I have information relating to my line in America. So far, I have been unable to trace before 1890. I haven't heard of Blackwood in Ireland, however. All I have known re: the name was from England and Scotland. Interestingly enough, I found out that the Hon. Henry Blackwood was captain of the Euralyus, a British Frigate, and was in command of the in shore squadron for Nelson during Trafalgar. He was witness to Nelson's will on the Victory.