Marauder's Map

[Hillman, Lee]

No: HPFGUIDX 23527

There have been a lot of good topics opened up, and as usual I'll be chiming
in on some of them. This time I'll try to do it one by one.

I looked through PoA and GoF for references to the Marauder's Map, to see if
there's anything that might help resolve the question of how it includes
dots for so many people.

When F&G first give Harry the map, it's the Hogsmeade weekend before
Christmas break. All third-years and above are allowed to leave the school,
and most have done so. As we've seen at Halloween, those who choose not to
go for some reason and the second and first years tend to confine themselves
to their common rooms/dorms or the library. Hence, few people are actually
moving round the school. ("The Marauder's Map")

As for Pettigrew's appearance or lack thereof on the map, Ron is already
gone when Harry consults it on this occasion, and Scabbers disappears before
Harry uses it next. 

That would be the occasion of _another_ Hogsmeade weekend, again with few
people left in the school, and again, he meets Ron after Ron has left with
the group. So by the time Harry looks at the map, there aren't many people
on it. It is on this occasion that he gets caught by Snape and ultimately
loses the map to Lupin. ("Snape's Grudge")

Since Lupin has no need to sneak around, we can probably conclude that the
map stayed dormant or at least was not in constant use until the night of
the Shrieking Shack. Lupin explains specifically that he was "watching the
map carefully" because he had a feeling they would sneak out. Exams are over
at this point and again, it is evening and few students are outside their
common rooms. Here we learn that Hagrid's hut itself is not part of the map,
but the grounds between the castle, the hut, and the Willow are. We also can
infer that he only sees one Harry and one Hermione, though he doesn't
specifically state this. (Ch. 17-19)

At the end of the year, Harry gets the map back from Lupin, but they're
going home; no need to consult it again.

In GoF, Harry only uses the map once: to sneak to the Prefect's Bathroom and
home. Again, it's late at night, most of the castle is asleep. Here, though
the map is activated, Moody/Crouch captures it, sees his own name on a dot
standing where he is standing, and has excellent motivation to keep Harry
from regaining it. He tells Harry that Crouch is gone, which of course is a
lie. ("The Egg and the Eye")

We learn in "Veritaserum" from Crouch that he watched the map for over a
week, waiting for his father. However, when his father arrives, it is on the
edge of the forbidden forest. This also provides confirmation that the FF is
on the edges of the map (or else that the map adjusts itself to show only
those areas one wants to check--again, reading intention). He uses the map
to locate his father, and for all we know, never uses it again.

Now, there are some general observations that I think are reasonable given
all this information. One: Dumbledore and Snape now know about the Map; it's
no longer going to be much good to Harry, even if he somehow gets it back
(and as far as we know, he doesn't). Two: Nearly every time it is in use,
there are either few people in the castle itself or at least outside of
their common rooms and/or dormitories. When there might be (as Crouch's
vigil for his father), the person is looking outside the castle for some
reason. Furthermore, no structure other than the castle itself is mapped
inside. Nothing inside Hagrid's hut, no mention of the greenhouses, the
pitch, etc. 

This doesn't resolve every question about the map, still. How does it manage
to cram so much information onto a single piece of parchment? Perhaps it is
like the "maps" of dungeons in many computer adventure games, where the
screen only reveals the area immediately surrounding the player? If that is
so, though, how is it able to show a part of the castle or grounds where the
user is not standing? (Eg: Harry sees Snape in his office, but how far away
is that from the staircase where he got stuck?)

As for the twins not noticing, who says they used the map on any occasion
when Ron was not where he was supposed to be?

I think it truly does come down to intention. MWPP must have thought hard
about the kinds of things they were going to use the map to do, and they
chose the spells that would create the artefact. In the case of Hermione's
time-turner, I do not believe they ever anticipated having two of the same
person in the halls or on the grounds, so they did not use any spells that
detect time-altering devices. Likewise, I think they decided they didn't
need to know who was in the dorms or common rooms, because those people were
not a direct threat to any prank they wanted to pull for which they needed
access to the corridors. Therefore, the map is not ensorceled to show people
in their own common rooms or dorms. [Note: this part of the theory falls
down if they ever wanted to access the common rooms or dorms for the purpose
of pulling off a prank. But in the absence of evidence, one could reasonably
say they never crossed that line.] MWPP must also have known that a person
moving on the far side, three floors above, was of little threat to someone
on this side, three floors below, and may have specified the map's behaviour
to ignore such a person.

It's like a computer. It can only apply those programs which have been
entered into it. If the map comes into contact with something it doesn't
know how to interpret, it doesn't interpret.

I'm interested to know which spells were powerful enough to allow the map to
recognize students who were not enrolled during any part of MWPP's tenure as
students.


Gwendolyn Grace