Knowing that the library here keeps a file of paper ephemera found in books — notes and scraps left behind by past fellows, past students and faculty of Dropsie College, and past owners collections that were donated upon their deaths — I offered this carnival ticket to the librarian when I found it in a book on tenth-century Arabic poetics.
"Oh," he said. "That doesn't count for very much here."
He proceeded to explain that when the library had to catalogue a large collection that it had just acquired, they used a roll of tickets to keep track of which ones they had entered and which ones they hadn't. And since the tickets were already there and so conveniently and sequentially numbered, those became the accessioning and call numbers for those books. It's unorthodox, to be sure, but only became a problem when they realized they had more books than tickets. Unable to get a different colored roll, they bought a second one of orange tickets and instituted a series of additions and substitutions so that each book could have a ticket and still have its own unique number. Apparently, to really make good use of this collection, you have to understand the system of substitution. It seems like a weirder system of organizing books than most, though alphabetical order, as Borges pointed out, is no less weird, yielding a collection that, when fully and optimally organized, sees hippopotamuses next to Hippocrates.
I love finding bits of paper in library books; better yet is when they have a great, quaint, improbable story to go with them.