There is a Henry R WATSON, blacksmith, born in Pennsylvania in May 1830 per the 1900 census and living in Mt Pleasant Twp, Delaware County, Indiana as a boarder.There is a notation that he belongs to a different family number than where enumerated on the page. Perhaps you'd want to check that out.IF it's your Henry R, this entry gives his father's birthplace as Virginia and his mother's as Maryland.
Also in that county in 1900 is Sandy B WATSON, age 28, born in Pennsylvania, and likely your Henry R WATSON's son.
Of note, is that there is no Henry R WATSON listed in the online Pennsylvania death index for the year 1912. This is a complete index of reported deaths in the state. So either Henry R did not die in Pennsylvania in 1912 or it wasn't reported.There is a Henry E who died in Berks County and a Harry who died in Philadelphia in 1912.Neither seem likely to be your Henry R.
Familysearch.org has an Indiana death database.I don't know if that is a complete index or not.In a brief check for 1912, I didn't find anything but perhaps you'd want to look more thoroughly.