A demand having arisen in this country and the United States for a second edition of the late Jfr. Herbert C. Pyjes Submarine Warfare, the publishers asked me to underlie the revision of the book. The request came at a time whea I was otherwise much occupied, but it seemed undesirable that the public demand should go unsatisfied, ad thus the new edition appears. It was a delicate matter to revise the work of a dead writer, and the volume remains in plan, character, and scope what the author made it. Since the first edition appeared, the second chapter, on The Pluce of the Submarine in Warfare, had lost its mlue, and two new chapters take the place in the present edition. All the other chapters are retained. The text has been revised, not with the purpose of altering if in any any, but of removing matter which had lost interest, and of introducing some new facts. Nothing has been omitted that could be retained. Few subjects are so difficult to write about as submarine navigation.... --This text refers to an alternate Paperback edition.