There could be no doubt of the power of Congress to declare and levy such an impost on imported slaves for four years to come. The only question therefore was, whether it would be good policy to do so? Mr. MITCHILL contended that it would. On this point he replied to a gentleman from South Carolina, (Mr. LOWNDES,) who had argued that such a tax would discourage agriculture. He contrasted the cultivation of lands by the labor of freemen, with the more expensive management of them by slaves. He compared the husbandry of the Northern and Middle States, with the rural economy of the South. He examined in detail the moderate profits of a plantation on which bread, corn, grass, and live stock, were raised, and the enormous income derived to the proprietor of an estate employed in the culture of tobacco, rice, cotton, and sugar. He examined the smaller expense of feeding, clothing, and housing laborers in warm than in cold climates. It has been computed by men of observation, that a working slave on a cotton plantation would, besides supporting himself, clear for his master a net sum of two hundred dollars a year. On the average course of crops, where the plants were not attacked by the cherille, this estimate was considerably below the mark. And on this conviction he believed there was no important article whatever that would bear an impost so well. Mr. M. then replied to an argument of the gentleman from North Carolina, (Mr. MACON,) that the imposition of the tax would be a recognition of the right to trade in slaves, and bind the nation to protect it with the force of the navy. He considered slavery already recognized in many of the States, and permitted by the constitution. It was a fact that it did exist, and Congress could not put an end to it. But this body might interpose its authority, and discountenance it as far as possible; and by laying the duty as high as the constitution permitted, a very desirable addition would be made to the revenue. Two hundred thousand dollars might be computed to be derived from this sort of merchandise imported into the country. Nor would Congress be bound to protect the African commerce on the high seas; the existing statute would be in force against it; the trade would still be unlawful as far as the power of Congress extended. And under the proposition now under debate, this species of traffic would be so far from receiving encouragement, that it would be punished in cases where Congress could punish it, and taxed in the cases to which the power to punish it did not extend.