SPECIAL NOTE: THE SECOND STAGE OF THIS CACHE IS UNAVAILABLE WHILE THE LIBRARY IS CLOSED. However, as soon as the library reopens you will be able to resume.
Where does Hermione Granger spend all her spare time? The GPS coordinates to Stage 1 will bring you to a not-very-helpful sign. You need the clue hidden there to continue to the final stage.
The coordinates for the final stage will get you to the front door. But once in the building you will need the clue from stage 1.
BTW, this cache is only available during open hours, and it is placed with permission.