So how does a siphon really work?

[Pugilistic Animus]

simple derivation

P =F/A and F=mg,....the mass of the column of liquid is ρ*Volume and
Volume = Ah

so, F =mg =ρAgh then pressure at the base of the column = F/A =ρAgh/A = ρgh

[cwatters]

The Physicist was Stephen Hughes. One of his papers is here...

http://eprints.qut.edu.au/31098/8/31098a.pdf

Some of it was a total surprise to me. Here is an extract...

Another seeming ubiquitous misconception is that the maximum height of a siphon is dependent on atmospheric pressure. The maximum height of a water siphon actually depends on the tensile strength of water – i.e. the maximum weight that hydrogen bonds are able to support.

[Mr Optimistic]

I suppose

you realise that without an atmosphere you wouldn't have liquid water and without gravity you wouldn't have pressure (because there would be no atmosphere ).

[james ozzie]

Humblest apologies (grovel etc etc)

Oh dear oh dear, I seem to be guilty of the most unthinkable discourtesy to our serious readers! My humblest apologies to Barstow and the clever boy who does the Big Red Letters!

Yes, as was pointed out in the beginning, this could have been posted elsewhere. But isn't it surprising that some are able to find the time and inclination to flame me for it? Perhaps they can ask a moderator to delete it if it is so offensive?

But I am heartened by the more cerebral posters out there who have made thoughtful contributions.

And Barstow, perhaps you could add this to your collection of maxims:

"University degrees are only important to those who don't have one"

(Yeah, yeah, been there, done that, 4 years too...)

[Smudger]

My brain hurts... goodnight all... and thank you...

[PappyJ]

Fluid moving via Siphon = gravity. Fluid moving via Vacuum = PRESSURE. Basic physics.