It is generally supposed that the defeat of MR. SHERMAN for Speaker of the House of Representatives foreshadows that of Mr. SEWARD before the Black Republican (so called) National Convention. We have very little doubt that the one event will follow the other, though we question somewhat the correlation of cause and effect. True it is that Mr. SHERMAN lost the Speakership, because in endorsing the Helper book he manifested anti-slavery sentiments in the most odious and ultra form. Equally true is it that WM. H. SEWARD has forfeited his strong hold upon Black Republican sympathies, and will probably be set aside for some more available exponent of anti-slavery sentiments, chiefly because that wily politician for once mistook the temper of the people, and blurted out practical abolition in his Rochester speech in its most offensive shape. Yet it is quite possible—nay, extremely likely—that SHERMAN would now occupy the Speaker’s chair in the House, and that SEWARD would be in the safe line of precedents for the Presidential nomination, but for the Harper’s Ferry raid. That abortive effort at an outbreak has done more to injure the ultra Black Republicans, their doctrines and champions, than any other possible event. It aroused so universal a feeling of indignation among all who were not irretrievably committed to the wild and destructive theories of a GARRISON, a PHILIPS and a CHEEVER, as fairly to overwhelm those imprudent party leaders who had prematurely exposed the ultimate designs and inevitable tendencies of Black Republicans. To this cause do we chiefly ascribe the compulsory withdrawal of SHERMAN after two months’ ineffectual efforts to elect him. No candidate holding extreme sectional opinions could have been chosen Speaker in the condition of the public mind superinduced by the Harper’s Ferry affair. To the same cause do we impute the comparative decline of Wm. H. SEWARD. He will not be the nominee of the anti-slavery party, because they will not dare to encounter certain defeat under a standard-bearer who has initiated the doctrine of a perpetual and irrepressible conflict between the North and the South.

From these developments it would appear that the wicked and atrocious experiment of JOHN BROWN, though resulting disastrously for himself and his accomplices, may be productive of great ultimate benefit to the South and to the Union. One of its earliest and most palpable effects has been at the North to terrify every anti-slavery man who is not actually blinded and besotted by sectional fanaticism, and to strengthen conservative citizens of that section in their determination to use every possible endeavor to crush out the foul, hateful and mischievous spirit of abolition. On the one hand the rank and file of the Black Republicans, in their dread of a reaction against them, are repudiating JOHN BROWN and his principles, and assuring the South that beyond a repugnance to the extension of slavery, they bear no animosity whatever to our section of the Union. On the other hand, the mass of those truly national and praiseworthy men who have steadfastly combated fanaticism, avail themselves of the opportunity to demonstrate the inevitable consequences of sectional feuds; to show that the attempt of BROWN and his associates at Harper’s Ferry was the legitimate result of the tenets and teachings of Black Republicanism, and to warn the North against the fatal error it has so long cherished. Thus, we fully believe, the effect at the North has been to compel Black Republicanism materially to moderate its tone and its demands, and at the same time to invigorate and encourage the brave and patriotic spirits who have heretofore striven against the heresy of abolitionism, and in favor of the rights of the South.

With us we can chronicle some things even more gratifying. The South, for almost the first time in her history, has felt the necessity of a union of all her sons in a firm, temperate, but unyielding demand for the recognition of her constitutional prerogatives. While there are extremists at the South, just as there are at the North; while we have amongst us those who are clamorous for disunion, just as in the North there are those who will be satisfied with nothing short of the immediate abolition of slavery, the great body of our people occupy a position at once calm and dignified. They ask for the enjoyment of their indefeasible rights—for nothing more, nor will they be contented with anything less. The South is a unit in this respect. A still more important consequence is visible in the determination of the South to build up her own domestic industry; to depend less on the North; to cease, as far as is practicable, from nourishing and sustaining her foes; to strive to foster the spirit of self-help, self-improvement and commercial independence. Thus while the South will eventually be released from the shackles of utter dependence on the North and will become self-sustaining, she will administer a wholesome and well-merited rebuke to fanatics and incendiaries in the only way in which it can be sensibly felt. When the North is made to appreciate the value of Southern friendship by the losses and the sufferings consequent upon its forfeiture, we may reasonably hope that interest, if not fraternal concord, will admonish that section of the expediency of letting us alone.