I've always thought optical might be the best way to go
but everyone seems to resist that idea for one reason
or another.

A mirror at the pivot point with a small radius
not sure, but mechanical amplification
looks possible with a laser.

I'm just not smart enough to figure it all out.

Need a committee of scientists and engineers.

Will anyone send a seismometer to
Mars/Venus or ????

Id like to see what they send if they do.

I think the ladder should be 316 stainless steel.

Regards,
geoff


-----Original Message----- 
From: Andrew Little
Sent: Sunday, November 07, 2010 10:50 PM
To: psnlist@..............
Subject: Re: sensor in a well

Thanks Geoff,
There is an iron ladder down to the water's surface 10m. The house was built in 1923 and we are not keen climb down. I suppose I 
need to monitor the typical fluctuation in water level. Perhaps one of these laser measures as used for room dimensions would work, 
aimed at a suitable float. Once the seasonal variation is determined then a suitable sensor would have to operate over that range. 
If the movement is slight then a coil/magnet float might do the trick. If we are talking 50cm I think I need another solution. 
Perhaps optical?
Andy



On 7 November 2010 22:59, Geoffrey  wrote:
Possibly float a magnet on the surface
held in place by whatever and then
have a coil on the wall of the well ?

or, vice versa.

getting the stuff into place is a big wonder.

I often thought a big water tower might make a good
vertical sensor if you hydraulically amplify
the pressure changes related to ground motion.
The water is a fluid and non-compressible
with lots of mass and momentum, every tiny undulation should
cause considerable pressure change.

Sort of like a little pressure on the break pedal causes
big pressure in the hydraulic cylinders.

When I look at the water tower at Falcon Field
at Mesa AZ, I often think of it as a potential seismometer.

But such a thing must be dedicated only to sensing.

Maybe a denser fluid like mercury ?

A barometer like device that reacts to motion
instead of air pressure.

geoff


-----Original Message----- From: Ted Channel
Sent: Friday, November 05, 2010 6:02 PM
To: psnlist@..............
Subject: Re: sensor in a well




Hi Andy,  Is it possible to email me a pdf or copy of the article....or a .jpg......very interesting.
Ted

----- Original Message ----- From: Andrew Little
To: psnlist@..............
Sent: Friday, November 05, 2010 11:28 AM
Subject: sensor in a well

Hi PSN list,
I have a copy of The Amateur Scientist by C.L. Strong 1960. It is a collection of projects and articles from The Scientific 
American. In the Earth Science section are several articles on seismology. It was this book that first got me interested in the 
subject. One article by Elmer Rexin describes using a float in a well to detect seismic events.
I happen to have a well under my house, it is cut into the limestone, the water surface is 10 Metres below the floor of the cellar. 
I know of one sink-hole on the plateau above the village so It is possible that the well could be connected to an aquifer in the 
limestone hillside. The well in the article did have a connection to lake Michigan and so acted as part of a giant "U-tube".
Anyway, the point of all this is to ask if anyone thinks there could be an advantage in setting up some form of sensor in the well, 
and if so, have you any ideas?
Regards,
Andy




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