Immediately after the adjournment of Congress, today, PRESTON S. BROOKS, of South Carolina, a member of the Lower House, entered the Senate Chamber, and approaching the seat of Mr. SUMNER, struck him a powerful blow with a cane, at the same time accusing him of libeling South Carolina and his great bearded relative, Senator BUTLER. Mr. SUMNER fell from the effects of the blow, and BROOKS continued beating him. Mr. SUMNER soon recovered sufficiently to call for help, but no one interposed, and BROOKS repeated the blows until Mr. SUMNER was deprived of the power of speech. Some eyewitnesses state that BROOKS struck him as many as fifteen or twenty times. Mr. SUMNER was sitting in an armchair when the assault was made, and had no opportunity to defend himself. After his assailant desisted, he was carried to his room, but the extent of his injuries are not yet ascertained. Various opinions on the subject are expressed, many applauding and some denouncing the assault as a cowardly attempt to beat down freedom of speech. Mr. BROOKS has been complained of by Mr. Wm. [name illegible] on whose oath Justice HOLLINGSHEAD required BROOKS to give bail in the sum of [amount illegible] as security for his appearance tomorrow afternoon. Mr. SUMNER has several severe but not dangerous wounds on his head. The cane used by BROOKS was shattered to pieces by the blows. When the attack was made there were, probably, fifteen or twenty persons present, including Messrs. CRITTENDEN, FOSTER, TOOMBS, FITZPATRICK, MURRAY, MORGAN, and other members of Congress, together with Governor GORMAN, several offices of the Senate and some strangers. The attack was so sudden and so unexpected that Mr. SUMNER had no opportunity whatever to place himself in a defensive attitude. The first blow given him by Mr. BROOKS stunned him, and the thick gutta-percha stick which was used by Mr. BROOKS, was broken into many pieces by the time the assault terminated. Messrs. CRITTENDEN, TOOMBS, MURRAY, and others interfered as soon as they could, and probably prevented further damage. The greatest excitement prevailed. Mr. SUMNER sank perfectly unconscious to the floor, where he lay bloody and dreadfully bruised, till raised by his friends. Mr. Sumner s physicians say his wounds are the most severe flesh ones that they ever saw on a man s head, and deny his friends admission to him.