On shipboard there must be shipshapeness; and that capacious, one-time popular Atlantic liner had undergone changes to prepare it for its mothering part, with platforms in place of the promenades where people had lounged during the voyage, and bombs in place of deck quoits and dining-saloons turned into workshops. Of course, one was shown the different sizes and types of bombs. Aviators exhibit them with the pride of a collector showing his porcelains. Every time they seem to me to have grown larger and more diabolical. Where will aerial progress end? Will the next war be fought by forces that dive and fly like fish and birds? “I’d like to drop that hundred-pounder onto a Zeppelin!” said one of the aviators. All the population of London would like to see him do it. Also Fritz, of the submarine, does not like to see the shadow of man’s wings above the water. Seaplanes and destroyers carry the imagination away from the fleet to another sphere of activity, which I had not the fortune to see. An aviator can see Fritz below a smooth surface; for he cannot travel much deeper than thirty or forty feet. He leaves a characteristic ripple and tell-tale bubbles of air and streaks of oil. When the planes have located him they can tell the hunters where to go. Sometimes it is known that a submarine is in a certain region; he is lost sight of and seen again; a squall may cover his track a second time, and the hunters, keeping touch with the planes by signals, course here and there on the lookout for another glimpse. Perhaps he escapes altogether. It is a tireless game of hide-and-seek, like that of gunnery at the front. Naval ingenuity has invented no end of methods and no end of experiments have been tried. Strictest kept of naval secrets, these. Fritz is not to be told what to avoid and what not to avoid. Very thin the skin of a submarine; very fragile and complicated its machinery. It does not take much of a shock to put it out of order or a large cargo of explosive to dent that skin beyond repair. It being in the nature of submarines to sink, how does the hunter know when he has struck a mortal blow? If oil and bubbles come up for sometime in one place, or if they come up with a rush, that is suggestive. Then, it does not require a nautical mind to realise that by casting about on the bottom with a grapnel you will learn if an object with the bulk and size of a submarine is there. Admirals accept no guesswork from the hunters about their exploits; they must bring the brush to prove the kill. With Admiral Crawford I went to see the submarine defences of a harbour. It reminded one of the old days of the drawbridge to the castle, when a friend rode freely in and an enemy might try to swim the moat and scale the walls if he pleased. “Take care! There is a tide here!” the coxswain was warned, lest the barge get into some of the troubles meant for Fritz. “A cunning fellow, Fritz. We must give him no openings.”