OK, I found two articles in the Irish newspapers for Alexander Blythe.
The first is a death notice that appeared in the Belfast paper, the Belfast News-Letter on the 4th March, 1890 on page 1 of 8. It is a death notice that reads:
"BLYTHE - February 28, Alexander Harkness Blythe, Board of Works, Four Courts, Dublin aged 56 years."
and the second is in the Freemans Journal of 27th January 1888 and is a long article about the Inquest into the explosion at Four Courts. AHB is mentioned as a carpenter in the employ of the Board of Works and the article includes his testimony.
I can give you both these articles if you do not have access to the Irish newspapers. I would upload them here but I do not know how. Lol.
Lastly, I note that Alexander Blythe is noted in Thom's Irish Almanac and Official Directory of Ireland from about 1866 through to his death in 1890. He is also mentioned in Slater's Royal National Commercial Directory of Ireland. His son also appears later.
I hope that this is all helpful.