During the last session of Congress a treaty for the annexation of the Republic of San Domingo to the United States failed to receive the requisite two-thirds vote of the Senate. I was thoroughly convinced then that the best interests of this country, commercially and materially, demanded its ratification. Time has only confirmed me in this view. I now firmly believe that the moment it is known that the United States have entirely abandoned the project of accepting as a part of its territory the island of San Domingo a free port will be negotiated for by European nations in the Bay of Samana. A large commercial city will spring up, to which we will be tributary without receiving corresponding benefits, and then will be seen the folly of our rejecting so great a prize. The Government of San Domingo has voluntarily sought this annexation. It is a weak power, numbering probably less than 120,000 souls, and yet possessing one of the richest territories under the sun, capable of supporting a population of 10,000,000 people in luxury. The people of San Domingo are not capable of maintaining themselves in their present condition, and must look for outside support. They yearn for the protection of our free institutions and laws, our progress and civilization. Shall we refuse them? The acquisition of San Domingo is desirable because of its geographical position. It commands the entrance to the Caribbean Sea and the Isthmus transit of commerce. It possesses the richest soil, best and most capacious harbors, most salubrious climate, and the most valuable products of the forests, mine, and soil of any of the West India Islands. Its possession by us will in a few years build up a coastwise commerce of immense magnitude, which will go far toward restoring to us our lost merchant marine. It will give to us those articles which we consume so largely and do not produce, thus equalizing our exports and imports. In case of foreign war it will give us command of all the islands referred to, and thus prevent an enemy from ever again possessing himself of rendezvous upon our very coast. At present our coast trade between the States bordering on the Atlantic and those bordering on the Gulf of Mexico is cut into by the Bahamas and the Antilies. Twice we must, as it were, pass through foreign countries to get by sea from Georgia to the west coast of Florida. San Domingo, with a stable government, under which her immense resources can be developed, will give remunerative wages to tens of thousands of laborers not now upon the island. This labor will take advantage of every available means of transportation to abandon the adjacent islands and seek the blessings of freedom and its sequence--each inhabitant receiving the reward of his own labor. Porto Rico and Cuba will have to abolish slavery, as a measure of self-preservation, to retain their laborers.