On 19 Apr 2004 10:59:08 -0700, (Don)
vaguely proposed a theory
.......and in reply I say!:
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A warning with all water levels. You must not have any air bubbles in
the line. It can stuff everything up. The same goes for any rises and
falls in the line, as these will probably create air bubbles.

Such is my experience. I had wrong readings because of air bubbles.

I _believe that if the air bubble occurs _and the water levels are
already exactly equal, and you don't alter anything_ then you are OK.
Any change with an air bubble and you will get wrong readings.

IME.

As far as the actual levelling goes, depends what you have. I have
done them with shovels and string lines, working in smaller squares to
keep the scale down to size. I also use a scrape stick once I am close
to get larger areas of flat.

But I would use a compactor very thorougly, then re-level, then
recompact, expecially if you are going to cement/brick/pave afterward.
Also remember that string lines stretch and sag. They need to be
_tight_..did I say _tight_? The better the job, the less cement you
need.

My FIL was a commercial grano worker, and used shovels, but had a
dumpy level and used to place a perimeter of oregon planks , with
spikes in the ground every 2 metres' square or so, and work around
those. The spikes were very accurate (woe betide any poor ******* that
kicked one! DAMHIKT) and stuck up the expected depth of the cement,
say 100mm. When they laid the cement, they would simply work to the
top of the grid of spikes.

The box grader is a good idea, but takes some skill to get really
nice. I would still be finishing with a shovel.

And compact compact compact. This will increase your workload, but you
will not regret it.

My dream is to have a layout that allows a really heavy bar or some
such to be dragged across the top of levelled rails either side,
simply levelling, then comnpacting and filling any missed bits, then
again, and again, maybe working in strips. I have about 4 big pads to
do at least, where I am, so it may be worth my while.
************************************************** **
I went on a guided tour not long ago.The guide got
us lost. He was a non-compass mentor.........sorry
.........no I'm not.

"Old Nick" wrote: (clip)I _believe that if the air bubble occurs _and the
water levels are already exactly equal, and you don't alter anything_ then
you are OK. Any change with an air bubble and you will get wrong readings.
^^^^^^^^^^^^^
The water hose is essentially a U-tube, in which the water levels are
PRESUMED to be at the same level in both legs. Obviously, if there is air
on one side, the weight of water required to match the other leg will stand
higher in that leg, introducing an error. The best way to make sure this
doesn't happen is to bring both legs together and see that the levels match.
To be doubly sure, raise the ends of the hose, so any air rises and escapes.
Once this is done, there is no way for air to get in, and the system should
be accurate, no matter how you drag the hose, or whether it goes over bumps
or low spots.

On Tue, 20 Apr 2004 06:35:02 GMT, "Leo Lichtman"
vaguely proposed a theory
.......and in reply I say!:
remove ns from my header address to reply via email

Point taken. I was being cautious. It's hard to get sure that there is
no air in 15 metres of hose, though, by raising the ends up till there
are no folds G

Clear tubing is the safest. I saw a couple of mentions of garden hose.

Once this is done, there is no way for air to get in, and the system should
be accurate, no matter how you drag the hose, or whether it goes over bumps
or low spots.



************************************************** **
I went on a guided tour not long ago.The guide got
us lost. He was a non-compass mentor.........sorry
.........no I'm not.