Well, I've mentioned the book more than once so maybe I should throw it in here.
This heavy book was an effort by the late Russel H. Beatie to cover, in a single volume, the entire topic. The book sets out a history of the saddle, and some saddle parts, such as stirrups. The book also discusses saddling, selecting a saddle, and the mechanics of riding.
As most would suspect, a book attempting to take on this entire topic is unlikely to be a complete success. As comments on the main forum indicate, this book falls short in a lot of areas. At least some, and some would say a fair amount, of the information is inaccurate. This is particularly so in the section dealing with military saddles, which refers the reader to Steffens, and borrows some of his depictions. If you wanted to learn about military saddles, this book would be a poor place to start.
Having said all that, this book does have some value to a person who wants a general knowledge of the western saddle. It is really a general starting place, with some good content, and some interesting photographs (others are reprints from other publications or manufacturers). Reading it will either wet the readers appetite, or bore them into another topic.
Pat