William Archer FRS, Irish naturalist, librarian and microscopist especially interested in Protozoa and Desmids, is born on May 6, 1827 (some sources say 1830), in Maghera, County Down.

Archer is the eldest son of Rev. Richard Archer (1796? – 1849), perpetual curate of Maghera hamlet, County Down, and his wife, Jane Matilda (née Campbell). Nothing is known of his education, though his two younger brothers attend Trinity College Dublin (TCD). At some point, he apparently appears to become estranged from his family.

Archer moves to Dublin around 1846, where for many years he pursues a business career. He achieves fame as a naturalist, and in 1849, is one of the twelve founder members of the Dublin Microscopical Club, of which he is the secretary and moving spirit for many years. Between 1858 and 1885 he writes over 230 scientific papers on Irish fauna and flora in the Quarterly Journal of Microscopical Science, the vast majority of which are short notes on desmids collected in Ireland. Sometimes the same article is published in two or more journals.

Archer is a member of the Dublin University Zoological Association and is elected a member of the Royal Irish Academy (MRIA) on January 10, 1870, and Fellow of the Royal Society (FRS) in 1875, on which occasion it is stated that he has “a knowledge of the minute freshwater organisms unparalleled among British naturalists and perhaps not surpassed for any other country.”

Archer begins a new career when he becomes librarian of the Royal Dublin Society (RDS) in January 1877. The bulk of the society’s library is being taken over by the state to form the National Library of Ireland. He becomes the chief librarian of the new institution and has the task of overseeing the changes. Most of the ideas put forward in his pamphlet, Suggestions as to public library buildings . . . with especial reference to the National Library of Ireland (Dublin, 1881), are used by Sir Thomas Newenham Deane in his design for its new building, which opens in August 1890. His adoption of the Dewey Decimal Classification system and the inception of a dictionary catalogue, both novel in the day, are to prove of lasting value to users of the library.

In poor health, Archer retires in 1895. He dies, unmarried, at his home, 52 Mount Street Lower, Dublin, on August 14, 1897. He is a shy, modest man, who declines professorships at the Royal College of Science for Ireland and at Trinity College Dublin (TCD), and who is nominated for membership of the Royal Irish Academy (RIA) and the Royal Society without his knowledge.