Mary Somerville, a British physicist, born in Jedburgh, Roxburghshire, Scotland, Dec. 26, 1780, died in Naples, Italy, Nov. 29, 1872. She was the daughter of Vice Admiral Sir William Fairfax, and chiefly through her own efforts acquired a thorough education, particularly in mathematics and landscape painting. In 1804 she married Samuel Greig, then Russian consular agent in London, where she went to reside. Left a widow in 1807, she returned to Edinburgh, and in 1812 married her cousin "William Somerville, M. D., who in 1816 was appointed a member of the army medical board, and removed to London. Here she attracted attention by some experiments on the magnetic influence of the violet rays in the solar spectrum, the results of which were published in the "Philosophical Transactions" of 1826; and Lord Brougham suggested that she should prepare for the " Library of Useful Knowledge " a summary of the Mecca-nique celeste of Laplace, which proved too voluminous for its original destination, and was published under the title "Mechanism of the Heavens" (8vo, Cambridge, 1831). This work led to her election as an honorary member of the royal astronomical society, and her bust by Chantrey was placed in their hall.

In 1834 she published "The Connection of the Physical Sciences" (9th ed., 1858). In 1835 she received a pension of £200, subsequently increased to £300. Soon afterward she went to Italy on account of the health of her husband, and there resided during the rest of her life, principally in Florence, Rome, and Naples. Her next work was "Physical Geography " (2 vols., 1848; 6th ed., 1870), a history of the earth in its whole material organization, and of animal and vegetable life; and her last, "Molecular and Microscopic Science" (2 vols., 1869). She was a member of many foreign societies, and in 1869 received the Victoria medal of the royal geographical society, and in the same year the first gold medal ever awarded by the Italian geographical society. She warmly favored what are popularly known as "women's rights," and was a member of the general committee for woman suffrage in London. In her 92d year she read books in the higher mathematics four or five hours daily, solved the problems, and to the day of her death was occupied in the revision and completion of a treatise on the "Theory of Differences." During her last few years she noted down some recollections of her life, which have been published under the title "Personal Recollections, from Early Life to Old Age, of Mary Somerville," by her daughter, Martha Somerville (8vo, London, 1873).