What, then, can be done? Must we rest content in all situations with Howe's system, which riper experience condemned for cases of extreme necessity? Cannot the old close blockade be given a modern form? Assuredly it can. In old days the shoreward limit of the blockading fleet was just beyond the range of the coast batteries, and this position it held continuously by means of an inshore squadron. In these days of mobile defence that limit is by analogy the night range of destroyers and the day range of submarines, that is, half the distance they can traverse between dark and dawn or dawn and dark respectively, unless within that limit a torpedo-proof base can be established. A blockade of this nature will correspond in principle to a close blockade of the old type; nor in practice, as was proved in the Japanese blockade of Port Arthur, will its incidents be materially different. The distance at which the battle-squadron must keep will seem at first sight to deny it certainty of immediate contact--the essence of close blockade. But in truth other new factors already noticed will reduce that distance relatively. Quicker and more certain means of communication between the admiral and his scouts, the absolute freedom of movement and the power of delaying the enemy's actual exit by mining, may go far to bring things back to their old relations. At Port Arthur they did so entirely. If then, as in that case, our paramount object is to keep the enemy in, there seems still no reason why we should not make our dispositions on the principle of close blockade. Distances will be greater, but that is all. Nor must it be forgotten that for a squadron to take station off a port in the old manner is not the only means of close blockade. It may still effect its purpose, at least temporarily, by supporting mining vessels or block ships--"sinkers," as they used to be called. The latter expedient, it is true, had little success in the latest experiments, but even in the Russo-Japanese War its possibilities were by no means exhausted. We have therefore to conclude that where the strategical conditions call obviously for close blockade, our plan of operations will be modified in that direction with the means still at our disposal.