The returns chute reads each book's chip, checks it against the catalogue, and drops it in the bin for its shelf. Once a week something comes down the chute with a chip in our format, a number the catalogue does not hold, and the sorter sends it to bin 9, which is the bin for a floor we do not have.
I manage the automated returns for a central library, which is a machine most people have never seen and everybody uses.
How it works.
You put a book through the slot in the wall. A reader picks up the chip in its cover, the system looks the item up, marks it returned with a timestamp, and the sorter drops it onto a belt and into one of eight bins, one per floor or department. Staff empty the bins and shelve.
An item the system does not recognise goes to the exception bin, which is bin 1, and somebody looks at it in the morning. That is where the books from other libraries go, and the DVDs somebody has muddled with a book, and the occasional shoe.
There is no bin 9. The sorter has eight.
About once a week the log shows an item returned at night, between two and four, with a chip number in our format and not in our catalogue, sorted to bin 9.
The building is shut. The slot in the wall is open all night by design, but it is on a camera and the camera shows nobody at it.
In the morning there is a book in bin 8.
Bin 8 is the last bin on the belt and the belt, told to go to a ninth, runs to the end and drops whatever it is carrying where the belt stops. So the book lands in 8 with the local history returns, and the staff who empty 8 find one that is not ours.
What the books are.
Ordinary books. Hardbacks, mostly, older, library bound in the buckram that every library used until about 1990, with a chip in the cover that reads in our format and with a spine label in our classification.
They are not in our catalogue, and they are not in any catalogue I can search, which is most of the country's. The titles are real enough to read on the spine and not real enough to exist: a county history for a county that does not have that name, a manual for a trade I cannot identify, a novel by an author no database has heard of.
I have a shelf of them in my office. Thirty one.
What has been checked.
The sorter, which is a belt and some flaps and a controller, serviced by the people who made it. Their engineer confirmed it received a sort instruction for bin 9 from our system, which is the instruction it acted on. Our system has no bin 9 configured and cannot, he says, issue one.
The chips. I have read them with a handheld. They carry an item number in our format, a branch code that is not one of our branches, and a security bit set the way ours are set.
The camera on the slot, which records on motion and has recorded a fox, a drunk, and two people returning books at three in the morning who were exactly who they looked like. On the nights a bin 9 book arrives it records nothing, and the slot's own sensor, which counts items passing it, counts one.
The thing I read in one of them.
I do not open them, as a rule. They are catalogued as unidentified stock and they sit on the shelf.
I opened one in 2022 because it was the county history and I wanted to know which county. The frontispiece is a map. It is this county, with the towns where they are and the rivers where they are, and the names are all wrong, every one of them, in a way that made me put it back on the shelf and go and do something else for the rest of the afternoon.
What is done about it.
They are stock. Unidentified stock is a category, and the thirty one are on a shelf in my office with a spreadsheet, and the auditor has seen the spreadsheet and asked whether we had tried to return them to their library and I said we had not been able to identify it.
What I do.
I run the sorter and I empty bin 8 myself on the mornings the log shows a bin 9.
The one change is that the book does not stay in the building overnight.
It comes off the belt, it goes on my shelf, and the shelf is in my office, and my office is on the second floor, and the returns room is in the basement.
The first one I found, in 2021, I left on the returns room desk overnight to deal with in the morning. In the morning it was on the belt, at the far end, in the position it lands in when the sorter runs to the end, and the sorter's log showed it returned again at ten past three, sorted to bin 9, and the slot's counter had counted one, and the book had been in a locked room the whole time, forty feet from the slot.