I am also researching John George Mathis and Katherine Hellreigel. I found in the 1880 US Federal Census that John George Mathis was listed as George Mathias. I also found Joh Mathis listed as a passenger on the ship Harmonia from Hamburg, Germany to New York. His birthdate was estimated to be 1845 (26 years old in 1871). He was travelling with another Mathis on this trip, Ph Mathis (29 years old in 1871). Does anyone have information on either of these 2, I am proposing brothers?