Detecting Spells (was Re: Underage magic?)

[Sharon]

Anne said, in regards to the MoM detecting magic:
As for the magic Riddle did on Morfin, all of that occured within a
known magical household.
> 

Judy said:
True, but only one person lived in it, so having Stunning or Memory 
Modification spells going on was odd.  For that matter, Stunning and 
Memory Modification are the sorts of things one would think the MoM 
would want to keep an eye on in general (along with AK and so 
forth.)  This is one of the reasons why I tend to think the Ministry 
doesn't have the resources to monitor magic in general, and just spot-
checks.
>



My turn, again:

I sort of wonder that the Ministry doesn't look at the spells 
themselves - at least, not initially - and only at where magic is 
being done.  It's only when magic is done in an odd location, such as 
the home of a Muggle, that they look into what spell was actually 
performed.  (Explaining why the Ministry knew it was a Hover Charm 
performed at Privet Drive.)

Thus, the Ministry would have only detected magic at the Gaunt 
household, and as it was the home of a wizard, there was no need to 
see what sort of spell he cast.

I would also think that detection of a specific type of spell would 
be a much more difficult system than a general one that simply alerts 
to magic being performed in certain locations.  The Ministry would 
not want to waste manpower on such an operation which surely would 
take up a great deal of time and effort to maintain and operate.

--sharon, who is aware that the previous paragraph makes no sense, 
but is too distracted by her pistachios to bother correcting it