Mary Somerville was the daughter of William George Fairfax and his second wife Margaret Charters. Mary Fairfax was born in the church manse in Jedburgh, the home of her mother's sister Martha Charters and Martha's husband Thomas Somerville. Mary's father was a naval officer, later Vice-Admiral Sir William George Fairfax, who was at sea at the time of her birth. Mary's mother had visited London from where her husband embarked on a long sea voyage. Margaret Fairfax broke her journey north at Jedburgh where Mary was born. The family home was in Burntisland in the county of Fife, Scotland.
Mary was the fifth of seven children but three died very young. Of the four remaining children, Mary was brought up with her brother who was three years older than she was. A sister was born when Mary was seven, and a second brother when she was ten. The two brothers were given a good education but, in keeping with the ideas of the time, little need was seen to educate girls so Mary's parents saw no need to provide an education for their daughter. As a young child what little education she did receive was from her mother who taught her to read but it was not considered necessary to teach her to write. When Mary was ten years old she was sent to Miss Primrose's boarding school for girls in Musselburgh (a few miles east of Edinburgh on the Firth of Forth). Burntisland and Musselburgh are on opposite sides of the Firth of Forth, Burntisland on the north, Musselburgh on the south.
The school in Musselburgh neither gave Mary a happy time nor a good education. Anyway she spent only one year there and, on leaving felt (in her own words) (see  or ):-
... like a wild animal escaped out of a cage.
After this Mary returned to her home in Burntisland but she began to educate herself by reading every book that she could find in her home. Far from being encouraged in reading, members of her family such as her aunt criticised her for spending time on this unladylike occupation. In order that she might learn the correct skills for a young lady, Mary was sent to a school in Burntisland where she was taught needlework.
However, one member of Mary's family did encourage her with her educational ambitions. When visiting her uncle in Jedburgh Mary told him that she had been teaching herself Latin. Far from being cross, her uncle encouraged her and the two would read Latin before breakfast while Mary stayed in the Jedburgh manse.
When Mary was about thirteen, the family rented a house in Edinburgh where they spent the winter months, the summers being spent in Burntisland. Mary balanced her life between the social life expected of a young lady at this time and her own private study. She did learn many skills that were seen appropriate for a young lady. In addition to the needlework mentioned above, she learnt to play the piano and was given lessons in painting from the artist Alexander Nasmyth.
In fact it was through Nasmyth that Mary first became interested in mathematics. She overheard him explaining to another pupil that Euclid's Elements formed the basis for understanding perspective in painting, but much more, it was the basis for understanding astronomy and other sciences. This comment was enough to start Mary on the road to study Euclid's Elements which she did with the help of her younger brother's tutor.
There was another quite different reason why Mary became interested in studying algebra. She read an article on the subject in a woman's magazine belonging to a friend. Her younger brother's tutor was able to provide Mary with algebra texts and help introduce her to the subject. Mary became so engrossed in mathematics that her parents worried that her health would suffer because of the long hours of study that she put in, usually during the night. Her father believed (as was common at the time) that :-
... the strain of abstract thought would injure the tender female frame.
Social life in Edinburgh was strongly encouraged, however, where Mary enjoyed :-
... parties, visits, balls, theatres, concerts, and innocent flirtations ...
Mary married Samuel Greig in 1804 when she was 24 years old. Her husband was a naval officer who was a distant relation on her mother's side of the family (Samuel Greig's father was a nephew of Mary's maternal grandfather). However Samuel was in the Russian navy and Mary's parents did not allow the marriage to take place until Greig received an appointment in London, for they did not want Mary to go to Russia. Mary and Samuel Greig went to London but Mary found that her husband did not understand her desires to learn. She later wrote (see  or ):-
He had a very low opinion of the capacity of my sex, and had neither knowledge of, nor interest in, science of any kind.
Samuel Greig died 3 years after the marriage. By this time Mary had given birth to two sons and on the death of her husband she returned to Scotland with them. She now had a circle of friends who strongly encouraged her in her studies of mathematics and science. In particular John Playfair, then professor of natural philosophy at Edinburgh, encouraged her and through him she began a correspondence with William Wallace (Playfair's former pupil) who was then professor of mathematics at the Royal Military College at Great Marlow. In this correspondence they discussed the mathematical problems set in the Mathematical Repository and in 1811 Mary received a silver medal for her solution to one of these problems. At this time Mary also read Newton's Principia and, at Wallace's suggestion, Laplace's Mécanique Céleste and many other mathematical and astronomical texts.
In 1812 Mary Greig married William Somerville who was an inspector of hospitals. William was the son of her aunt Martha and her husband Thomas Somerville in whose manse she had been born. Unlike her first husband, William was interested in science and also supportive of his wife's desire to study. At this time William and Mary lived in Edinburgh and, advised by Wallace, Mary read the most advanced French texts of the day. In addition she studied botany and improved her knowledge of Greek. With her husband she studied geology and they moved in a close circle of friends that included Playfair, Leslie, Sir William Scott, and the physicist David Brewster.
In 1814 Mary's oldest daughter from her first marriage died at the age of nine and, in the same year, the only son of her second marriage died as a baby.
When William Somerville was appointed as Inspector to the Army Medical Board in 1816, the family moved from Edinburgh to London. Mary's husband was elected to the Royal Society and Mary and William moved in the leading scientific circles of the day. Their friends included George Airy, John Herschel, William Herschel, George Peacock, and Charles Babbage. Mary wrote :-
We frequently went to see Mr Babbage while he was making his calculating machines.
In addition they met with leading European scientists and mathematicians who visited London. In 1817 William and Mary visited Paris and were introduced to the leading scientists there by Biot and Arago (whom they had met in London). Mary met Laplace, Poisson, Poinsot, Émile Mathieu and many others. Returning to London, Mary and William lived in central London which enabled them to continue close contact with their many scientific friends. In 1824 William was appointed as a physician at the Royal Hospital in Chelsea, and the family moved to Chelsea, then on the edge of London.
Mary Somerville published her first paper The magnetic properties of the violet rays of the solar spectrum in the Proceedings of the Royal Society in 1826. The paper :-
... showed ingenuity in original speculation, and attracted much interest at the time, although the theory it propounded was subsequently negatived ...
In 1827 Lord Brougham made a request on behalf of the Society for the Diffusion of Useful Knowledge for Mary Somerville to translate Laplace's Mécanique Céleste. However Mary went far beyond a translation, for she explained in detail the mathematics used by Laplace which was unfamiliar to most mathematicians in England at that time. When completed, the work with title The Mechanism of the Heavens was far too large to be published by the Society for the Diffusion of Useful Knowledge and John Herschel recommended its publication to the publisher John Murray. The book appeared in 1831 and was an immediate success both in terms of the number of copies sold and the praise given to it. Also in 1831 James David Forbes, later to become the Principal of the University of St Andrews, was in London and wrote in his notebook his impressions of Mary:-
Below middle size, fair, countenance not particularly expressive except eyes which are piercing. Short-sighted. Manners the simplest possible. Her conversation very simple and pleasing. Simplicity not showing itself in abstaining from scientific subjects with which she is so well acquainted, but in being ready to talk on them all with the naiveté of a child and the utmost apparent unconsciousness of the rarity of such knowledge as she possesses, so that it requires a moment's reflection to be aware that one is hearing something very extraordinary from the mouth of a woman.
Mary Somerville spent about a year abroad in 1832-33. Most of the time was spent in Paris where she renewed old friendships with the mathematicians there, and where she worked on her next book The connection of the physical sciences which was published in 1834. Her discussion of a hypothetical planet perturbing Uranus in the sixth edition (1842) of this work led Adams to his investigation and subsequent discovery of Neptune.
Another friend of the family was Lady Byron, by this time estranged from her husband Lord Byron, and her daughter Ada Lovelace. Back in London, Mary helped Ada in her study of mathematics and provided strong encouragement to her.
Honours now come quickly to Mary Somerville. She was elected to the Royal Astronomical Society in 1835 (at the same time as Caroline Herschel). She was elected to honorary membership of the Société de Physique et d'Histoire Naturelle de Genève in 1834 and, in the same year, to the Royal Irish Academy. Sir Robert Peel, British prime minister from 1834-35 and again from 1841-46, awarded her a civil pension of £200 per annum, during his first period of office. This was increased to £300 in 1837 by William Lamb, 2nd Viscount Melbourne (British prime minister from 1835-41).
A letter which Mary wrote to Arago contained information important enough for him to have an extract from the letter published as a paper in Comptes Rendus in 1836. In 1838 William Somerville's health deteriorated and the family went to Italy. (William survived for 22 further years there.) Most of the rest of Mary's life was spent in Italy where she wrote many works which influenced Maxwell. Most important of her later publications was Physical geography which was published in 1848. It was her most successful text and used until the beginning of the 20th century in schools and universities.
Many further honours were given to Mary as a result of this publication. She was elected to the American Geographical and Statistical Society in 1857 and the Italian Geographical Society in 1870. Also in 1870 she received the Victoria Gold Medal of the Royal Geographical Society.
Mary Somerville was a strong supporter of women's education and women's suffrage. When John Stuart Mill, the British philosopher and economist, organised a massive petition to parliament to give women the right to vote, he had Mary put her signature first on the petition. Somerville College in Oxford was named after her in 1879 because of her strong support for women's education.
Many tributes to Mary Somerville sum up her contribution. From :-
Her grasp of scientific truth in all branches of knowledge, combined with an exceptional power of exposition, made her the most remarkable woman of her generation.
Sir David Brewster, inventor of the kaleidoscope, wrote in 1829 (nine years before becoming Principal of the University of St Andrews) that Mary Somerville was:-
... certainly the most extraordinary woman in Europe - a mathematician of the very first rank with all the gentleness of a woman ... She is also a great natural philosopher and mineralogist.
Let us end this biography with Mary Somerville's own words, written late in her life :-
Sometimes I find [mathematical problems] difficult, but my old obstinacy remains, for if I do not succeed today, I attack them again on the morrow.
Article by: J J O'Connor and E F Robertson