Surmises have been hazarded that this enterprise is to receive aid from certain foreign powers. But these surmises are without proof or probability. The wisdom of the measures sanctioned by Congress at its last session had placed us in the paths of peace and justice with the only powers with whom we had any differences, and nothing has happened since which makes it either their interest or ours to pursue another course. No change of measures has taken place on our part; none ought to take place at this time. With the one, friendly arrangement was then proposed, and the law deemed necessary on the failure of that was suspended to give time for a fair trial of the issue. With the same power, negotiation is still preferred, and provisional measures only are necessary to meet the event of rupture. While, therefore, we do not deflect in the slightest degree from the course we then assumed, and are still pursuing, with mutual consent, to restore a good understanding, we are not to impute to them practices as irreconcilable to interest as to good faith, and changing necessarily the relations of peace and justice between us to those of war. These surmises are, therefore, to be imputed to the vauntings of the author of this enterprise, to multiply his partisans by magnifying the belief of his prospects and support. By letters from General Wilkinson, of the 14th and 18th of September, which came to hand two days after date of the resolution of the House of Representatives, that is to say, on the morning of the 18th instant, I received the important affidavit, a copy of which I now communicate, with extracts of so much of the letters as come within the scope of the resolution. By these it will be seen that of three of the principal emissaries of Mr. Burr, whom the general had caused to be apprehended, one had been liberated by _habeas corpus_, and the two others, being those particularly employed in the endeavor to corrupt the general and army of the United States, have been embarked by him for our ports in the Atlantic States, probably on the consideration that an impartial trial could not be expected during the present agitations of New Orleans, and that that city was not as yet a safe place of confinement. As soon as these persons shall arrive, they will be delivered to the custody of the law, and left to such course of trial, both as to place and process, as its functionaries may direct. The presence of the highest judicial authorities, to be assembled at this place within a few days, the means of pursuing a sounder course of proceedings here than elsewhere, and the aid of the executive means, should the judges have occasion to use them, render it equally desirable for the criminals as for the public, that being already removed from the place where they were first apprehended, the first regular arrest should take place here, and the course of proceedings receive here its proper direction. SPECIAL MESSAGE.--JANUARY 28, 1807.