A park visitor recently turned in a cannonball found near Indiana
     Dunes National Lakeshore (at the southern end of Lake Michigan).  The
     staff there would like to know if it is datable on the basis of size
     and weight (I've only had it described to me over the phone).
 
     The ball is precisely 15 pounds in weight with a circumference of
     about 15 1/2 or 15 5/8 inches (approx. 5 inches in diameter).  Anyone
     know if this can be dated and, if so, when would it have likely seen
     use?.  Please feel free to provide either a recollection or citation.
 
     Thanks...
 
     Vergil Noble
     NPS Midwest Arch Ctr
     Lincoln, NE