EddieR said:
As far as the rods not getting water, I don't know for certain that there is water there. There are no visual indicators to show it (creeks, springs, etc.).
Now the copper wire part is easy (as is the silverware). This is East Tennessee. We are not boxed in by houses 3 feet away on either side of us. My grandparents have well water, city water doesn't run out that far in the country. The property they bought is just fields and woods, there are no houses around, and power lines do not cross the property (at this time, anyway).
I'm not sure about the moss thing either....
Well, even in East TN, there must be some other folks that may have silverware (or stashed gold), other sources of water and certainly there would be other copper products somewhere outside the confines of your grandparents' land borders.
For one thing, the house they live in no doubt has copper wiring in it. Also, the vehicles on the property all contain a certain amount of copper wiring. How many vehicles were on the property at the time?
So, you see, now we have a separate issue; that being one of "distance" (proximity) as well as "element discrimination".
How do you suppose it was that your grandmother (armed only with a pair of brass rods) only allowed the rods to react to the copper on her land that was a part of the sought after still? And I would still like to know how she "tuned" the rods to only react to the buried copper?