During any scientific, research, or subject matter exploration, understanding the finer details can make or break a project. Observations that seem like minutia can be key puzzle pieces. In the Sno-Train image below, you can just make out a 4th trailer attached to the convoy. If you look closely, you can make out, what appear to be a spoked rim. This trailer is NOT a LeTourneau trailer. I will dedicate an entire chapter in my book to what these trailers and wheels originated and who built them. Until then, enjoy this newly published image.
