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Posted by Pennies from Hades on November 21, 2007, 10:54 pm, in reply to "Is There No Rest for the Wicked?"
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OK as previously indicated, here are some outside-the-coil thoughts on modern penny elimination. First let's size up a few things... all clad coins are magnetic; meaning, they will be not only be attracted to a magnet but also 'absorb' some 'parasitic' magnetism from having come into contact with a magnet. Perhaps 10% of modern pennies are similarly magnetic. These definitely will be within a few centimeters of the surface. Silver of course is entirely non-magnetic. Let's suggest we're coin-shooting a finely-manicured lawn that has targets of all types and description. The owner is intrigued and has given you permission to snipe but 'try and keep the damage to a minimum' are his parting words. So aside from good digging protocol let's suggest we really truly only want to dig clad and silver and watches not to forget rings. No pennies and no deep, troublesome debris. This is a tall order so we better get started. Let's conduct what I call a 'geometry survey'. Look/listen for obvious irrigation pipes and cabling. Establish the utilities. A moderate 7 inch coil should do the job. Let's suggest there really isn't much in the way of utility runs but that there still exists the potential for deep construction fill which we are not really interested in - at this juncture. We're interested in making sure we don't dig it. Deep, corroded wrought iron or alternatively; shiny, olive oil can hits can sound deceptively coin-like. I'm sure we've all experienced the silver platter turning into a rusty old horse shoe or pot-bellied stove lid. My suggestion is to conduct an initial survey with a twin-box machine. This unit is sensitive only toward large objects. We quickly plot out the trouble spots. Ahah! We can no investigate with a standard coil machine KNOWING that hey! it's large and it's probably deep. We can infact snipe around these targets by switching to a smaller coil. A magnetometer would serve to complete the 'roughing survey' by locating any upright iron stakes .. any large iron object will be nicely located. Occassionaly duplex's and singulars (twoonies and loonies) that have come into contact with a magnet - will exhibit a strong 'mag' response. That's fine. But it's not the primary objective of the mag survey. Troublesome mag targets include floppy fridge magnets btw. I'm digressing. Let's assume we have a helper along .. that's a not a big stretch. Helper is carrying a small Wild Planet toy detector and a collection of different colored golf balls. Red for dig, white for modern penny, green for clad and orange for silver - we'll suggest. The Wild Planet will detect to a depth of no more than two inches. It does this with a very sharp and nicely reproducible 'threshold response'. If it's not responding - then the coinlike target is deeper than two inches ... definitely a dig. Let's assume there are a large number of coin-like targets. We can employ numbered golf balls and have a clipboard and take some notes. Eventually a system will evolve hopefully demonstrating positive identification of near-surface modern pennies AND clad (at any depth) AND silver (again at any depth) without having put a shovel into the soil. I think only two types of golf balls need be carried .. one a numbered white one - this gets assigned to each and every potential coin target. The helper records the number and the operator gives some quick comments on how the target is behaving. Videotaping (for later analysis) is not out of the question. Might I suggest mixing the audio in directly thereby eliminating wind-in-the-microphone distortion.
Now for the next phase of our layered approach. We have all the coin-like targets flagged with numbered golfballs - located pretty darn precisely over the target. We can now probe. This probing can be very revealing. Well there are a number of refinements on your standard probe including a magnetic tip probe and a ferrite-core probe. In addition a probe with an acoustic microphone attached to it .. giving a nice ear-to-the-ground approach. Again this signal can be mixed directly onto the video tape.
It's all about documentation and getting a second-opinion. Enuf for now. Thank you for your patience.
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