Captain Shelford, an expert on submarine escapes, has studied minutely such submarine disasters as K-6, Rucumilla, and Thetis, and has actually been on the scene to direct rescue operations in many of the cases. In simple language, he tells how the first tube escapes were effected, then how specially-built crane ships, the Momsen Lung, and the McCann diving bell were perfected to save men from the deep. The text is made even more understandable with clear diagrams of equipment and photographs. An excellent book to add to any sea collection.