Well Douglas, I'm no dummy, I knew exactly what you wanted to know. The book is, quoting from the title page, "A sketch of their (narrow gauge railways) rise, progress, and sucess: valuable statistics as to grades, curves, weight of rail, locomotives, cars, etc." The 1949 reprint also includes a directory of all(?) narrow gauge railways in North America from 1871 to 1949. In other words it is the same basic concept as Proffesor George Hilton's book: "American Narrow Gauge Railroads", but without the chapters on failure and decline. I hope this helps.
Regards,
Don F.