Holland's boat, built in 1877, was the first to use a gas-engine as a propulsive medium, but it was not until the final adoption of the gas-engine for surface work, followed later by the internal-combustion gasoline-engine and the use of electric storage-battery for subsurface work, as well as the invention of the periscope and various other devices, that the submarine was developed to a present state of effectiveness, which sees it crossing the Atlantic from Germany, operating off our shores and returning to Germany without being obliged to put into port; which, also, sees it capable of navigating under water at a speed of from seven to nine knots, with torpedoes ready for use in the tubes and guns of effective caliber mounted on deck. It has, indeed, been asserted that the airplane and the submarine have relegated the battleship to the limbo of desuetude: but as to that the continued control of the seas by Great Britain with her immense battle-fleet, supplemented by our tremendous engines of war, certainly argues for no such theory. What the future may bring forth in the way of submarines, armored and of great size, no man may say. But at present the submarine, while tremendously effective, has not done away with the battleship as a mighty element in the theory of sea power. As to life on a submersible, let us construct from material which has come to us from various sources in the past three years a little story which will give a better knowledge of the workings of the German undersea boat than many pages of technical description would do. An undertaking of the sort will be the more valuable because we of the Allies are inclined to consider the submarine problem only in relation to our side of the case, whereas the fact is that the submarine operates under great difficulties and dangers, and in an ever-increasing degree leaves port never to be heard from again. We may, then, begin the following chapter with a scene in Kiel, Zeebrugge, or any German submarine base. CHAPTER VI On a German Submarine--Fight with a Destroyer--Periscope Hit--Record of the Submarine in this War--Dawning Failure of the Undersea Boat--Figures Issued by the British Admiralty--Proof of Decline--Our Navy's Part in this Achievement A first lieutenant with acting rank of commander takes the order in the gray dawn of a February day. The hulk of an old corvette with the Iron Cross of 1870 on her stubby foremast is his quarters in port, and on the corvette's deck he is presently saluted by his first engineer and the officer of the watch. On the pier the crew of the U-47-1/2 await him. At their feet the narrow gray submarine lies alongside, straining a little at her cables.