In presenting the great argument of the Hon. John A. Bingham, Assistant Judge-Advocate, on the trial of the assassins, the author feels that he does not need to offer an apology to his readers, notwithstanding its length. In addition to what he has already said by way of commending it to the careful perusal of his readers, he will add by way of preface, the following extracts from Barnes's 40th Congress, Vol. 1, showing the light in which that great effort was viewed by competent judges at the time; and also giving extracts from his great argument before the United States Senate on the articles of impeachment found against Andrew Johnson, President of the United States, for high crimes and misdemeanors, in vindication of the high encomiums bestowed by him on this distinguished statesman and advocate. EXTRACTS FROM "THE FORTIETH CONGRESS OF THE UNITED STATES." BY WILLIAM H. BARNES:--1ST VOL., 40TH CONGRESS. Mr. Bingham served as Special Judge Advocate in the great trial of the conspirators, who were tried for the assassination of Abraham Lincoln, etc. Immense labor devolved upon him during this difficult and protracted trial, and for eight weeks his arduous duties allowed him but brief intervals of rest. He occupied nine hours in the delivery of the closing arguments, in which he ably elucidated the law and the testimony in the case, and conclusively proved the guilt of the conspirators. Mr. Bingham's success in this great trial attracted general attention, and awakened a wide-spread curiosity to know his history. Soon after the close of the trial, a correspondent of the _Philadelphia Press_, having expressed the deep interest he had felt in arriving at a well founded conclusion as to "the guilt of the conspirators and the constitutionality of the court," wrote as follows:--