He stated further: "If we go to war with a country that is within striking distance of submarines, I am of the opinion that the country will at once lock up their dreadnoughts in some safe harbor and we shall do the same. I do not think the importance of submarines has been fully recognized, neither do I think that it has been realized how completely their advent has revolutionized naval warfare. In my opinion, as the motor has driven the horse from the road, so the submarine has driven the battleship from the sea." Sir Percy Scott, however, is an inventor, being the man who devised the "spot" method of gun firing, and has, therefore, the type of mind which is able to foresee and to grasp the value of new devices. Sir A. Conan Doyle, another man of great vision and imagination, was so impressed with the potentialities of the submarine that he wrote a story which prophesied, with such accuracy as to make his tale almost uncanny, the events which are actually taking place to-day around the coast of England in the prosecution of Germany's submarine blockade. In these pages, therefore, I may make claims for submarines which have not yet been publicly proved by actual performance, and such claims may impress many as being as visionary as the destructive capabilities of submarines appeared to be until Lieutenant Weddingen, of the German Navy, shocked the conservatives and put the submarine on the map as a naval weapon by sinking, single-handed, three cruisers within one hour of each other. I shall be careful, however, not to make any claim for submarines which is not warranted by experiments actually made during my twenty-two years' continual study and experience in designing and building submarine boats and submarine appliances in the United States and abroad. To men of imagination and of inventive faculties these claims will not appear preposterous. The achievements of the submarine, in the face of all the ridicule, scepticism, and opposition which surrounded its development, will, I hope, commend these advanced ideas of mine to the attention, if not the respect, of the more conservative. CHAPTER I WHAT THE MODERN SUBMARINE IS What is a modern submarine boat? A modern submarine vessel is a complex mechanism capable of being navigated on the surface of the water just as is any boat, but with the added faculty of disappearing at will beneath the surface, and of being operated beneath the surface in any desired direction at any desired depth. Some submarines are able to wheel along the bottom itself, and are also provided with diving compartments from which members of the crew, encased in diving suits, may readily leave and re-enter the vessel during its submergence.