The coordinates will bring you to the library itself. The rest is up to you! Will you venture into the restricted section? Will you try the good, old fashioned "accio cache!" trick? Sorry to say that Hermione isn't here to help you with this one!
Bring your own quill!
**Cache is available when the library is open. See attached picture for their normal business hours.** Placed with the permission of the AMAZING library staff.