Thank you for looking, Shane. Other than the marriage record and the baptism records for four of the five children at St. Peter's, all of my information comes from a little history written in 1942 by my GGM, Charlotte Chapman Rowett Tansey. She was the daughter of the youngest Byrne child, Cecilia Charlotte, and was well-acquainted with her uncles, Henry and Charles. But, of course, there could be errors in the history.
According to that history, Henry, Sr. died before his children were grown, not sure of the year, am guessing it was around 1835, possibly earlier? and haven't found a death notice yet. His wife, Mary Shean Byrne, also died, not too many years after her husband, and I don't know if they had to leave their house at that point, but I would assume they did. According to the history, Charles and Henry did attend college, and the girls were sent to boarding school before the family money ran out. After that, they all earned their livings teaching, and the girls were finishing governesses for a period of time.
Henry Lowe Byrne taught mathematics at LSU in New Orleans, among other things, and then went back to Dublin about 1876, his health in decline, and died there about 1881. I might have found his death online, will have to send for it to see if looks correct.
The records at St. Peter's spell the name Byrn and Byrnes, but Charlotte uses the spelling Burns for her mother's maiden name. "My grandfather, Henry Burns was a barrister, an alumnus of what is now larger and is the University of Ireland. Then it was Dublin College. When Mother remembers her father she was a small child, the youngest of five, Mary Anne, Charles, Francis Dorothea (Fanny), Henry Lowe, and herself, Cecilia Charlotte."
I haven't located anything to back up her memories yet, except for the marriage and baptism records, though. I have been trying to organize myself as to which addresses to send away to for what type of record.
Alexander Campbell, Jr. was a first cousin to the Byrnes children, and I found his parents marriage records and his baptism in the St. Peter's records. He was a divinity student and emigrated to Canada, where he became, according to that little history, the ranking Episcopal bishop in Canada by 1882.
The extended family, whoever they were, must have been involved with the younger children after the parents were both gone, because when Cecilia, the youngest, followed her brothers to America, the family made her wait until she was 18, and then she came over under the chaperonage of a much older and reliable woman, a governess, Miss Leigh, and on a sailing ship, because the family had no faith in steam ships.
Mary Anne Byrnes (Burns?) stayed in Ireland and England, and became a bluestocking. She wrote articles for The Freeman's Journal, though I don't know if she used her own name or a pen name.
Well, that is considerably more info than you asked for! Sorry, I'm losing perspective, so deep into the fun of trying to unravel this mystery. Thank you for any direction you can point me in.
