Since then there has been considerable dissemination of facts about the submarine; much of this knowledge has found its way into print, some in short historical sketches published by the author and other designers. However, most of the publications on this subject have come from the hands of professional writers and newspaper men, some of whom have not had the engineering knowledge to sift the practical from the impractical, and who have not had any actual first-hand acquaintance with the facts. They have not understood the mechanical details of the submarine and the principles governing its operation well enough to comprehend or to elucidate the various phases of the development of this type of vessel. The result has been that many inaccuracies have been published, both in respect to the history of the development of the submarine and in regard to the practical operation of such vessels. There have been published one or two good works dealing with this subject in a very complete and intelligible manner, but intended for those engaged in engineering pursuits. One of the best of these was "The Evolution of the Submarine Boat, Mine and Torpedo, from the Sixteenth Century to the Present Time," by Commander Murray F. Sueter, of the Royal British Navy, published in 1907. When this book first appeared the present writer felt that the subject had been so fully covered that there was no need for him to publish his own information. However, since the beginning of the world-war the prominent part played by the submarine has led to a demand for more knowledge about the workings of this weapon of mystery, and for information concerning its future possibilities. The aim of this work, therefore, is to present to the reader in a simple, interesting way the facts relating to the submarine; its mechanical principles; the history of its development; its actual operation; the difficulty of combating it; and its industrial possibilities. These facts are presented, together with descriptions of the experience of the author and other inventors, in order to clarify in the reader's mind the difficulties, the trials and tribulations of both the submarine operator and the inventor. Furthermore, the narrative is not restricted to a discussion of the submarine question from a mechanical standpoint. The submarine to-day is a factor in the political and industrial life of the world. The submarine problem transcends a mere matter of mechanical detail, and a book upon this topic must, of necessity, deal with it in its broadest aspects. SIMON LAKE CONTENTS CHAPTER PAGE I. WHAT THE MODERN SUBMARINE IS 6 II. COMEDY AND TRAGEDY IN SUBMARINE DEVELOPMENT 36 III. EXPERIENCES OF PIONEER INVENTORS OF THE SUBMARINE 77 IV. THE EVOLUTION OF THE SUBMARINE 149 V. USE OF THE SUBMARINE IN WAR 196