The squadron, as assumed, requires about 11,500 tons of coal every five weeks in peace time. Some is commonly obtained from contractors at foreign ports; but to avoid complicating the subject we may leave contract issues out of consideration. If you keep a stock of 10,000 tons at your permanent secondary base, you will have enough to last your ships about four-and-a-half weeks. Consequently you must have a stream of colliers running to the place so as to arrive at intervals of not more than about thirty days. Calculations founded on the experience of manoeuvres show that in war time ships would require nearly three times the quantity used in peace. It follows that, if you trebled your stock of coal at the base and made it 30,000 tons, you would in war still require colliers carrying that amount to arrive about every four weeks. Picture the line of communications with the necessary colliers on it, and see to what extent you are released from the necessity of defending it. The bulk of other stores being much less than that of coal, you could, no doubt, maintain a sufficient stock of them to last through the probable duration of the war; but, as you must keep your communications open to ensure the arrival of your coal, it would be as easy for the other stores to reach you as it would be for the coal itself. Why oblige yourself to use articles kept long in store when much fresher ones could be obtained? Therefore the maintenance of store depots at a secondary base no more releases you from the necessity of guarding your communications than it permits freedom of movement to your ships. The secondary base in time of war is conditioned as follows. If the enemy's sphere of activity is distant from the base which you have equipped with store-houses and fortifications, the place cannot be of any use to you. It can, and probably will, be a cause of additional anxiety to you, because the communications of its garrison must still be kept open. If it is used, freedom of movement for the ships must be given up, because they cannot go so far from it as to be obliged to consume a considerable fraction of their coal in reaching it and returning to their station. The line along which your colliers proceed to it must be effectively guarded. Contrast this with the system of direct supply to the ships-of-war. You choose for your flying base a position which will be as near to the enemy's sphere of action as you choose to make it. You can change its position in accordance with circumstances. If you cease to use the position first chosen you need trouble yourself no more about its special communications. You leave nothing at it which will make it worth the enemy's while to try a dash at it. The power of changing the flying base from one place to another gives almost perfect freedom of movement to the fighting ships. Moreover, the defence of the line communicating with the position selected is not more difficult than that of the line to a fixed base.