Treasure Hunter

D is searching for treasure using his new metal detector. His reward for today's effort two old pennies and a bit of a soft drinks can. Ah the joys of the treasure hunter.
He did tell me has has recovered gold coins and jewellery. Or so he says...

Apparently his machine sends signals in a cone shape into the ground which can detect an old penny up to a foot deep and for larger pieces of metal about three feet.