Historian Bill Watson in his office at Immaculata College in Malvern, Pennsylvania on March 8, 2014. Exposed roots found under a stump near railroad tracks in a place now known as Duffy's Cut, once ... more 
Historian Bill Watson in his office at Immaculata College in Malvern, Pennsylvania on March 8, 2014. Exposed roots found under a stump near railroad tracks in a place now known as Duffy's Cut, once held in their grip buttons, human bones and old coffin nails - vital clues in a centuries-old unsolved mystery. The stump, pulled up several years ago, stood over the final resting place of seven of 57 Irish laborers who perished at the railroad construction site in 1832, during an outbreak of cholera. REUTERS/Mark Makela (UNITED STATES - Tags: SOCIETY) less 
1 / 7
Reuters | Photo By MARK MAKELA / REUTERS
Sun, Mar 9, 2014 11:56 AM EDT