This is quite an old book; it was published originally in 1938 and generally unavailable until this paperback reprint in 2013 except in libraries. This is a facsimile reprint of the original edition; there is not even an introduction of more recent vintage that places the book in the larger context of historical study.
The book itself is a leisurely discussion of marine vehicles from the beginning of the steamship age to the point at which the book was published just before World War II. It begins with several chapters on steamships and the propulsion systems used on those vessels. This includes commentary on commercial and military vessels, innovations in the propulsion systems, screws, navigation, speed, armoring and armaments, and the like. Considerable analysis of the boiler systems for steamships follows, along with related and ancillary machinery. At the narrative moves into the twentieth century Edgar Smith turns attention to other types of propulsion systems, especially the varieties of coal versus oil burning engines.
This is a highly technical study based on journal articles, technical materials, and a few personal papers and unpublished materials. There are numerous schematics and illustrations of how the machinery associated with these vessels operated. At a technical level this is a treasure trove of information. As a work of history this is very much history as an engineer envisions it. There is little in the way on insight about how technology evolves; there is even less about the individuals who made the technology real and their process of invention. On the other hand, if one were restoring an old steamboat this would be an exceptionally valuable work. It explains exceptionally how these technologies worked.