Re: Measuring The Geomagnetic field

[brian whatcott <inet@intellisys.net>]

At 21:26 10/7/97 -0700, Bill Beaty wrote:
> On Tue, 7 Oct 1997, brian whatcott wrote:
>
> > The bottle is arranged east-west.
> > The water is 'polarized' with a DC current through the coil for a few
> > seconds, then the coil is disconnected from the current source, and
> > connected to the high-gain audio input.
>
> The SciAm "Amateur Scientist" index site at www.thesphere.com/SAS will
> tell you which issue this one was in.

Actually Bill, people have difficulty in locating this piece in SciAm's
Amateur Scientist index. But if folks want to build a version of this
delightfully complex-sounding instrument, they could email me off line 
for details.

  It has a splendid "fool-proofing" quality.
 If an innocent tries to measure the field strength in disturbed 
conditions, it will not cooperate. This means
NOT
 inside a room
 near buildings
 near many roads.

The biggest single cost is the lantern cell to drive the coil.

> I once saw a project article which mentioned that distilled water works
> poorly because of the presence of dissolved oxygen, and is much improved
> by boiling it in order to degas.
>
> William Beaty

I found it worked well with distilled water, but tap-water works just 
fine.
  These days it might cost as much as $15 to build - but make sure 
you have a physics person to refer to  rather than a moral expert 
( sorry, couldn't resist!)  :-)



brian whatcott <inet@intellisys.net>
Altus OK