The Rt Hon. Mary Parsons, Countess of Rosse (née Mary Field; 1813–1885), was a British amateur astronomer and pioneering photographer. Often known simply as Mary Rosse, she was one of the early practitioners of making photographs from waxed-paper negatives.
Mary Field was born in 1813, in Yorkshire, the daughter of John Wilmer Field, a wealthy estate owner.
Through her family she met the then Lord Oxmantown (1800–1867), an Anglo-Irish nobleman, and they were married on 14 April 1836. In February 1841, Lord Oxmantown succeeded his father in the family peerage to become The 3rd Earl of Rosse. Mary, Baroness Oxmantown, thus now became The Countess of Rosse.
In the early 1840s the couple became interested in astronomy, and Mary helped her husband, Lord Rosse, build a giant telescope, that was considered a technical marvel in its time. She was an accomplished blacksmith – which was very unusual for higher class women of this time – and much of the iron work that supported the telescope was constructed by her.
The Countess of Rosse gave birth to eleven children, but only four survived until adulthood:
- Lawrence Parsons, 4th Earl of Rosse (17 November 1840 – 30 August 1908)
- Reverend Randal Parsons (26 April 1848 – 15 November 1936)
- Hon. Richard Clere Parsons (21 February 1851 – 26 January 1923), apparently made a name for himself building railways in South America.
- Sir Charles Algernon Parsons (13 June 1854 – 11 February 1931), known for his commercial development of the steam turbine. His wife, Lady Katherine Parsons and their daughter Rachel Parsons were founders of the Women's Engineering Society and its first and second presidents.
Mary, Dowager Countess of Rosse, died in 1885.
In 1842, Lord Rosse began experimenting in daguerreotype photography, possibly learning some of the art from his acquaintance William Henry Fox Talbot. In 1854, Lord Rosse wrote to Fox Talbot saying that Lady Rosse too had just commenced photography, and sent some examples of her work. Fox Talbot replied that some of her photographs of the telescope "are all that can be desired". Lady Rosse became a member of the Dublin Photographic Society, and in 1859 she received a silver medal for "best paper negative" from the Photographic Society of Ireland. Many examples of her photography are in the Birr Castle Archives. Much of the topography of Birr Castle that she portrayed has changed very little, and it is possible to compare many of her photographs with the actual places.
- For more on waxed-paper negatives, see John Towler, "Negatives on Paper", chap. 29 of The Silver Sunbeam (New York: Joseph H. Ladd, 1864).
- "Birr Castle Desme – History of the Telescopes". Archived from the original on 24 December 2008. Retrieved 5 January 2009.
- "Obituary The Hon. Lady Parsons | Women's Engineering Society". www.wes.org.uk. Retrieved 4 July 2019.
- "Presidents Past & Present | Women's Engineering Society". www.wes.org.uk. Retrieved 4 July 2019.
- "Birr Castle Desme – Mary Rosse and Photography". Archived from the original on 26 December 2008. Retrieved 5 January 2009.