A Day When History Was Made

Andrew Kenneth Fletcher gravitystudy at hotmail.com
Sat Mar 4 08:53:46 EST 2000

Bob Vickery <vickery at mpx.com.au> wrote in message
news:B4E6F4849668B637B2 at slsdn55p48.ozemail.com.au...
> In article <89f3bb$s0a$3 at newsg1.svr.pol.co.uk>,
> "Andrew Kenneth Fletcher" <gravitystudy at hotmail.com> wrote:
> >Hi everyone
> >
> >Could we re-open this topic for discussion? I feel I have something new
> >add to this field and wander if others find the accepted explanations for
> >fluid transport somewhat confusing.
> >
> >Has anyone developed a working model which demonstrates a lift of water
> >higher that the 10 metre limit set down in the physics literature some
> >hundred years ago.
> >
> Not as such.  You would have to take a capillary tube full of water and
> draw it out to a vertical height greater than 10 m.  The capillary would
> have to be strong enough not to collapse inward under the tension
> by the column of water.  It would also have to  be permeable to water to
> allow evaporation at the top and entry of water at the bottom.  This can't
> be done with synthetic materials.
> What can be done is to measure the strength of water.  Plant physiology
> texts describe experiments to do this.  It turns out that columns of water
> in capillary tubes are strong enough to be pulled up tall trees.
> Calculations based on surface tension also show that water columns should
> be very strong.
> >I have read about osmosis, capillary action and root pressure, but find
> >lacking in scientific validity.
> >
> These phenomena are not enough to explain the ascent of sap.  The theories
> behind them are valid enough, it is just that they are not relevant to
> explaining how sap gets up tall trees.  Some text books are pretty
> misleading on these topics.  The one you quote ( GCSE BIOLOGY, D.G.
> Mackean. ISBN 0-7195-4281-2 first published in 1986.)  seems pretty
> accurate.
> >Has anyone heard of alternative theories and if so could you provide us
> >the location to start this thread.
> No.
> Cheers

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