They probably also have most of the bookshelves on rails? The local uni library keeps their old books on a system like this, it&#x27;s really quite cool. The room can fit, say, 54 bookshelves tight-packed with no room to enter anywhere. So they put 52 shelves in on rails, and between each pair there is a wire going across. Disconnect a wire between two shelves, and all the shelves slide apart so you can enter where you opened the wire.