The portion of the naval force of the Union in actual service has been chiefly employed on three stations--the Mediterranean, the coasts of South America bordering on the Pacific Ocean, and the West Indies. An occasional cruiser has been sent to range along the African shores most polluted by the traffic of slaves; one armed vessel has been stationed on the coast of our eastern boundary, to cruise along the fishing grounds in Hudsons Bay and on the coast of Labrador, and the first service of a new frigate has been performed in restoring to his native soil and domestic enjoyments the veteran hero whose youthful blood and treasure had freely flowed in the cause of our country's independence, and whose whole life has been a series of services and sacrifices to the improvement of his fellow men.

The visit of General Lafayette, alike honorable to himself and to our country, closed, as it had commenced, with the most affecting testimonials of devoted attachment on his part, and of unbounded gratitude of this people to him in return. It will form here-after a pleasing incident in the annals of our Union, giving to real history the intense interest of romance and signally marking the unpurchasable tribute of a great nation's social affections to the disinterested champion of the liberties of human-kind.

The constant maintenance of a small squadron in the Mediterranean is a necessary substitute for the humiliating alternative of paying tribute for the security of our commerce in that sea, and for a precarious peace, at the mercy of every caprice of four Barbary States, by whom it was liable to be violated. An additional motive for keeping a respectable force stationed there at this time is found in the maritime war raging between the Greeks and the Turks, and in which the neutral navigation of this Union is always in danger of outrage and depredation. A few instances have occurred of such depredations upon our merchant vessels by privateers or pirates wearing the Grecian flag, but without real authority from the Greek or any other Government. The heroic struggles of the Greeks themselves, in which our warmest sympathies as free men and Christians have been engaged, have continued to be maintained with vicissitudes of success adverse and favorable.

Similar motives have rendered expedient the keeping of a like force on the coasts of Peru and Chile on the Pacific. The irregular and convulsive character of the war upon the shores has been extended to the conflicts upon the ocean. An active warfare has been kept up for years with alternate success, though generally to the advantage of the American patriots. But their naval forces have not always been under the control of their own Governments. Blockades, unjustifiable upon any acknowledged principles of international law, have been proclaimed by officers in command, and though disavowed by the supreme authorities, the protection of our own commerce against them has been made cause of complaint and erroneous imputations against some of the most gallant officers of our Navy. Complaints equally groundless have been made by the commanders of the Spanish royal forces in those seas; but the most effective protection to our commerce has been the flag and the firmness of our own commanding officers.

The cessation of the war by the complete triumph of the patriot cause has removed, it is hoped, all cause of dissension with one party and all vestige of force of the other. But an unsettled coast of many degrees of latitude forming a part of our own territory and a flourishing commerce and fishery extending to the islands of the Pacific and to China still require that the protecting power of the Union should be displayed under its flag as well upon the ocean as upon the land.

The objects of the West India Squadron have been to carry into execution the laws for the suppression of the African slave trade; for the protection of our commerce against vessels of piratical character, though bearing commissions from either of the belligerent parties; for its protection against open and unequivocal pirates. These objects during the present year have been accomplished more effectually than at any former period. The African slave trade has long been excluded from the use of our flag, and if some few citizens of our country have continued to set the laws of the Union as well as those of nature and humanity at defiance by persevering in that abominable traffic, it has been only by sheltering themselves under the banners of other nations less earnest for the total extinction of the trade of ours.

The active, persevering, and unremitted energy of Captain Warrington and of the officers and men under his command on that trying and perilous service have been crowned with signal success, and are entitled to the approbation of their country. But experience has shown that not even a temporary suspension or relaxation from assiduity can be indulged on that station without reproducing piracy and murder in all their horrors; nor is it probably that for years to come our immensely valuable commerce in those seas can navigate in security without the steady continuance of an armed force devoted to its protection.

It were, indeed, a vain and dangerous illusion to believe that in the present or probable condition of human society a commerce so extensive and so rich as ours could exist and be pursued in safety without the continual support of a military marine--the only arm by which the power of this Confederacy can be estimated or felt by foreign nations, and the only standing military force which can never be dangerous to our own liberties at home. A permanent naval peace establishment, therefore, adapted to our present condition, and adaptable to that gigantic growth with which the nation is advancing in its career, is among the subjects which have already occupied the foresight of the last Congress, and which will deserve your serious deliberations. Our Navy, commenced at an early period of our present political organization upon a scale commensurate with the incipient energies, the scanty resources, and the comparative indigence of our infancy, was even then found adequate to cope with all the powers of Barbary, save the first, and with one of the principle maritime powers of Europe.

At a period of further advancement, but with little accession of strength, it not only sustained with honor the most unequal of conflicts, but covered itself and our country with unfading glory. But it is only since the close of the late war that by the numbers and force of the ships of which it was composed it could deserve the name of a navy. Yet it retains nearly the same organization as when it consisted only of five frigates. The rules and regulations by which it is governed earnestly call for revision, and the want of a naval school of instruction, corresponding with the Military Academy at West Point, for the formation of scientific and accomplished officers, is felt with daily increasing aggravation.

The act of Congress of May 26th, 1824, authorizing an examination and survey of the harbor of Charleston, in South Carolina, of St. Marys, in Georgia, and of the coast of Florida, and for other purposes, has been executed so far as the appropriation would admit. Those of the 3d of March last, authorizing the establishment of a navy yard and depot on the coast of Florida, in the Gulf of Mexico, and authorizing the building of ten sloops of war, and for other purposes, are in the course of execution, for the particulars of which and other objects connected with this Department I refer to the report of the Secretary of the Navy, herewith communicated.