A full discussion of all the considerations, on one side or the other, of this question, would demand more space, and more of technical detail, than the scope of these papers permits. As with most conclusions of a concrete character dealing with contradictory elements, the result reached will inevitably be rather an approximation than an absolute demonstrable certainty; a broad general statement, not a narrow formula. All rules of War, which is not an exact science, but an art, have this characteristic. They do not tell one exactly how to do right, but they give warning when a step is being contemplated which the experience of ages asserts to be wrong. To an instructed mind they cry silently, "Despite all plausible arguments, this one element involved in that which you are thinking to do shows that in it you will go wrong." In the judgment of the writer, two conditions must be primarily considered in determining a class of battleship to which, for the sake of homogeneousness, most of the fleet should conform. Of these two, one must be given in general terms; the other can be stated with more precision. The chief requisite to be kept in view in the battleship is the offensive power of the fleet of which it is a member. The aggregate gun-power of the fleet remaining the same, the increase of its numbers, by limiting the size of the individual ships, tends, up to a certain point, to increase its offensive power; for war depends largely upon combination, and facility of combination increases with numbers. Numbers, therefore, mean increase of offensive power, other things remaining equal. I do not quote in defence of this position Nelson's saying, that "numbers only can annihilate," because in his day experience had determined a certain mean size of working battleship, and he probably meant merely that preponderant numbers of that type were necessary; but weight may justly be laid upon the fact that our forerunners had, under the test of experience, accepted a certain working mean, and had rejected those above and below that mean, save for exceptional uses.
The second requisite to be fulfilled in the battleship is known technically as coal endurance,--ability to steam a certain distance without recoaling, allowing in the calculation a reasonable margin of safety, as in all designs. This standard distance should be the greatest that separates two coaling places, as they exist in the scheme of fortified coaling ports which every naval nation should frame for itself. In our own case, such distance is that from Honolulu to Guam, in the Ladrones,--3,500 miles. The excellent results obtained from our vessels already in commission, embodying as they do the tentative experiences of other countries, as well as the reflective powers of our own designers, make it antecedently probable that 10,000 and 12,000 tons represent the extremes of normal displacement advantageous for the United States battleship. When this limit is exceeded, observation of foreign navies goes to show that the numbers of the fleet will be diminished and its aggregate gun-power not increased,--that is, ships of 15,000 tons actually have little more gun-power than those of 10,000. Both results are deviations from the ideal of the battle-fleet already given. In the United States Navy the tendency to huge ships needs to be particularly watched, for we have a tradition in their favor, inherited from the successes of our heavy frigates in the early years of this century. It must be recalled, therefore, that those ships were meant to act singly, but that long experience has shown that for fleet operations a mean of size gives greater aggregate efficiency, both in force and in precision of manoeuvre. In the battleship great speed also is distinctly secondary to offensive power and to coal endurance.