The action of the Black Republican Convention on the Presidential question has confirmed singularly and opportunely the remarks made in our last issue on the influence of conservative views upon the party politics of the day. The Democratic National Convention tacitly acknowledged this influence by strenuously resisting, even to a partial disruption of its strength, the efforts of the extreme South to force upon it the recognition and endorsement of a sectional platform. It was likewise felt in the conduct of the Union Convention, which contented itself by simply proclaiming obedience to the Constitution and the laws as the test and touchstone of political fealty. Finally, the Black Republicans of Chicago, although avowedly a sectional faction, based upon a single prominent idea—that of the limitation of slavery—have been so directly subjected to the same potent agency as to promulgate a programme of principles which, with few exceptions, would apply quite as readily to one portion of the country as another. Instead of breathing hatred and persecution against the South—instead of classing slavery with polygamy, and resolving upon the annihilation of both as twin relics of barbarism, the Black Republicans denounce forays like that of JOHN BROWN in emphatic language, disclaim the slightest intention of interfering with the institutions of the South, and confine the assertion of their peculiar tenets to the denial of the duty of Congress to protect slavery, and to the expression of an opinion in favor of the immediate admission of Kansas into the Union. These are striking evidences of the power of popular sentiment in moderating the frantic zeal of faction.

It is, however, in the choice of a Presidential candidate that the Black Republicans have furnished a signal manifestation of their determination to avoid extremes. Having before them WM. H. SEWARD, beyond all doubt the AJAX TELAMON of the party; the man who gave it being and breath; who nurtured its sickly infancy and fostered it with earnest solicitude until it attained its present formidable proportions; who dared boldly and bravely in the face of an assembled multitude to avow its ultimate purposes; who originated the axiom of the existence of an irrepressible conflict between slavery and freedom; who is the head and front of Black Republicanism; who in the United States Senate is ever its cool, watchful, wary, sagacious, bland, keen and indefatigable advocate; who, in fine, by his talent, his position, his high standing, and his prolonged services has ever been deemed pre-eminently worthy the most exalted honors his party can bestow, they have thrust him aside to make room for ABRAHAM LINCOLN, of Illinois. In thus acting, Black Republicanism has evinced base ingratitude, but crafty and prudent policy. It has treated its founder most vilely, but it has added materially to its own prospects of success.

We predicted long ago the defeat of SEWARD in the Chicago Convention. We saw that he was opposed by two redoubtable antagonists—first, the conservative element of his party, and next, the power and influence of the West. The former combated his claims because his candidature would frighten off all who were not fully committed to the ultra doctrines of the party. The latter considered that he was decidedly weak in the West, and could not carry any of the doubtful States. The two influences combined proved sufficient to effect his overthrow. But the Chicago Convention did not complete its work when it eliminated SEWARD. The subsequent nomination of LINCOLN was a master stroke of political craft. Mr. LINCOLN belongs to the moderate wing of the Black Republicans. He was formerly a Whig member of Congress, and then but slightly tinctured with anti-slavery notions. On the dissolution of the Whig party, he joined the ranks of the Black Republicans, and took a prominent position in that party. He rendered himself particularly conspicuous by the zeal and ability he displayed in the canvass last year for U. S. Senator from Illinois, when he and DOUGLAS traveled throughout the State, addressing the people alternately. Although DOUGLAS triumphed, he had confessedly in LINCOLN a foeman worthy of his steel, and ever since that memorable struggle the Black Republican sheets of the West and Northwest have placed LINCOLN on the list of aspirants for the Chicago nomination. He is a man of agreeable manners, a ready and forcible speaker, self-made and self-taught, and personally popular among the hardy sons of the West.

Another controlling motive for the choice of the Convention is to be found in local influence. The Black Republicans know that the doubtful States are Pennsylvania, Illinois and Indiana. SEWARD would have been beaten thirty thousand votes in the first, and could not possibly have carried either of the others. LINCOLN will undoubtedly prove a powerful candidate in Illinois and Indiana, and will run in Pennsylvania at least as well as any other Black Republican. His strength, in short, is in the debatable States. Anbody can receive the electoral votes of Massachusetts and Vermont, while New York would not be more certain for SEWARD than for LINCOLN; but there are votes which must be had to secure the success of the candidate, and those votes are cast precisely by those States where LINCOLN is best known and most popular. Hence his nomination. We regard him as a formidable competitor for the Presidency, and as at present advised, we consider that should the Democrats reunite at Baltimore, the nomination of LINCOLN will impose on them the necessity of looking to the West for an opponent. We should not be surprised to see DOUGLAS pitted once more upon a broader field against his ancient foe.