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A must have for steam traction engine enthusiasts. Not only is this a useful reference for determining what engine you may be seeing in a picture or at a show, but also a history of the companies. In a lot of ways those histories determined a lot of the design practice of the various steam tractor manufacturers. While not a completely exhaustive list of every steam tractor manufactured and all of the various changes, this book does attempt to cover all of the major manufacturers as well as multiple minor manufacturers. The manufacturer information along with images of their products can help point someone in the right direction for more in depth research.