Amongst the great and important changes to be brought about in war by steam, we must look forward to its facilitating, by the certainty and rapidity of the movements of those destined to accomplish the objects in view, the protection, or destruction of much property, both public and private; also to its occasioning, for the same reasons, vast suffering to the inhabitants of the countries fixed upon, for whatever cause, to become the theatres of these awful and devastating operations. I cannot exactly compare them, and their consequences, to the unlooked for descents of the sea-kings of old, yet they must greatly, I fear, resemble them in their destructive and other effects, and they must be felt ere long all over the world. We were, as a nation, allowed by Providence, no doubt for wise purposes, to live so long in, I fear, not duly valued tranquillity and security, under the protection of our splendid navy of former days, that those who remained at home really knew nothing of war, and its attendant trials and privations, but the name. Long may this be the case, and this happy state, when compared with that of other countries, may, in all human probability, be rendered more lasting, if we will only be wise enough to take timely lessons from the past. History tells us of the rapid fall of many once powerful nations--how they fell it is not for me to relate; but Spain, her former greatness, and the causes of her present debasement, should be constantly before our eyes. We are still a great and warlike people, but I trust that we may be enabled to act with judgment, and to take, at all events, such steps as will prevent any other nation from anticipating us in the use of steam for warlike purposes. Those who have already deeply considered the subject, have come to the conclusion, that a comparatively small, but well constructed, and powerfully propelled steamer, alike overcoming wind and tide; capable of taking up and retaining a position within a certain distance of the largest sailing vessel, may be supposed able to destroy or capture her, however brave or excellent her officers and crew may be, and it is concluded, that this could probably be accomplished with but very little loss or damage, being sustained by the steamer, if judiciously manœuvred, and her commander would besides possess the great advantage, of going into action or not, as he might think most advisable. The old naval tactics, such as that of ships gaining what is termed the weather gage of each other, or any thing of that kind, in going into action, must be wholely abandoned whenever a steamer heaves in sight; for the sailing vessel is at once supposed to be, in a great measure, at her mercy.