[MR. BUCHANAN TO C. COMSTOCK.] WASHINGTON, July 5, 1860. DEAR SIR:— I have received yours of the 3d inst., and although I do not write letters on the subject to which it refers, I have determined to address you a few lines. The equality of the States in the Territories is a truly Democratic doctrine which must eventually prevail. This is all for which I have ever contended. The Supreme Court of the United States,—a coördinate branch of the Government, to which the decision of this question constitutionally belongs, have affirmed this equality, and have placed property in slaves upon the same footing with all other property. Without self-degradation, the Southern States cannot abandon this equality, and hence they are now all in a flame. Non-intervention on the part of Congress with slavery in the Territories, unless accompanied by non-intervention on the part of the Territorial legislatures, amounts to nothing more in effect than to transfer the Wilmot Proviso from Congress to these legislatures. Whilst the South cannot surrender their rights as coequal States in the confederacy, what injury can it possibly do to the Northern States to yield this great Democratic principle? If they should not do this, then we will have the Democratic party divided, South and North, just as the Methodist Church has been divided, and another link binding the Union together will be broken. No person can fairly contend that either assemblage at Baltimore, at the time the nominations were made, was a Democratic National Convention; hence every Democrat is free to choose between the two candidates. These are, in brief, my sentiments. I regret that they so widely differ from your own. You have taken your own course, which you had a perfect right to do, and you will, I know, extend a similar privilege to myself. Yours very respectfully, JAMES BUCHANAN. The sole part that was taken by President Buchanan, in any public manner, in the election of 1860, was in a speech which he made from the portico of the White House, on the evening of July 9th, when a great crowd assembled in front of the mansion and called him out. In the course of his remarks, he said: