Long before the Secession movement had been developed to the extent just detailed, Congress was in session. It assembled one month after the Presidential election, and fifteen days before the Disunionists of South Carolina met in their ill-starred convention. Up to that time there had been excitement, threats of resistance to the authority of the government in many sections of the South, and an earnest attempt in the Cotton States to promote co-operation in the fatal step which so many were bent on taking. But there had been no overt act against the national authority. Federal officers were still exercising their functions in all the States; the customs were still collected in Southern ports; the United- States mails were still carried without molestation from the Potomac to the Rio Grande. But the critical moment had come. The Disunion conspiracy had reached a point where it must go forward with boldness, or retreat before the displayed power and the uplifted flag of the Nation. The administration could adopt no policy so dangerous as to permit the enemies of the Union to proceed in their conspiracy, and the hostile movement to gain perilous headway. At that juncture Mr. Buchanan confronted a graver responsibility than had ever before been imposed on a President of the United States. It devolved on him to arrest the mad outbreak of the South by judicious firmness, or by irresolution and timidity to plunge the Nation into dangers and horrors, the extent of which was mercifully veiled from the vision of those who were to witness and share them. PENNSYLVANIA AND THE UNION.