Alt-BEAM Archive
Message #01544
To: beam@corp.sgi.com
From: Jean auBois aubois@trail.com
Date: Tue, 16 Mar 1999 10:34:49 -0700
Subject: [alt-beam] Re: `Green Thumb'
I believe that the basic difficulty with this design is being missed here.
Someone mentioned that it is very difficult to obtain very efficient pumps.
Someone else mentioned that the only liquid valves that seem to be
available are these hulking things that take 12 or 24 volts or the like.
It just is hard (energy-wise) to move or regulate the flow of something
like water.
Just to give you an idea of what the difficulty is, put your finger in
front of your most active photopopper or photovore. It is rather easy to
stop it from moving at all, isn't it? The "wheels" spin but it is fairly
trivial to keep it from going anywhere. Now, take a drinking straw and,
say, fill it half full with water and hold it upright with your finger at
the bottom. It takes rather a lot more pressure to keep it from leaking
than it did to keep your photobot from moving, doesn't it?
Given that the typical photobot transforms what available light energy
there is into mechanical energy pretty efficiently I hope that you can see
that it just isn't going to be easy to provide enough "oomph" either to
pump water or to interrupt its flow. Furthermore, if you are using a pump
and there is ANY head of water above it, you also have to keep the pump
from spinning just because of hydrostatic pressure. Indicating to a human
(or a hyperintelligent pet ) is just hugely easier to do than to
solve the mechanical problem involved.
The real challenge would be to invent/design a valve that could operate at
photo-BEAM energy levels. I think that it would be extremely cool if
someone could do that.
It is easier to keep one of those terra-cotta plant waterers filled (and
cheaper as well) than most of the schemes that have been introduced and
they supply water even more slowly than a drip-waterer. They make them
these days where you screw on a 2 liter bottle whose bottom has been cut
off (and which stands upside-down) which can supply water for an orange
tree for half a week or better (personal experience). I'm not trying to
stifle inventiveness here -- in fact, I really hope someone comes up with a
clever way of solving the valve problem.
JaB
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