Mary Somerville

Mary Somerville
Nationality	Scottish
Known for	Translating and popularizing Laplace; inspiring women's science education
Fields	Mathematics; Astronomy
Occupation	Mathematician and science writer
Notable works	Mechanism of the Heavens; On the Connexion of the Physical Sciences; Physical Geography
Era	19th century
Affiliations	Honorary member, Royal Astronomical Society
Wikidata	Q268702

Mary Somerville (1780–1872) was a Scottish scientist celebrated for her clear, wide-ranging writings on mathematics and astronomy. Largely self-educated in an era when women had little formal schooling, she later translated and summarized advanced scientific works (notably Laplace’s Mécanique céleste) into English. Somerville’s books – including Mechanism of the Heavens (1831) and On the Connexion of the Physical Sciences (1834) – made complex ideas about planetary motion, physics, and natural phenomena accessible to educated readers. Her work helped inspire major discoveries (for example, it hinted at the existence of the planet Neptune) and earned her rare honors for a woman of her time. She became a symbol of women’s intellectual ability and was a strong advocate for women’s education, eventually lending her name to Somerville College at Oxford. Contemporaries dubbed her “the Queen of Science” for her broad knowledge and skillful exposition.

Early Life and Education

Mary Fairfax was born in 1780 in Jedburgh, Scotland, into a well-off family that generally encouraged the education of sons but not daughters. Her father, Sir William George Fairfax, was often at sea and, like many men of the era, believed that rigorous study of mathematics would “injure the tender female frame.” Her mother taught her to read, but Mary received virtually no formal schooling in writing or arithmetic. At age 10 she attended a girls’ boarding school for a year but disliked it intensely, later saying she felt “like a wild animal escaped out of a cage” when freed. After this brief schooling her family expected her to learn domestic skills like needlework and music.

Undeterred, Mary Somerville began to educate herself by voracious reading whenever possible. Encouraged privately by family members—especially her uncle, Thomas Somerville, who helped her learn Latin—she studied geometry and astronomy on her own. As a teenager in Edinburgh, she famously overheard a painter, Alexander Nasmyth, remark that Euclid’s Elements (the classic geometry text) was essential for understanding perspective in art and even astronomy. Intrigued, Mary borrowed a copy of Elements and taught herself geometry with the help of her older brother and family friends. She also cultivated a love of natural science as a child by collecting shells, observing marine life on the Fife coast, and learning the names of plants and animals around her home. Much of her study was done independently at night by lamp or by studying library books, since her relatives often scorned her “unladylike” habit of reading scientific works.

Saint Andrews University professor John Playfair, a family friend, encouraged Somerville’s studies. By 1811 she had begun solving mathematical problems from journals. A solution of an algebraic (Diophantine) problem won her a prize from a scientific society in 1811 – the first public recognition of her mathematical skill. That same year Thomas Somerville introduced her to Isaac Newton’s Principia (1687). Although written in dense Latin, the Principia – which lays out Newton’s laws of motion and universal gravitation – made a profound impression on her and guided much of her later thinking about celestial mechanics (the study of planetary motion).

Mary Fairfax married twice. Her first marriage (in 1804, at age 24) was to a distant cousin, Captain Samuel Greig of the Russian navy. Greig was not sympathetic to her intellectual interests, complaining “my husband…had a very low opinion of the capacity of my sex.” He died after only three years, leaving Mary a widow with two sons. This freed her to resume serious study. In 1812 she married another cousin, Dr. William Somerville, a physician and the son of her aunt and uncle (Martha and Thomas Somerville). William Somerville deeply respected his wife’s talents and encouraged her learning. In 1816 they moved to London. There she and her husband became part of a scientific circle that included astronomers William and Caroline Herschel, chemist William Hyde Wollaston, physicist Thomas Young, and mathematician Charles Babbage. In London Mary Somerville also tutored Ada Byron (later Ada Lovelace) in mathematics – inspiring Ada’s pioneering work on Charles Babbage’s early mechanical computer.

Together with William, Somerville continued her studies in science. She learned botany and geology at a time when these fields were still new, attending lectures together and examining minerals and fossils. The couple’s social standing and William’s financial stability gave Mary Somerville time and resources for research at a private telescope and in a small home laboratory. By the late 1820s, she had firmly established herself as a rising mathematical writer, preparing to publish her first scientific work.

Major Works and Ideas

Somerville is best known for her books that explained and unified scientific ideas across disciplines. Her writing style was thorough and clear, aimed at explaining advanced concepts to educated readers rather than presenting radically new theories. Key works include:

On the Magnetizing Power of the More Refrangible Solar Rays (1826): This was Somerville’s first scientific paper, published in the Philosophical Transactions of the Royal Society. In it she reported experiments showing that the violet end of the sunlight spectrum can magnetize steel. (In the early 19th century, the solar spectrum was often divided into “rays” by color; the red rays were called “less refrangible” and the violet rays “more refrangible.”) Somerville meticulously exposed steel needles to different colored light and measured small magnetic effects. Her work confirmed earlier Italian experiments and helped demonstrate new connections between light and magnetism. This showed she could conduct original physical experiments, not just mathematics.

On the Mechanism of the Heavens (1831): At the request of scientific activist Henry Brougham, Somerville spent four years translating and condensing Pierre-Simon Laplace’s five-volume Traité de mécanique céleste (1799–1825) on celestial mechanics. Laplace’s original was highly mathematical and written in French. Somerville’s Mechanism of the Heavens presented the same content in English, with additional explanations in easier prose. She carefully organized Laplace’s complex theories of planetary motion and gravity using geometry and algebra. A key part of this book was its Preliminary Dissertation (also published separately in 1832), which summarized the current state of astronomical knowledge for the general reader. For example, she explained Newton’s laws and how they determine the shapes of orbits. British astronomers and mathematicians lauded the result: Mechanism of the Heavens was praised as making celestial mechanics accessible to British science. The Royal Society celebrated the achievement by commissioning a marble bust of Somerville from sculptor Francis Chantrey. The book was even used as a textbook at Cambridge. In modern terms, we might call Mechanism a groundbreaking science-communication effort: it didn’t change the mathematics of Laplace’s theory, but it spread that knowledge widely.

On the Connexion of the Physical Sciences (1834): Somerville’s second book was a broad synthesis of all the sciences she knew. It surveyed astronomy, physics, chemistry, earth sciences, and meteorology (the study of weather and climate), showing how the same physical principles unite them. For example, she discussed how gravity underlies both planetary orbits and ocean tides, how electricity and magnetism are related to light, and how climate depends on atmospheric circulation and solar radiation. Each edition contained revisions as science advanced. The book became extremely popular: it went through eight or nine editions in her lifetime, selling over 15,000 copies. Her clear explanations of new ideas – from spectroscopic chemical analysis to the nature of magnetism – helped educate both scientists and non-specialists. Importantly, Somerville used this book to predict real scientific discoveries. In the third edition (1836) she noted that Uranus’s orbit did not behave exactly as expected from known planets. She suggested that an unknown planet might be perturbing Uranus’s path. This idea caught the attention of British astronomer John Couch Adams, who began calculating the orbit of the hypothetical planet. His calculations, prompted by Somerville’s suggestion, eventually led to rearranging observational schedules and the discovery of Neptune in 1846. Thus Somerville’s exposition directly spurred one of the 19th century’s most famous discoveries.

Physical Geography (1848): Somerville’s third major book was effectively the first English textbook on earth science. In two volumes she described the physical features of the Earth: its shape, structure, landforms, atmosphere, oceans, plants and animals, and human impact on the environment. She treated these topics holistically — for example, she showed how climate is shaped by geography and how human agriculture affects the soil. Her book deliberately ignored political boundaries, viewing Earth as a single system. Somerville wrote this in part to teach science to her own daughter, but it became a towering reference. It went through six editions and was used in schools and universities well into the next century. Her Physical Geography also won the Royal Geographical Society’s prestigious Patron’s Medal in 1869. The award citation noted its wide influence on understanding the planet and life’s place in it.

On Molecular and Microscopic Science (1869): In her late 80s Somerville published a final two-volume work on the very small — the realm of molecules and microscopic organisms. This book reviewed contemporary theories about atoms, molecules, light, heat, and even parasitic organisms. It included discussions of early cell theory and the unseen life forms revealed by microscopes (about 20 years after Pasteur’s experiments). The writing style remained rigorous, though by some accounts this work was less enthusiastic and not as highly regarded as her earlier books. Somerville herself later said that she wondered if she should have devoted that time to pure mathematics, her first love. Still, the book demonstrated her lifelong commitment to surveying the frontiers of science, even in old age.

In addition to her books, Somerville exchanged many letters with scientists in France, England, and Italy. A notable example was a letter to French physicist François Arago (published in Comptes Rendus in 1836) that contained an important observation on magnetism and light. Somerville also left an extensive autobiography, Personal Recollections from Early Life to Old Age (published posthumously in 1873 by her daughter), which is a rich source of her own view of her life and work.

Method

Somerville had no formal research laboratory or university position, so her method was largely independent scholarship. She learned Greek, Latin, French, and German well enough to read original scientific works. Her approach combined meticulous calculation with clear explanation. For instance, in writing Mechanism of the Heavens she worked through Laplace’s algebra and geometry by hand, sometimes re-deriving results in a more understandable order, but always checking each step. She often drew on conversations and correspondence with experts: for example, she consulted Sir John Herschel and François Arago to ensure her summary of celestial mechanics was correct.

As an experimenter, Somerville’s method was careful and inventive. In her 1826 photon–magnetism experiments, she controlled variables (using prisms to split light, shielding parts of her samples, etc.) just as a modern physicist would. In field subjects like geography, she drew on travelers’ reports and foreign language sources to build a global picture. She continually updated her work: every few years she issued a new edition of Connexion, revising chapters on electricity, astronomy, or geology as new discoveries arrived.

Crucially, Somerville’s writing method emphasized exposition. She organized her books thematically, with clear sections and summaries. At the end of each chapter she often recapped the main conclusions. Technical terms (like “celestial mechanics” or “spectroscopy”) were explained in simple language. For an educated but non-specialist audience, she replaced most equations with verbal descriptions or geometric arguments. As a result, contemporaries admired her “exceptional power of exposition.” She made it her goal never to confuse readers: even when describing advanced mathematics, she did so step by step. Her success as a communicator led later scholars to praise her as one of the 19th century’s first great science writers. (Indeed, John Herschel and William Whewell, both key figures in science, acknowledged that Somerville helped synthesize and spread new cosmological ideas through Britain.)

Somerville herself wrote that her strength lay in persistence: if a mathematical problem did not yield on the first try, she would “attack it again on the morrow.” Her intellectual “method” was thus stubborn diligence combined with wide reading. Unlike some scientists who specialized narrowly, she adopted a unified view of science – which became a hallmark of her work. In practice, this meant that when she learned of a new discovery in chemistry or electromagnetism, she immediately thought about how it fit with Earth sciences or astronomy and wove it into her next edition of Connexion. This integrative, cross-disciplinary method made her contributions unique among her peers.

Influence

Somerville’s writings had a broad impact on science and society in her time and after. In science, her clear explanations influenced prominent figures and even guided discovery. The most famous example is the planet Neptune: after Somerville suggested that Uranus’s orbital anomalies pointed to an unseen planet, mathematician John Couch Adams took up the challenge. Adams’s calculations, inspired by her book, directly led to the 1846 observation of Neptune. Her work also impressed later physicists – On the Connexion of the Physical Sciences was cited by James Clerk Maxwell among the “suggestive books” that helped form the ideas used in his own breakthroughs on electricity and magnetism. In fact, Maxwell admired how Somerville put cutting-edge ideas into “intelligible” form for the scientific community. Somerville’s astronomy and physics texts were recommended reading for students and researchers; at Cambridge, Whewell used Mechanism of the Heavens in advanced studies.

She became one of the most famous scientists of her day. In 1835, Queen Victoria’s advisor (Prime Minister Sir Robert Peel) arranged for her to receive a civil pension funded by the government, and it was later raised by another Prime Minister. She and Caroline Herschel were elected honorary members of Britain’s Royal Astronomical Society in 1835 – the first women ever to receive that honor (women were still barred from full fellowship). She was also elected to the Geneva Society of Natural Sciences (1834), the Royal Irish Academy (1834), and later to geographical societies in America and Italy.

Mary Somerville’s influence extended well beyond scientific circles. She was a vocal advocate for women’s rights in education and society. Through her friendship with philosopher John Stuart Mill and others, she helped campaign for women’s suffrage (the vote). Mill placed her name first on the massive 1868 petition to Parliament calling for women’s voting rights. Somerville’s example – a woman achieving international fame in mathematics and astronomy – inspired the Victorian women’s movement. In recognition of her support for women’s education, Somerville College, Oxford (founded 1879) was named in her honor as a pioneering women’s college.

Her peers lavished praise on her multifaceted knowledge. Sir David Brewster, a noted scientist, called Mary Somerville “the most extraordinary woman in Europe – a mathematician of the very first rank.” Another contemporary wrote that her “grasp of scientific truth in all branches” and clarity of explanation made her “the most remarkable woman of her generation.” After her death she was widely remembered as an exemplar of women’s intellectual capabilities. In 2017 she became the first non-royal woman to appear on a new Scottish banknote (the Royal Bank of Scotland’s £10 note), a belated tribute to her role in astronomy and science communication.

Critiques

While Somerville was admired by many, some historians and critics have noted limitations in her work. Unlike Newton or Laplace, Somerville did not introduce a fundamentally new physical theory. Her achievements were chiefly in exposition rather than original research. William Whewell (who coinED the word “scientist”) made this distinction clear in an 1834 review: he praised her philosophical insight but did not label her a “scientist” in the modern sense (the term itself was new). She herself later remarked that she “never made a great discovery” – suggesting that she viewed her role as interpreter and teacher of science.

Modern scholars sometimes point out that calling Somerville’s books “popular” can be misleading. They were far from light reading and were intended for an educated audience. In fact, her works were often heavy, detailed treatises. Unlike today’s popular science writers, Somerville included substantial mathematics and rigorous arguments. This focus on breadth meant she did not delve deeply into one subject. For example, her Physical Geography had to cover so many topics that it could not develop each one as fully as a specialist book might. Critics have observed that this caught her between two worlds: she was not a laboratory scientist gathering new data, yet she was not merely a layperson’s guide. As a result, some contemporaries worried that her books were too advanced for casual readers (British publisher Henry Brougham initially thought Mechanism of the Heavens was too long and difficult for working-class education).

Even Somerville herself wondered if some of her later work missed the mark. After her Molecular and Microscopic Science appeared, she reportedly mused that perhaps she should have devoted more time to pure mathematics – her first passion – rather than straying into biology and speculation in her eighties. Nonetheless, such self-critiques are minor compared to her overall contributions. Today historians generally view Somerville as a serious scientist in her own right, even if her achievements were of the “synthesizer” kind rather than inventing new laws of nature.

Legacy

Mary Somerville’s legacy lies in science communication, women’s education, and honorific memorials. Somerville College (Oxford) remains a leading college for women (and now men) scholars, named to honor her commitment to women’s access to learning. She appears on postage stamps, banknotes, and medals. For example, the Royal Society of Edinburgh (Scotland) inaugurated a Mary Somerville Medal (from 2022) recognizing collaborative research, highlighting her esteem in her homeland. A lunar crater on the Moon is named Somerville, ensuring her name is literally among the stars.

Statues and busts of Somerville have been erected. The Royal Society of London has a marble bust of her in its halls (commissioned in 1839), and portraits of her hang in learned institutions. Many universities and scientific organizations hold collections of her letters and use her life story to teach about women in science.

In science history and education she remains a popular figure. Textbooks on the history of astronomy and physics often mention “Somerville’s The Mechanism of the Heavens” as a milestone in 19th-century science. Biology and earth science teachers may recall that her Physical Geography was foundational. Over a century after her death, scholars continue to reassess her work. James Secord, a science historian, emphasizes that Somerville challenged the entrenched view that women could not do serious science; she showed instead that a talented woman could rank among the intellectual leaders of an era.

Even today, Mary Somerville is remembered not only for the facts she recorded but for the method she represented: passionate, disciplined self-study and a belief in a unified science. Her name symbolizes the importance of clear explanation and the power of perseverance. As one modern writer put it, Somerville “deserves her place” on any list of great scientists (and indeed was once called “Queen of Science”). Through her books, her advocacy, and the institutions that bear her name, her influence endures as a role model for scientists and educators, women and men alike.

Selected Works

On the Magnetizing Power of the More Refrangible Solar Rays (paper, 1826) – Report of Somerville’s experiments showing that violet sunlight can magnetize steel. (Philosophical Transactions of the Royal Society.)
On the Mechanism of the Heavens (book, 1831) – English treatise based on Laplace’s Mécanique céleste, explaining celestial mechanics and summarizing the solar system’s physics. Includes the Preliminary Dissertation of 1832 (an overview of astronomy).
On the Connexion of the Physical Sciences (book, 1834) – An interdisciplinary survey of astronomy, physics, chemistry, geology, and meteorology. Went through eight editions (last in 1875).
Physical Geography (2 volumes, 1848) – A comprehensive work on earth sciences, climate, and the natural environment; a standard textbook of its time.
On Molecular and Microscopic Science (2 volumes, 1869) – Somerville’s final book, on atoms, molecules, light, and microscopic life. It was the culmination of her lifelong interest in the smallest scales of nature.
Personal Recollections from Early Life to Old Age of Mary Somerville (autobiography, 1873) – Written by Somerville and edited by her daughter, this volume recounts her experiences and thoughts in her own voice.

Sources: This account is based on biographical and historical sources, including the biographies in Encyclopædia Britannica and the MacTutor History of Mathematics archive, contemporary reviews, Somerville’s own writings, and modern histories of science. The material has been synthesized from authoritative references on Somerville’s life and work.