Mason, Thomas Holmes (1877–1958), photographer, naturalist, meteorologist, and businessman, was born 9 September 1877, eldest among three children of Thomas Mason, optical manufacturer, and Sarah Mason (née Barry) of Dublin. Having worked in the family business in Parliament St., Dublin, since the 1890s, Mason succeeded his father on his death (3 July 1913) becoming the fifth generation of the family to lead the business. Expanding both the premises and scope of the business, Mason established a photographic materials department alongside the developing and printing works started by his father. He expanded these complementary areas, taking advantage of the growing contemporary interest in photography. He enlarged (1914) the premises at 5 & 6 Dame St., to which the firm had moved in 1894, as well as converting the business from a sole trader into a limited liability company. On 23 May 1923 (Ir. Times, 24 May 1923) he was appointed a peace commissioner by the Free State government.
Mason was a keen cyclist; his tours through the Irish countryside as a youth, as well as his interest in photography from the age of twelve (he would take over 20,000 pictures by his death), led him to the study of the natural world and Irish archaeology. This culminated in his publication of The islands of Ireland: their scenery, people, life and antiquities (1936), visually recording the minutiae of Irish folk life and the natural beauty of the island landscapes.
Mason did not restrict his interests to any one discipline and was involved in a multifarious range of organisations: member of the Dublin Field Club, one-time president of the Irish Society for the Protection of Birds, member of the Dublin Zoological Council (serving as honorary vice-president from 1952), member and president (1926) of the Photography Society of Ireland, member of the Geographical Society of Ireland, and member of the National Monuments Council as well as president (1951) of An Taisce. He was also president of the Dublin Mercantile Association (1923) and the Dublin Rotary Club and a fellow of the RSAI.
He was elected MRIA (1931) and contributed numerous articles to the Academy's Transactions and Proceedings on subjects ranging from the history of the optical profession in Dublin to Celtic archaeology. Mason provided meteorological information to Irish newspapers from his home observatory at 39 Kenilworth Square before the establishment of the Irish meteorological service (1936). His other interests included Irish moths as well as Irish lantern slides, on which he published Catalogue of photographic lantern slides of Irish scenery and antiquities [n.d.] and Catalogue of lantern slides of Irish antiquities (1928).
Mason was the seventh member of his family to be made an honorary freeman of the city of Dublin (29 April 1903), one of the last such hereditary appointments. His wife Margaret Evelyn, whom he married c.1909, was a fellow presbyterian. Three of his four sons succeeded him in the family business, which celebrated its bicentenary in 1980 and traded into the third millennium. He died on 12 February 1958, leaving his library to the Old Dublin Society and TCD.