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Posted by Pennies from Hades on November 22, 2007, 10:53 pm, in reply to "Re: Is There No Rest for the Wicked?"
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OK so to continue .. I'm sure to go off topic a bit (it's the first time). Let me talk a little bit about probes. I've had some reasonable success with my home probes (as opposed to alien probes) 
An old discarded printer/typewriter has an admirable probe in the form of the platen bar. Now here I go with the golf balls again .. I drill a hole deep into the golf ball and then glorp it full of hotmelt and ram home the probe end. Flourescent skewered golf balls look neat : ) It's important to drill and glue properly .. the problem arises when going for the deep probis. Extraction can easily come to a sudden halt when the golf ball gets ripped off the end of the probe. Now you are in the trouble. Better to avoid zee troubles and just make sure it doesn't come off. OK enough about those .. how about an instrumented probe? We've all thought about that .. but what kind of instrumentation exactly are you referring to Mister? Well how about an acoustic pickup up around the handle. My thoughts are that given a bit of tip-end material selection one should readily be able to assess are we hitting copper, clad or silver. If we really wanted to get fancy have an IR link to a palm-top that does FFT analysis on the signal and gives a frequency match (to a set of calibration coins). Sources of error include stacked coins. Coins on edge may or may not present a problem.
I mentioned a ferrite-core probe earlier. This would be used for the positive ID on hotrocks and tramp iron in a baked-earth, hard as rock desert dig (ostensibly in search of nougets). yumm.
We get a hit .. we drill down with a battery- powered lineman drill. We insert a ferrite rod that is long enough to extend to the surface. We measure for the presence of magnetic fields as conveyed by the ferrite-rod (to the surface). Variuos ghost-busting EMF meters are up to the task. Gauss Doctor comes to mind. Now we extract the ferrite rod and introduce a high-strength magnet into the hole. This magnet could be encased within some appropriate copper tubing. It is our intention to impart some residual magnetism into the target. We assess how successful we have been by removing the magnet, re-introducing the ferrite rod, and again, measuring for the presence of (conveyed) magnetic fields. No shortage of mag fields present? Hmmm .. prolly not a nouget : ( No new mag fields? Hmmm .. dig on! I really like using the Wild Planet detector in the hole .. no signal? dig on and use the thin typewriter platen probe to get a fix on it. I have an assortement of different platen diameters (and lengths). I've succesfully probed two feet deep .. I like watching the kids faces when they feel the thump thump through the soles of their feet. The local park used to be a brickyard and they layed two feet of dirt on top. I get to sharpen my various large relic hunting skills. I just thunk them .. I don't bother with the dig. I like the kids faces : )
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