The Science of Metal Detection

A Brief History

Metal detection systems and equipment have been around since the late 19th century. Inventors and scientists figured anyone with such a device that could pinpoint metal would have a distinct advantage while mining or prospecting.  The first recorded use of metal detection was by Alexander Graham Bell during surgery on a shot President Garfield in 1881.

Gerhard Fisher discovered, during testing of his radio direction finder, that his device's signals were distorted in the presence of iron.  Further experimentation led him to acquire the first patent for a metal detector in 1925. A similar invention, patented by Shirl Herr in 1928, was used by Benito Mussolini to recover artifacts from Italian Emperor Caligula's treasure galleons and by Admiral Byrd's second Antarctic exploration. During WWII, Polish Lt. Jozef Stanislaw Kosacki refined the technology for use as a mine detector.  Finally, modern development was perfected by Charles Garrett of Garland, Texas in the 1950s.

Technology

There are 3 primary detection technologies used in metal detection: Very Low Frequency, Pulse Induction, and Beat-Frequency Oscillation.  Digging History members use the Garrett AT Pro, a VLF detector.

The popular website HowStuffWorks.com has a remarkably simple guide that explains metal detection technology in all three of its forms, complete with animated imagery. You can view the guides here: VLF, PI, BFO.


The Digging History Process

Digging History is an autonomous research & recovery team. While we are history enthusiasts we are also hobbyists and collectors; often, during the course of our regular activity we procure artifacts that should be available for public display and education due to their significance. Please refer to our Projects page for items and collections donated by Digging History to such organizations.

Please remember that we are NOT professional archaeologists!  While our methods are not considered to be up to their standards, we do have a system for recovery and collection that suffices to maintain some degree of archaeological context.  However, unlike archaeologists, we do not assert that every item recovered at a site has historical significance.

Artifacts found on sites explored or surveyed by Digging History with the express purpose of historic research will be photographed, gridded, and documented for future research.

We have an open door policy for historical societies and organizations, although we generally interact more with the groups in our immediate area(s). If an artifact is found in Township A, every effort will be made to donate the artifact to the A Historical Society / Museum. If Township A does not have a society, then the artifact will be donated to another nearby organization that claims historic jurisdiction.

All artifacts dug or procured by Digging History with the intent to donate will be cleaned and preserved prior to donation; there is a possibility that we may mount the artifact as well, if such display would assist historical context or the recipient's ability to display it.

NOTE: Due to the nature of our artifact recovery methods, the following suggestions are recommended:

  • Wait until after a rainstorm before mowing your grass! An alternative is to hose down the area. Small animals and lawnmowers are known to re-unearth "plugs" despite our best efforts to fill and tamp the holes we dig.
  • The grass will grow back! We make every effort to maintain the grass root system so that unearthed grass will continue to grow after the hole is filled.  Sometimes it takes some water (rain or from a hose) to encourage the grass to recuperate.  If the grass at a dig site does not recover after a reasonable period, Digging History will re-seed the area at no cost to the property owner.
  • Walk with care in surveyed areas! It is Digging History policy to not re-inter dug items, but also to remove all scrap and garbage from surveyed sites. Due to this, some re-filled holes may leave a depression if a larger object was removed.