SOMERVILLE, MARY (1780–1872), British scientific writer, was the daughter of Admiral Sir William George Fairfax, and was born on the 26th of December 1780 in the manse of Jedburgh, the house of her mother’s sister, wife of Dr Thomas Somerville (1741–1830), author of My Own Life and Times, whose son was her second husband. She received a rather desultory education, and mastered algebra and Euclid in secret after she had left school, and without any extraneous help. In 1804 she married her cousin, Captain Samuel Greig, who died in 1806; and in 1812 she married another cousin, Dr William Somerville (1771–1860), inspector of the army medical board, who encouraged and greatly aided her in the study of the physical sciences. After her marriage she made the acquaintance of the most eminent scientific men of the time, among whom her talents had attracted attention before she had acquired general fame, Laplace paying her the compliment of stating that she was the only woman who understood his works. Having been requested by Lord Brougham to translate for the Society for the Diffusion of Useful Knowledge the Mécanique Céleste of Laplace, she greatly popularized its form, and its publication in 1831, under the title of The Mechanism of the Heavens, at once made her famous. Her other works are the Connexion of the Physical Sciences (1834), Physical Geography (1848), and Molecular and Microscopic Science (1869). Much of the popularity of her writings was due to their clear and crisp style and the underlying enthusiasm for her subject which pervaded them. In 1835 she received a pension of £300 from government. She died at Naples on the 28th of November 1872. In the following year there appeared her Personal Recollections, consisting of reminiscences written during her old age, and of great interest both for what they reveal of her own character and life and the glimpses they afford of the literary and scientific society of bygone times.