However http://eprints.qut.edu.au/31098/ which was written by the physicist that submitted the correction to the OED claims, contrary to wikipedia, that the tensile strength of water is relevant.
Anyone have the ability to run a siphon and pull the middle up about 50 feet in the air? If atmospheric pressure is key, it should stop working at something like 30 feet high. If tensile strength is key, it should go several times that height.
Edit: I accidentally said that the tensile strength of water was said to be irrelevant, not relevant.
I was a little surprised that "a siphon with a large leg" works (even tested it out to double check [1]). Could someone explain this to me - surely the weight of the water inside the "large leg" exceeds the weight in the little leg. Why doesn't that make the water move the other way [2]?
2. I realize is impossible because it would end up moving water from a lower reservoir to a higher one, but proof by contradiction doesn't count - I'm trying to understand what's happening at the point of the cap (in [1]).
You have an entire ocean of water - miles across, yet with your hand you can make a dam that keeps out the weight of the entire ocean.
The reason is that it's only height that matters - not width. The weight of that very wide ocean is supported by all the water under it.
It's the same in a siphon. All the water in that wide leg is supported by the water in the bottle.
The difference in height however is not. Maybe think in terms of pressure. The bottom of a tall column of water is under higher pressure than the bottom of a short one. The width of the water however doesn't matter. Pressure is pounds per area, so while there are more pounds at the bottom, there is also more area, so area cancels out.
Exactly the explanation I was looking for, thank you! Another helpful thought spawned from it is that most of weight of the water in the bottle is being supported by the bottle's structure itself (I think you actually meant to say that but mis-typed).
Nice catch.