On May 23, 1939, the U.S. submarine Squalus sank for unexplained reasons off the New England coast. Up to that time, a number of submarines had gone down and men had been left to die because there was no way of salvaging them. Annapolis graduate Charles Bowers Momsen was particularly sensitive to the tragedies (he'd lost some of his friends on the bottom) and with a single-mindedness which won him a good many higher-up raised eyebrows, Momsen designed the ""Momsen lung"" which became standard escape equipment for all submarines. He went on to create a ""bell."" Spliced into the rescue story of the Squalus when the ""bell"" was first used successfully, are the ups and downs of Momsen's experiments, the tension endured by the wives of those aboard the downed Squalus, and the feelings of the men themselves. The writing is substantially good although there are times when one suspects that the book is something of a stretcher, might have been a better article.