I started with a home made unit back in about 1959. I've found a slew of coins from the 1800's. I guess the single oldest thing was a Civil War era rifle wrapped in oil cloth that had long since lost its protective ability. That was near Olustee Florida, the site of the only major battle of the war in Florida. The South won that one leaving Tallahassee as the only Southern capital not to fall during the war. I found that in the mid sixties and sold it to a collector. The area is a state park now and treasure hunting of any kind is not allowed. However, there is a pond there that still holds artifacts. People sometimes see a cannon there when water is low.