Railway circulations books were cheap paperback editions marketed through news vendors. They were precursors to paperback books and sold much as paperbacks are in airports now, though in smaller stands and with less elegant covers. They weren't sold only in railroad stations, but such vendors did a better busness in books than most news vendors because people wanted something to read on the train. Better Twain than the penny-dreadfuls also available. SLC did not like being the alternative to trash. Andy Hoffman