A hand-blown, double-walled glass sphere from a Bohemian workshop, silvered inside in the old mercury-glass way. It shows the room back slightly wrong, and folklore says the seeing begins there.
At a glance
Hang it in a window at dusk and watch the room appear inside it, curved and silvered and not quite right. This is a witch ball in the older sense: a hand-blown glass sphere about ten centimeters (four inches) across…