“But, if he really commands, he must know enough about the instruments that do his work to know when they are doing it well and when not; to know whether his subordinates immediately in charge of the several devices are operating them properly or not; to know when defects exist and when they have been made good. If he does not know or cannot learn these things, he must depend wholly on subordinates immediately in charge; and their reports will be law to him, or if not law, at least decisions from which he has no appeal. Manifestly such a situation is utterly incompatible with the independent and self-relying autocracy which is the essential and fundamental principle of naval command, without which discipline must sooner or later vanish into mere empty form or conventional myth. These facts, even more than any other considerations, argue for uniformity of type, previously touched upon, so that in learning the traits of one battleship the officer acquires experience and knowledge applicable at once to the discharge of his duties in another. “The foregoing discussion is limited to matters affecting the unit of action, the single ship, and the captain. Passing to consideration of the unit of operation, the fleet and the admiral, we find another array of problems equally within the scope of this paper. “Let us assume that the composition of the fleet has been made as nearly homogeneous as possible, by carrying out the principles previously stated for ships and their captains, and that the admiral finds himself in command of an ideal fleet as to material and _personnel_. Actual differences in efficiency among the several units of action will still remain, and it will become the first duty of the admiral to ascertain and locate these diversities with unerring judgment and unsparing perception. He should know to a nicety the personal equation of every captain and the effective individuality of every ship. “Among the captains he should be able to differentiate the traits of relative quickness of perception, promptness of action, readiness of responsibility, and boldness of execution.”