DEAR COLONEL:--I am told that during my absence last week, you passed through this place, and stated publicly that you were in possession of a fact or facts which, if known to the public, would entirely destroy the prospects of N.W. Edwards and myself at the ensuing election, but that through favor to us you would forbear to divulge them. No one has needed favors more than I, and generally few have been less unwilling to accept them; but in this case favor to me would be injustice to the public, and therefore I must beg your pardon for declining it. That I once had the confidence of the people of Sangamon County is sufficiently evident; and if I have since done anything, either by design or misadventure, which if known would subject me to a forfeiture of that confidence, he who knows of that thing and conceals it is a traitor to his country's interest. I find myself wholly unable to form any conjecture of what fact or facts, real or supposed, you spoke. But my opinion of your veracity will not permit me for a moment to doubt that you at least believed what you said. I am flattered with the personal regard you manifested for me; but I do hope that on more mature reflection you will view the public interest as a paramount consideration, and therefore determine to let the worst come. I assure you that the candid statement of facts on your part, however low it may sink me, shall never break the ties of personal friendship between us. I wish an answer to this, and you are at liberty to publish both if you choose. Very respectfully, A. LINCOLN. COL. ROBERT ALLEN.