[Dragaera] Castle Black

[Jon Lincicum]

So...

Re-reading "Lord of Castle Black", I notice that Castle Black's continued levitation seems to depend on the ongoing efforts of Morrolan's Circle of Witches. At least, according to Paarfi, in the immediate aftermath of the Battle of Dzur Mountain, it does.

This strikes me as an extremely tenuous situation for a major structure inhabited by hundreds of individuals a half mile in the air. 

What if there were an epidemic? Or some bozo with a Great Weapon broke in and slaughtered all the witches? Or if the tower where the witches were gathered collapsed? 

Would the whole castle suddenly fall out of the sky? Or has the levitation perhaps been made more permanent in some fashion? 

It also seems a lot to ask of a witch to have to spend 8-10 hours a day, 5 days a week, sitting in a circle with 16 other witches chanting. Do they ever get any time off? Wouldn't this get rather tiresome after two and a half centuries? (Especially for Easterners?)

Any thoughts?

Majikjon