Day was an important and well-travelled antiquarian collector. He was involved in his family"s extensive saddlery business together with a sports shop well known to Cork anglers. They lived at Myrtle Hill outside Cork until 1906 and after at Patrick"s Hill.
He was president of the Cork Cuverian Society and its successor the Cork Historical and Archaeological Society from 1894 to 1914.
There, he gathered an enormous collection of Irish archaeological artefacts which were auctioned in 1915 and turned up in the collections of John Hunt in Limerick and Walter J. Verschoyle-Campbell, as well as the Birmingham Archaeological Society, the Louth Archaeological Society, the Ulster Museum and the National Museum of Ireland. An ongoing project at the Archaeology Department University College Cork is seeking to trace items from this auction.
His early photographs date from the 1860s and continue until his death. They are atmospheric and depict a Cork which in many ways has disappeared.
Another grandson was the noted writer and wood engraver Robert Gibbings.