Written by the TreasureGuide for the exclusive use of treasurbeachesreport.blogspot.com.
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| Grant Surfacing to The Bottomline With Silver Picture Frame. Photo submitted by Captain Jonah Martinez |
I posted a couple pictures of the frame yesterday, but here is one more. Really great find!
If you didn't see the larger picture I posted yesterday, you should go back and take a look.
If you didn't see the larger picture I posted yesterday, you should go back and take a look.
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Coins have been around hundreds and hundreds of years And they really haven't changed much. The are usually round and flat with a design on two sides. That is a basic design that has worked well and has remained little changed for centuries.
One thing that detectorists probably do not appreciate enough is the effect of the position of coins and other objects in the ground on the signal produced by a metal detector. They usually assume that coins are lying with one face parallel to the coil. That is how air tests are conducted and that is how depth measurements are usually taken. But sometimes a coin can be on edge or at an angle, and that definitely affects the detector reading.
The amount of surface area presented to the coil is an important factor. Tilting the coin (or the coil) affects that.
I gave some tips on cache hunting a couple days ago, and mentioned how you never know what metals or items might be in a cache. The container itself might be what you detect, and the container will seldom be made of a precious metal.
Like I mentioned, canning jars or cans are sometimes used. Not too long ago 23 Peace and Morgan silver dollars were found in a canning jar. There are a lot of variables involved in how a metal detector might respond to that. There were the coins and how they were positioned, but there was also a metal screw cap on the canning jar. The position of the lid is another important factor.
I showed how the Ace 250 responded to a silver dollar not too long ago. You'd think the signal would be much louder for twenty-three coins compared to a single silver dollar. In this case, the silver dollars were stacked but not standing up. They were wrapped in a rag and lying like a wrapped roll in the jar. They were wrapped with a rag, but not as tight as they would be in a regular con wrapper.
The sound was louder than a single coin laying flat, but not as much as I expected. They were standing on end next to each other, so the surface presented to the detector coil was nothing like it would have been if they were scattered out over the ground.
People often talk about the halo affect when talking about coins in the ground, but in this case, the coins were inside a glass jar, so there was no halo affect from the coins. However there was a metal screw lid that was badly rusted.
Detecting the silver dollars lying in a row stacked on the ground without the jar, resulted in a signal that was somewhat louder than a single coin lying flat, but not by a huge amount. They were detected at about a foot. That wasn't very much considering the amount of silver. The surface area presented directly to the coil is very important. I should do a good demonstration and take some good measurements.
Another factor, as they were found, was the canning jar lid. The jar could be buried standing up or lying down. The lid could be facing the coil or on its side. In this case the jar was lying, and the coins were in the position that I just described.
Here is a video showing how the jar full of silver dollars would sound if you sweep in one direction.
That was sweeping in one direction.
I advise sweeping at a 90 degree angle and observing the difference in sound when you are trying to figure out what the item might be.
Below is another short video. This time the coil is moved 90 at a different angle.
I'm sure you noticed how different the signal was.
If an object is round and the item is not made of different parts and the object is lying flat, you'll get the same signal no matter which direction you sweep your coil relative to the object. That would have been the case if the jar was standing up and you swept over the lid of the jar. In that case, you would be hearing the lid more than the coins inside the jar.
My point is that you can tell a lot about a buried object from the signal you get, especially when you sweep from more than one angle. Mixed items or items lying at different angles can be more difficult to identify from the signal alone. That can make cache hunting a tricky. You are not looking individual coins or rings but mixed items that can be buried in a variety of ways.
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There are no significant storms in the Atlantic and not much change in beach conditions.
Happy hunting,
TreasureGuide@comcast.net
