I'm actually using this post to word-process an abstract for an article due at 5PM today. (The massive humidity in my area is wrecking its usual havoc upon my computer.)
I've previously posted an article by means of which I've (hopefully) corrected the Australian physicist Dr. Stephen Hughes, who says that the principal motive force acting upon a siphon system is gravitation, rather than pressure differential (i.e., suction).
Here's a precis of Dr. Hughes' article:
http//www.google.com/hostednews/afp/article/ALeqM5juBAXGcLlUjTCgERQXnBuP1COv5g
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And here's proof positive that pressure differential, and not gravitation, supplies the chief motive power acting upon a siphon system, delivered by a little glass bird who flew into my life back in the late 1960's:
http://www.youtube.com/watch?v=r31C678V66o&feature=related***
Obviously, gravitation supplies the regulating pendular motion to the bird, but it's the pressure differential between the humid atmosphere of earth in the face of the highly volatile compound methylene chloride = dichloralmethane = CH2Cl2 that causes the displacement of the center of gravity within the machine which causes the bobbing motion. In other words, pressure differential is more powerful than gravity within this system, as it causes the liquid CH2Cl2 to be sucked into the siphon tube (i.e., the bird's neck) against the force of gravity. (I've already conceded that gravity, facilitated by the extra length of the tube in the downward as opposed to the upward section of a classic siphon tube, prevents backpressure from the atmosphere from blocking the flow of fluid initiated by the flow-initiating pressure differential supplied by sucking on the tube at the start of the siphoning process.)
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Suggestion for an experiment:
Attempt operating the little glass bird in a 100% relative humidity environment (which would prevent the evaporation of water which cools the bird's head, thus preventing the expansion and condensation of the gaseous methylene chloride, the displacement of whose center of gravity causes the bobbing motion).