prior incantato/priori incantatem & Sirius' wand

[meglet2]

No: HPFGUIDX 35870

This relates to the discussion of the possibility that Sirius' 
innocence could have been proved by forcing his wand to reveal the 
last spell performed as is done through 'prior incantato' on Harry's 
wand after the Quidditch World Cup. When someone queried that on the 
basis of Dumbledore's description of priori incantatem as something 
extremely rare and the involuntary effect of two wands sharing the 
same magical core it was pointed out that these seem to be two 
different matters. Prior incantato is definitely a spell (it is even 
called simple by Fudge) whereas priori incantatem is more of a 
curious effect - Dumbledore or Sirius (can't remember which and 
haven't got GoF to hand at the moment) call it the reverse spell 
effect. It is certainly not in the control of the wizard and if it 
depends on the wands being 'brothers' it would not be of general use. 
But I am a bit confused by all this. My Latin is very rusty and never 
was that good but these just look to me like declension differences. 
Is incantato/incantatem a noun or verb. If noun in which case; 
incantato looks like a dative or ablative to me and incantatem an 
accusative. What is the relationship to prior or priori? That also 
looks like a matter of declension to me. I sort of vaguely related it 
to the phrase a priori (which is ablataive case, right?) but then 
realised I wasn't quite sure in what way that was used. Are there any 
Latin scholars out there who could define why JKR used these two 
different forms for the two instances mentioned and if they could 
therefore be two separate things? Or did she get confused herself and 
make a mistake in specifying such particular circumstances for priori 
incantatem?

On the slightly different matter of Sirius' lost wand, it is quite 
right that he 'borrowed' wands in the Shrieking Shack. But in that 
case I wonder how he was planning to kill Peter before getting access 
to a wand. Strangling him with his his bare hands? It seemed more 
accidental than planned that he had a few wizards around with wands 
when he finally cornered Peter? Or if Crookshanks had managed to get 
Peter to Sirius as a rat, was he going to keep form as Padfoot and 
eat him? (He lives on rats while hiding out in the cave in GoF) 
Though come to think of it that would not have worked as he would at 
least have needed Peter's body to prove his innocence. Has Sirius 
managed to get hold of a wand even by GoF? He will surely need one to 
take his full magical part in the fight to come. Presumably now he is 
going to be lying low with Lupin, Remus can acquire one for him. 
Although if the wand chooses the wizard sending someone else to buy 
one for you would be less than ideal. How in that case could Sirius 
get a wand? Do you think there might be black market dealers in wands 
in the WW who will supply wands to shady characters no questions 
asked? Is it heresy to think JKR might not have fully thought out 
some of these complications. She really had better get the next book 
out before sheer frustration at the delay has us all analysing the 
thing to bits.

Mercia