There is good reason to anticipate, that important assistance will be rendered to the emigrants, not only by the missionary societies of Europe, but also by those governments which have taken an interest in the suppression of the slave trade, and which are desirous of opening channels for their commerce, and marts for their manufactures, on the western coast of Africa. It is estimated, that by the time when the first two ships are to be finished and ready for sea, there will be a large body of emigrants ready to take passage in them, and that for the next two years each ship will take from 1000 to 1500 passengers on each voyage, or from 8,000 to 12,000 in each of those years. To furnish each family, intending to devote themselves to agricultural pursuits, with a dwelling-house suitably furnished, and a piece of land of sufficient extent cleared and planted, together with the necessary agricultural implements and a stock of provisions, will, it is calculated, cost the society a sum equal to $30 or $40 per head for each emigrant, allowing each family to consist of five persons. The cost of establishing families intending to follow trading and mechanical pursuits, will be somewhat less than the above estimate for agricultural families; but the average cost for the whole of the emigrants may be estimated at $50 per head, including all the expenses of transportation, making a total of from $400,000 to $600,000 per annum, _for the first two years_. As the colony increases in population, and the interior of the country becomes settled, any number of emigrants that may be sent out will be readily absorbed, as there will be a demand for all kinds of laborers, mechanics, and domestic servants, and it will be unnecessary to make that provision for them which is now indispensable. The Colonization Society will, as heretofore, so regulate the emigration as to send out only suitable persons, and keep up a due proportion between the two sexes. By the compact between the Colonization Society and the Republic, made when the society ceded its territory to the Republic, ample power is reserved by the society for the protection of emigrants who may be sent out by them. Moreover, the authorities invite emigration, and each emigrant receives a donation of a tract of land. The establishment of prosperous colonies on the western coast of Africa will, doubtless, tend greatly, in the course of time, to the augmentation of the commerce of this country. It appears that British commerce with Africa amounts to no less than 5 millions sterling, or about $25,000,000 per annum. The belief is now confidently entertained in Great Britain, that an immense commerce may be opened up with that continent, by putting an end to the slave trade, and stimulating the natives to the arts of peace. The commerce of Africa is certainly capable of great extension, and it is worthy of observation, that the proposed steamers will open entirely new sources of trade.