“MY DEAR SIR,--An unkindly current of air is often more penetrating than an arrow. From such a shaft I suffered on the night of my address to the Mercantile Library Association, more than a week ago, and no care or skill has been efficacious to relieve me. I am admonished alike by painful consciousness and by the good physician into whose hands I have fallen, that I am not equal to the service I have undertaken on Thursday evening. “Fitly to inaugurate that course of lectures would task the best powers in best health of any man. Most reluctantly, but necessarily, I must lose sight of the inspiring company there assembled in the name of Freedom to sit in judgment on Slavery, and postpone till some other opportunity what I had hoped to say. You, who know the effort I have made to rally for this occasion, will appreciate my personal disappointment. “It is my habit to keep my engagements. Not for a single day have I been absent from my seat in the Senate during the three sessions in which duty has called me there; and never before, in the course of numerous undertakings to address public bodies, at different times and in different places, has there been any failure through remissness or disability on my part. “Pardon these allusions, which I make that you may better understand my feelings, now that I am compelled to depart for the moment from a cherished rule of fidelity. “Ever faithfully yours, “CHARLES SUMNER. “DR. STONE.” Failing to open the course, Mr. Sumner closed it, on his return from Washington in the spring, with the following address, which he was called to repeat in the same hall a few days later. Yielding to friendly pressure, he consented to repeat it at several places in New York, among which was Auburn, the residence of Mr. Seward, by whom he was introduced to the audience in the following words. “FELLOW-CITIZENS,--A dozen years ago I was honored by being chosen to bring my neighbors residing here to the acquaintance of a statesman of Massachusetts who was then directing the last energies of an illustrious life to the removal of the crime of Human Slavery from the soil of our beloved country,--a statesman whose course I had chosen for my own guidance,--John Quincy Adams, ‘the old man eloquent.’