Complementary to these transformations in commerce, navigation, and travel by sea, have come improved methods of their defence. Modern naval science in all of its aspects has been developed. Glancing for a moment in retrospect at the long line of naval progress, one sees it pass from the ancient row-galleys, to the sailing ship of the early Modern Age, and from thence to the steamships of to-day. The motive power has changed from human muscle to wind, and from wind to steam. Placed beside the iron-clad battleships, the light, wooden frigates of the Revolution look almost as antiquated as the Greek galley with its figured prow. Smart, trim, beautiful vessels were the Revolutionary craft, but how small, simple, and crude they now appear. Indeed, a new type of poet, one who loves raw force first, and the picturesque afterwards, has risen to sing the glories of new navies and new seas. Other naval changes have been made, as significant as those in style of vessel and motive power. Ships of war now wear heavy coats-of-mail. The “great guns” and the “long guns” of the Revolution are neither great nor long beside modern cannon. A new type of sea officer has been trained to meet the new conditions of naval service. It would puzzle a modern officer to take a schooner from Boston to Plymouth, for his seamanship is now fitted to steamships. By over-study of modern armament, torpedo boats, and the latest naval manœuvres, his “weather eye” has lost something of its skill for reading in the skies the coming of storms or sunshine. Trim and immaculate in their uniforms, the American naval officers of to-day, who have entered the naval profession by the way of their technical studies at Annapolis, little resemble their hardy prototypes in the Continental navy, to whom clung the barnacles of their apprenticeship aboard merchantmen. Notwithstanding this revolution in naval science, a consideration of the conditions of the Continental naval service and of the naval policy of the Marine Committee has to-day a practical value for naval experts. Certain fundamental principles in naval science do not change. Captain Mahan, in his “Influence of Sea Power upon History,” has pointed out that, while naval tactics vary with the improvements in the motive power and armament of fleets, the basic principles of naval strategy do not. They are as enduring as the order of nature. For example, one cannot conceive that there will come a time when an inversion will be made of the strategic principle, that an enemy should be struck at his weak point. Captain Mahan even finds it worth while, for the benefit of his fellow-experts, to set forth with some detail the naval strategy of the Carthaginian wars.