In this estimate, some allowance, perhaps, should be made, for the greater fertility of the new lands, more recently brought under cultivation; but the difference, on this account, can not be equal to the difference in the crops of the several periods, as the lands, in the older States, in 1820, were yet comparatively fresh and productive.

Again, the dependence of the South upon the North, for its provisions, may be inferred from such additional facts as these: The "Abstract of the Census," for 1850, shows, that the production of wheat, in Florida, Alabama, Mississippi, Louisiana, Arkansas, and Texas, averaged, the year preceding, very little more than a peck, (it was 27/100 of a bushel,) to each person within their limits. These States must purchase flour largely, but to what amount we can not determine. The shipments of provisions from Cincinnati to New Orleans and other down river ports, show that large supplies leave that city for the South; but what proportion of them is taken for consumption by the planters, must be left, at present, to conjecture. These shipments, as to a few of the prominent articles, for the four years ending August 31, 1854, averaged annually the following amounts:

Wheat flourbrls.385,204
Pork and Bacon lbs. 43,689,000
Whiskygals.8,115,360

Cincinnati also exports eastward, by canal, river and railroad, large amounts of these productions. The towns and cities westward send more of their products to the South, as their distance increases the cost of transportation to the East. But, in the absence of full statistics, it is not necessary to make additional statements.

From this view of the subject, it appears that slavery is not a self-sustaining system, independently remunerative; but that it attains its importance to the nation and to the world, by standing as an agency, intermediate, between the grain-growing States and our foreign commerce. As the distillers of the West transformed the surplus grain into whisky, that it might bear transport, so slavery takes the products of the North, and metamorphoses them into cotton, that they may bear export.

It seems, indeed, when the whole of the facts brought to view are considered, that American slavery, though of little force unaided, yet properly sustained, is the great central power, or energizing influence, not only of nearly all the industrial interests of our own country, but also of those of Great Britain and much of the Continent; and that, if stricken from existence, the whole of these interests, with the advancing civilization of the age, would receive a shock that must retard their progress for years to come.

This is no exaggerated picture of the present imposing power of slavery. It is literally true. Southern men, at an early day, believed that the Protective Tariff would have paralyzed it—would have destroyed it. But the abolitionists, led off by their sympathies with England, and influenced by American politicians and editors, who advocated free trade, were made the instruments of its overthrow. No such extended mining and manufacturing, as the Protective system was expected to create, has now any existence in the Union. Under it, according to the theory of its friends, more than one hundred and sixty millions in value, of the foreign imports for 1853, would have been produced in our own country. But free trade is dominant: the South has triumphed in its warfare with the North: the political power passed into its hands with the defeat of the Father of the Protective Tariff, ten years since, in the last effort of his friends to elevate him to the Presidency: the slaveholding and commercial interests then gained the ascendency, and secured the power of annexing territory at will: the nation has become rich in commerce, and unbounded in ambition for territorial aggrandizement: the people acquiesce in the measures of Government, and are proud of the influence it has gained in the world: nay, more, the peaceful aspect of the nations has been changed, and the policy of our own country must be modified to meet the exigencies that may arise.

One word more on the point we have been considering. With the defeat of Mr. Clay, came the immediate annexation of Texas, and, as he predicted, the war with Mexico. The results of these events let loose from its attachments a mighty avalanche of emigration and of enterprise, under the rule of the free trade policy, then adopted, which, by the golden treasures it yields, renders that system, thus far, self-sustaining, and able to move on, as its friends believe, with a momentum that forbids any attempt to return again to the system of protection. Whether the Tariff controversy is permanently settled, or not, is a question about which we shall not speculate. It may be remarked, however, that one of the leading parties in the North gave its adhesion to free trade many years since, and still continues to vote with the South. The leading abolition paper, too, ever since its origin, has advocated the Southern free trade system; and thus, in defending the cause it has espoused, as was said of a certain general in the Mexican war, its editors have been digging their ditches on the wrong side of their breastworks. To say the least, their position is a very strange one, for men who profess to labor for the subversion of American slavery. It would be as rational to pour oil upon a burning edifice, to extinguish the fire, as to attempt to overthrow that system under the rule of free trade. For, whatever differences of opinion may exist on the question of free trade, as applied to the nations at large, there can be no question that it has been the main element in promoting the value of slave labor in the United States; and, consequently, of extending the system of slavery, vastly, beyond the bounds it would otherwise have reached. But the editors referred to, do not stand alone. More than one United States Senator, after acquiring notoriety and position by constant clamors against slavery at home, has not hesitated to vote for free trade at Washington, with as hearty a good will as any friend of the extension of slavery in the country!

All these things together have paralyzed the advocates of the protection of free labor, at present, as fully as the North has thereby been shorn of its power to control the question of slavery. Indeed, from what has been said of the present position of American slavery, in its relation to the other industrial interests of the country, and of the world, there is no longer any doubt that it now supplies the complement of that home market, so zealously urged as essential to the prosperity of the agricultural population of the country: and which, it was supposed, could only be created by the multiplication of domestic manufactures. This desideratum being gained, the great majority of the people have nothing more to ask, but seem desirous that our foreign commerce shall be cherished; that the cultivation of cotton and sugar shall be extended; that the nation shall become cumulative as well as progressive; that, as despotism is striving to spread its raven wing over the earth, freedom must strengthen itself for the protection of the liberties of the world; that while three millions of Africans, only, are held to involuntary servitude for a time, to sustain the system of free trade, the freedom of hundreds of millions is involved in the preservation of the American Constitution; and that, as African emancipation, in every experiment made, has thrown a dead weight upon Anglo-Saxon progress, the colored people must wait a little, until the general battle for the liberties of the civilized nations is gained, before the universal elevation of the barbarous tribes can be achieved. This work, it is true, has been commenced at various outposts in heathendom, by the missionary, but is impeded by numberless hindrances; and these obstacles to the progress of Christian civilization, doubtless will continue, until the friends of civil and religious liberty shall triumph in nominally Christian countries; and, with the wealth of the nations at command, instead of applying it to purposes of war, shall devote it to sweeping away the darkness of superstition and barbarism from the earth, by extending the knowledge of science and revelation to all the families of man.

But we must hasten.