For the same reason the study of the sea history of the past will be found instructive, by its illustration of the general principles of maritime war, notwithstanding the great changes that have been brought about in naval weapons by the scientific advances of the past half century, and by the introduction of steam as the motive power.
It is doubly necessary thus to study critically the history and experience of naval warfare in the days of sailing-ships, because while these will be found to afford lessons of present application and value, steam navies have as yet made no history which can be quoted as decisive in its teaching.

Of the one we have much experimental knowledge; of the other, practically none.

Hence theories about the naval warfare of the future are almost wholly presumptive; and although the attempt has been made to give them a more solid basis by dwelling upon the resemblance between fleets of steamships and fleets of galleys moved by oars, which have a long and well-known history, it will be well not to be carried away by this analogy until it has been thoroughly tested.

The resemblance is indeed far from superficial.

The feature which the steamer and the galley have in common is the ability to move in any direction independent of the wind.