[Quix]

IIRC

there was a hole where the one foci was and a dot where the other one was.

Isn’t it the case that a ball sent across the dot would then fall in the hole at the other foci regardless of what direction it was shot from?

Seems like that’s the case in my fuzzy memory of it.

[Mad Dawg]

Isn’t it the case that a ball sent across the dot would then fall in the hole at the other foci regardless of what direction it was shot from?

That sounds right, but I think the only thing to do is for you to buy one and me to come out and assist you in research.