[The annexed Letter, which has been cavilled at, as much as copied, is a rationale of the Conspiracy, combined from the Government's own officers. When it was written it was believed to be true: the evidence at the trial has confirmed much of it: I reprint it to show how men's ingenuities were at work to account for the conception and progress of the Plot.] Washington, May 2. Justice and fame are equally and simultaneously satisfied. The President is not yet in his sarcophagus, but all the conspirators against his life, with a minor exception or two, are in their prison cells waiting for the halter. The dark and bloody plot against a good ruler's life is now so fully unraveled that I may make it plain to you. There is nothing to be gained by further waiting; the trials are proceeding; the evidence is mountain high. Within a week the national scaffold will have done its work, and be laid away forever. This prompt and necessary justice will signal the last public assassination in America. Borgia, and Medici, and Brinvilliers, have left no descendants on this side of the world. The conspiracy was both the greatest and the smallest of our cycle. Narrowed in execution to a few, it was understood and connived at by a multitude. One man was its head and heart; its accessories were so numerous that the trouble is not whom to suspect, but whom not accuse. Damning as the result must be to the character of our race, it must be admitted, in the light of facts, that Americans are as secretive and as skillful plotters as any people in the world. The Rye House plot, never fully understood; the many schemes of Mazzini, never fastened upon him sufficiently well for implication, yield in extent, darkness and intricacy, to the republican plot against the President's life and those of his counselors. The police operations prove that the late murder as not a spasmodic and fitful crime, but long premeditated, and carried to consummation with as much cohesion and resolution as the murder of Allessandro de Medici or Henri Quatre. I have been accused of cannonizing Booth. Much as I denounce and deprecate his crime--holding him to be worthy of all execration, and so seeped in blood that the excuses of a century will fail to lift him out of the atmosphere of common felons--I still, at every new developement, stand farther back in surprise and terror at the wonderful resources and extraordinary influence of one whom I had learned to consider a mere Thespian, full of sound, fury, and assertion.