Wand question

[quigonginger]

No: HPFGUIDX 130481

I'm having a Star Wars weekend with my 9-year-old Godson, and out of 
no where, whilst playing with my CoS Lego set, he asked me "how do 
they know which end the magic comes out of?"  

I had never thought of this before.  I would assume a wand can be held 
backwards, and that pointing a wand the wrong way would cast the curse 
in the opposite direction.  Are they tapered (like a conductor's 
baton) or do they have a definite "handle"?  Do they just feel it? 

Any thoughts?  Now he's got me curious.

Ginger, trying to talk Star Wars and Harry Potter at the same time 
with a kid who changes subjects at the drop of a hat and always uses 
pronouns without antecedents.