for escape; they had evaded the pursuit of lightning by snapping the telegraph wires, and rumor filled the town with so many reports that the first valuable hours, which should have been used to follow hard after them, were consumed in feverish efforts to know the real extent of the assassination. Immediately afterwards, however, or on Saturday morning early, the provost and special police force got on the scent, and military in squads were dispatched close upon their heels. Three grand pursuits wore organized: one reaching up the north bank of the Potomac toward Chain bridge, to prevent escape by that direction into Virginia, where Mosby, it was suspected, waited to hail the murderers; A second starting from Richmond, Va., northward, forming a broad advancing picket or skirmish line between the Blue Ridge and the broad sea-running streams; A third to scour the peninsula towards Point Lookout. The latter region became the only one well examined; the northern expedition failed until advised from below to capture Atzerott, and failed, to capture Payne. Yet there were cogent probabilities that the assassin had taken this route; far Mosby would have given them the right hand of fellowship. When that guerrilla heard of Booth's feat, said Captain Jett, he exclaimed: "Now, by----! I could take that man in my arms." Washington, as a precautionary measure, was doubly picketed at once; the authorities in all northern towns advised of the personnel of the murderer, and requests made of the detective chiefs in Baltimore, Philadelphia, and New-York, to forward to Washington without delay their best decoys. A court of inquiry was organized on the moment, and early in the week succeeding rewards were offered. An individual, and not the government, offered the first rewards. There were two men without whom the hunt would have gone astray many times. John S. Young, chief of the New-York detective force, a powerful and resolute man, whose great weight and strength are matched by boundless energy, and both subordinate to a head as clear as the keen and searching warrant of his eye. This man has been in familiar converse with every rebel agent in the Canadas, and is feared by them as they fear the fates of Beall and Kennedy. Without being a sensationist, he has probably rendered the cleverest services of the war to the general government. They sent for him immediately after the tragedy, and he stopped on the way for his old police companion, Marshal Murray. The latter's face and figure are familiar to all who know New-York; he resembles an admiral on his quarter-deck; he is a detective of fair and excellent repute, and has a somewhat novel pride in what he calls "the most beautiful gallows in the United States."