RICHARD T. SEMMES--One of the prisoners, tried, convicted, and sentenced, for being one of the Chicago Conspirators, is a young man--not over 23 or 24 years of age, a Marylander by birth, and a lawyer by profession. He is a relation of the pirate Semmes (unfortunate in name,) said to be a nephew. He graduated at Yale College with distinction, and his prospects in Chicago were flattering till he connected himself with the Sons of Liberty, and listened to the teachings of older and "wiser" men. Of the witnesses for the defence we have nothing to say, further than most of them were Sons of Liberty. Some of them so far perjured themselves, that now a common lie to them is considered as good as the truth, if not a little better. It is said of Judge H.L. Burnet, that he remarked, had he known what witnesses the defence would have introduced, he would not have called any witnesses for the _Government_--they would have been superfluous. Rather severe, and we will hope he did not say it. Space will not admit of a review of the evidence, and this will be unnecessary for all who will read the sketch of the Judge Advocate's argument. CHAP XXI. ARGUMENT OF THE JUDGE ADVOCATE IN THE CONSPIRACY CASES--CONVICTION OF THE PRISONERS. The evidence in the case before the military commission at Cincinnati, having closed, the counsel who represented the prisoners made their addresses--they cannot be called arguments--and the court adjourned to Tuesday, April 18. As lawyers who have no valid defence, observe it as a policy to attack the Government witnesses with great fury, so Messrs. Hervey and Wilson, true to the ethics of their profession, made a grand assault upon the principal witnesses. Counsellor Hervey, in his harangue, used the following language, which illustrates the line of "argument" for defence: "Some two hundred years ago," said the learned counsel, "there was a man in England who swore away the lives of his fellow citizens by wholesale. His name was Dr. Titus Oates--the man who got up what was called the Popish plot, and by perjury and villainy, consigned many an innocent head to the scaffold. He was assisted by a man who has, as no other judge has, disgraced the ermine--Jeffries, who drank himself to death in the tower, when his co-worker in iniquities and evil deeds with dreadful and condign punishment followed him. The effort of nature to produce so great a monster was so terrible that it required a resting spell of two hundred years before she could produce another such monster in the shape of Dr. I. Winslow Ayer." We forgive him, for he was obliged to seem to do or say something to earn his "fee." There being no arguments for defence, but only such pathetic appeals as only a lawyer, without the least hope, would make, feeling that his clients would expect _something_, we need not take our space to report their remarks.