DR. WARDLAW announced to the meeting that the discussion closed for the evening. In doing so he complimented the audience on the very correct manner in which they had observed the rule regarding all manifestation of applause. The attention and interest of the audience were much excited throughout the whole proceedings, indeed, at few meetings have we observed so lively an interest taken in the entire business of an evening, and yet there was not a single instance in which the interference of the chairman was required. On several occasions the rising expression of applause was at once checked by the general good sense of the meeting. SECOND NIGHT--TUESDAY, JUNE 14. MR. THOMPSON, before proceeding with the discusssion, would make one or two preliminary observations. Last evening he had been led into an error, as regarded both number and time, in speaking of the amount of slaves in America at the adoption of the Constitution; and he was anxious that every statement made by him should be without a flaw; and if there should be an error committed he would be the first person to admit and correct it when discovered. He stated that at the adoption of the American Constitution, there were only about three hundred thousand slaves in the United States. There were not many more in 1776, when the states declared themselves independent: in 1788 when the Constitution was settled there were more; and in 1790, there were between six and seven hundred thousand slaves in the United States of America. His error consisted in his subtracting 1776 from 1790, and saying twenty-four years instead of fourteen. He mentioned this error to show that he held a regard to truth to be the ultimate end of their discussion. There was one other preliminary remark. His antagonist had repeatedly said that George Thompson had published himself a martyr. George Thompson never did publish himself a martyr. Mr. Breckinridge, in the course of his speeches last night, had said more of himself than he (Mr. T.) had ever done during all the speeches he had ever made on the question. He had only referred to himself when urgently requested to give an account of his personal experience. He never had a wish to be considered a martyr. If, when he had finished his course here; if, when this probationary scene was over, he was found to have done his duty, he would be fully satisfied. He was not pharasaical enough to imagine that he had performed any works of supererogation. Mr. Breckinridge had said this was not a national question; that slavery in America was not American Slavery; that it was not a national evil; that it was not a national sin; that is was merely a question between the State Legislatures and the slave owners. He (Mr. T.) had said last night, that slavery in America was a national sin, and he would now adduce the reasons for his statement:--First--The American people had admitted the slave states into the Union; and by