Mary Parsons, Countess of Rosse: Astronomer, Engineer and Photographer (1813–84)

Guest post by Henrietta Heald

Photograph of Mary Parsons, Countess of Rosse. Credit: Birr Trustee Company.

Mary Parsons, Countess of Rosse, deserves a place of honour among pioneering scientists and engineers of the 19th century, but – as is the case with so many other women in the field – her life and work have been under-researched and almost entirely forgotten.

For the preservation of Mary’s memory, we owe a debt to her son Randal, who wrote a brief, unpublished account of Parsons family history.[1] ‘My mother was skilled in modelling in wax and made all the moulds for the ornamental work of the large bronze gates at the entrance of Birr Castle,’ noted Randal, going on to explain that the countess also designed cast-iron and bronze gates for the castle keep, embellishing them with heraldic devices. Familarity with blacksmithing allowed her to cast both sets of gates herself, using a peat-fired forge in the castle grounds.

The forge had been built in the 1840s for casting the speculum, or mirror, of the Leviathan of Parsonstown, the giant telescope erected at Birr, in the centre of Ireland, by Mary’s husband, William Parsons, 3rd Earl of Rosse. The telescope’s 56-foot-long wooden tube and hoist were fixed between two castellated brick walls 50 feet high and 70 feet long, and movement was controlled by chains, pulleys and counterweights. Its 72-inch-diameter speculum made the Leviathan by far the most substantial telescope ever built, and it would remain the largest in the world for three-quarters of a century, until overtaken in 1917 by the 100-inch Hooker telescope on Mount Wilson in California. The Leviathan can still be seen today in the grounds of Birr Castle, Co. Offaly; the speculum, weighing four tons, is on display at the Science Museum in London. 

Lord Rosse used the telescope to make important astronomical discoveries, including the true nature of nebulae – objects resembling luminous clouds of gas among the stars. Visitors flocked to Birr to see and use the wondrous instrument, and worldwide fame descended on its creator; in 1848 he was made president of the Royal Society, Britain’s most august scientific body.

William Rosse’s inventive genius and the significance of his contribution to human knowledge are beyond doubt. However, as described in my book Magnificent Women and Their Revolutionary Machines,[2] it is much less widely recognised that Rosse owed a supreme debt to his wife, Mary (née Field), who provided intellectual, practical and, above all, financial assistance.

Since there was no public money available to pay for the expensive equipment, materials and machinery that the inventor required at Birr, he had to fund his experiments from his own pocket – but he was far short of possessing the huge sums required. In the event, the cost of building the Leviathan, reckoned to be about £12,000 (more than £500,000 in today’s money), was met largely from the income of his wife’s Yorkshire estates.[3] Among the few recent writers to acknowledge Mary’s talents and role in her husband’s success is the curator Rupert Cole, in a 2017 blog for the Science Museum.

The daughter and co-heir of a rich landowner, Mary Field was born at Heaton Hall, the family home in Bradford, West Yorkshire, in 1813. She and her sister, Delia, were educated at home by a governess, Susan Lawson, who encouraged Mary’s creative talents and wide-ranging interests, which included astronomy.[4] By the time the Leviathan came to be built, Mary knew enough about astronomy to help her husband with his calculations. Even more unusually for a woman of her class, she was a skilled blacksmith, and much of the ironwork that the supported the telescope was made by her.

William and Mary were married in Yorkshire in April 1836 in circumstances that seemed less than auspicious. Just a year earlier, in the family’s absence, a disastrous fire had broken out at Birr, started by the flame of a candle left burning in an attic. The central section of the castle had been completely destroyed, so that when the newly married couple came home, they had to live in the wings on either side, which had survived because of the extraordinary thickness of their walls.

In the years that followed, the castle was restored and – under Mary Rosse’s direction – many alterations and additions were made to the demesne, as the estate was known. In the dry moat between the castle and the town, a forge and workshops were constructed, and furnaces for melting brass were installed in a corner tower. A storehouse for peat or turf – used to fuel the forge – was created in another tower, and an engine house with grinding and polishing machinery for making the telescope mirrors was set up in the keep.

When the Irish famine took hold in 1845, Mary Rosse initiated bold schemes at Birr to provide jobs for local people. In collaboration with her uncle Richard Wharton-Myddleton, a former army officer, she redesigned part of the castle grounds, employing more than 500 men in building works that would continue for several years. Later she added a new wing to the castle to accommodate her growing family of children and their tutors. She also built a stable block and a gatehouse, which would be used by her sons as a laboratory.

Photograph of Mary Parsons, Countess of Rosse (seated). Credit: Birr Trustee Company.

Mary not only made detailed architectural models, using visiting cards, of the various new buildings to be created, but also embarked on an experimental venture to record in images the groundbreaking developments that were taking place at Birr – for she was a pioneer in the science and art of photography.

‘At a time when photography was invented, [my mother] had a photographic room fitted up adjoining the workroom and spent much time there,’ wrote Randal Parsons.[5] ‘The process of printing on wax paper was her special delight and many were the beautiful photographs that she took. She joined the London amateur society, and obtained a prize for a photograph of the large telescope.’ The countess also tried stereoscopic photography, which gave the illusion of three-dimensional depth. Her darkroom was closed up after her death, only to be rediscovered intact a hundred years later, with all its original equipment and shelves of bottled chemicals – representing a treasure trove for historians of photography.

Ambitiously, Mary Rosse sought to record the development of the monster telescope, often including human figures in her compositions to emphasise the instrument’s giant proportions. Writing in the 1850s to the inventor and photography expert William Fox Talbot, her husband enclosed a few examples of Mary’s early attempts to capture the Leviathan.[6] Fox Talbot commented that the images were ‘all that [could] be desired’ and recommended them for exhibition at the first show of the Photographic Society in London.

By the end of 1854, the year in which she took up photography, Mary Rosse had given birth to eleven children. Her first child, Alice, was born in 1839 but died of rheumatic fever at the age of thirteen. Other children died in infancy, leaving six brothers, only four of whom – Laurence, Randal, Clere and Charles – survived to adulthood. In spite of her other commitments, Mary found a great deal of time to devote to her children, and they loved her dearly. She was keen to promote their Christian education, going so far as to write her own version of the Bible that would be easy for them to understand. Published in four parts as Granny’s Chapters, the work was designed to be read by her children and grandchildren.

A photograph taken by Mary of her three sons, Clere, Randal, Charles and Jane Knox (sister of Lord Rosse) at the mouth of the Leviathan telescope. Credit: Birr Trustee Company.

Mary also devised plenty of amusements for children and adults alike. With the help of her husband’s cousin Mary Ward, an exceptionally talented biologist and illustrator, the countess put on a spectacular show of homemade fireworks to mark the Great Exhibition of 1851. ‘Fireworks were then the fashion, made on the spot,’ remarked Randal, ‘and a great display was once given in front of the castle to which all the neighbourhood was invited.’[7]

The Parsons boys were tutored at home, and from an early age those who showed an aptitude were encouraged to study science and engineering. One of their teachers, Robert Ball, a future Royal Astronomer of Ireland, was struck by the extraordinary ability of the youngest son, Charles, who even as a young boy seemed always busy making machines. Charles would one day take his place among the first rank of engineers as the inventor of the compound steam turbine. Ball later admitted how honoured he felt to have been responsible for ‘instilling the elements of algebra and Euclid into the famous inventor who has revolutionised the use of steam’.[8]

Three of Mary Rosse’s four surviving sons grew up to become distinguished engineers, while Randal entered the church, becoming rector of Sandhurst military college. The eldest son, Laurence, who succeeded his father to the earldom in 1867, inherited his parents’ love of astronomy and was involved in observations of the Orion nebula made at Birr over a twenty-year period, of which he made drawings. Laurence is best remembered for measuring the heat of the moon with astonishing accuracy – a feat that was recognised only long after his death.[9]

The outstanding legacy of Mary Rosse is plain for all to see – not only in the lives of her children but also in the achievements of later generations. Notable among her grandchildren was Rachel Parsons, whose brilliant brain secured her a place in 1910 at Cambridge University, where she was one of the first three women to read Mechanical Sciences. Rachel was the daughter of Charles and Katharine Parsons, both of whom encouraged her interest in engineering. In 1919, Katharine and Rachel, mother and daughter, founded the Women’s Engineering Society, the first professional organisation in the world dedicated to the campaign for women’s rights.

And just like the beacon of light that Mary Rosse lit for women in the mid-19th century, the pioneering spirit of the Women’s Engineering Society still shines strongly today.

About the author

Henrietta Heald is the author of Magnificent Women and Their Revolutionary Machines (Unbound, 2019), published to mark the centenary of the Women’s Engineering Society. 

[1] Randal Parsons, Reminiscences, privately printed, c.1908. Birr Castle Archives, Birr, Ireland.

[2] Henrietta Heald, Magnificent Women and Their Revolutionary Machines, Unbound, London, 2019.

[3] David H. Davison, Impressions of an Irish Countess, The Photography of Mary, Countess of Rosse, Birr Scientific Heritage Foundation, Birr, Ireland, 1989.

[4] Susan McKenna-Lawlor, Whatever Shines Should be Observed, Samton, Dublin, 1998.

[5] Randal Parsons, Reminiscences.

[6] W. Garrett Scaife, From Galaxies to Turbines: Science, Technology and the Parsons Family, Institute of Physics Publishing, Bristol, 2000.

[7] Randal Parsons, Reminiscences.

[8] Obituary of Sir Charles Parsons, Proceedings of the Royal Society, vol. CXXXI, June 1931.

[9] Patrick Moore, The Astronomy of Birr Castle, Tribune Publishing, Birr, Ireland, 1971.