Mary Pegg popped their head over the parapet saw what was going on and
said
Mary Pegg wrote:

[fx: thinks] So the water is meant to travel around the rim and
*then* enter the bowl? So the problem lies at the front?

Golly! A Flash animation that's actually useful! See he
http://home.howstuffworks.com/toilet1.htm

I have never dealt with a cistern like that (leftpondian ?)
there appears to be no siphon merely some sort of flap
valve controlling the flush.

--
yours S

Nihil curo de ista tua stulta superstitione