The story of the contest between our war-ships and their new enemy, the submarine, is the story of a most remarkable and successful adaptation. Of the six principal methods of defence used by our Navy at the end of the fourth year of war, three are old and three new; and it is a striking proof of the scientific ability of the Service, that the three old methods have been carefully reconsidered, and that, instead of abandoning them because, in their original use, they were apparently obsolete, our officers have turned them to even better account than the new inventions. The oldest device for the protection of war-ships against torpedoes--whether fired by torpedo-boats or submarines--is the net. Our older battle-ships, as everyone will remember, were fitted with a complete set of steel nets on both sides, and with long booms for hanging them out. These booms, when not in use, were lashed diagonally along the ship’s sides, like great stitches, and gave the typical vessels of the British Fleet a peculiar and decidedly smart appearance. Very smart, too, was the quickness and precision with which the order ‘Out torpedo nets!’ was executed; but--long before 1914--everyone was perfectly aware that the nets were practically as much out of date as masts and sails. They were so heavy, and hung so low in the water, that no ship could manœuvre in them, and even for a fleet at anchor they had ceased to be a trustworthy defence; for the Whitehead torpedo was now fitted with cutters which could shear a way through the steel meshes. Nets of the old type, therefore, have played no part in the present War--unless we are to believe the Turkish account of the sinking of the _Ocean_ in the Dardanelles, according to which the nets were out, and were not only useless as a protection, but dragged down some of our men when they might otherwise have escaped by swimming. But, because one type of net is obsolete, the British Navy has seen no reason to reject all nets as impracticable. It is not beyond imagination to conceive a net so light and large of mesh, that it will diminish by no more than one knot the speed of the ship which carries it, and will yet catch and deflect a torpedo in the act of passing through it. For it must be remembered that the real problem is not how to stop a torpedo in its full 30-knot career, but how to prevent it from striking the ship with its head at an angle not too fine for the detonator to be fired. A turn of the helm, or the mere wave from the cut-water of a fast ship, has often sent a torpedo running harmlessly away along the quarter. The net of the future may be found equally successful in catching the fish by its whiskers and turning it forward along the bow, where the same wave will drive it outwards from the ship’s course.