Graves, Robert (von Ranke) (b. July 24/26, 1895, London, Eng.—d. Dec. 7, 1985, Deya, Majorca, Spain) British man of letters. He served as an officer at the Western Front during World War I and his first three volumes of poetry were published during that time; they include some of the finest English love poems of the century. In 1926 he began a 13-year relationship with the American poet Laura Riding (1901-91), with whom he founded a press, briefly published a journal, and collabo¬ rated as a writer. After 1929 he lived principally in Majorca, Spain. The most famous of his more than 120 books are Good-bye to All That (1929), a grim memoir of the war; the historical novel I, Claudius (1934; tele¬ vised in 1976); and erudite, controversial studies in mythology, notably The White Goddess (1948).
Graves, Robert James (b. 1796, Dublin, Ire.—d. March 20, 1853, Dublin) Irish physician. In 1821 he set up the Park Street School of Medi¬ cine, where he gave his advanced students responsibility for patients (under supervision) and lectured in English, not Latin. He was a founder
Short-horned grasshopper (Acrididae)
EARL L. KUBIS-ROOT RESOURCES
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Graves disease ► Great Attractor I 793
and editor of the Dublin Journal of Medical Science. His Clinical Lec¬ tures on the Practice of Medicine (1848) established his reputation. He introduced timing of the pulse by watch and giving patients with fevers nourishment instead of withholding it. He was a leader of the Irish (Dub¬ lin) school of diagnosis, which stressed observation of patients, and was one of the first to fully describe exophthalmic goitre (Graves disease).
Graves disease or toxic diffuse goitre or exophthalmic
\,ek-saf-'thal-mik\ goitre Most common type of hyperthyroidism (over¬ secretion of thyroid hormone), usually with goitre and exophthalmos (eye¬ ball protrusion). Increased thyroid hormone levels result in increased cardiac output, rapid heartbeat, and possibly heart failure. Stress may trigger a severe worsening (thyroid storm), which can lead to circulatory collapse and death. Graves disease is considered an autoimmune disease. It can sometimes be controlled by drugs; severe cases require partial or total removal of the thyroid gland. Graves disease is named after Robert James Graves, one of the first physicians to fully describe the disease.
gravitation Universal force of attraction that acts between all bodies that have mass. Though it is the weakest of the four known forces, it shapes the structure and evolution of stars, galaxies, and the entire universe. The laws of gravity describe the trajectories of bodies in the solar system and the motion of objects on Earth, where all bodies experience a downward gravitational force exerted by Earth’s mass, the force experienced as weight. Isaac Newton was the first to develop a quantitative theory of gravitation, holding that the force of attraction between two bodies is pro¬ portional to the product of their masses and inversely proportional to the square of the distance between them. Albert Einstein proposed a whole new concept of gravitation, involving the four-dimensional continuum of space-time which is curved by the presence of matter. In his general theory of relativity, he showed that a body undergoing uniform acceleration is indistinguishable from one that is stationary in a gravitational field.
gravitational radius See Schwarzschild radius
gravity, centre of Imaginary point where the total weight of a mate¬ rial body may be thought to be concentrated. Since weight and mass are proportional, the same point may also be called the centre of mass, but the centre of mass does not require a gravitational field. A body’s centre of gravity may coincide with its geometric centre, especially if the body is symmetric and composed of homogeneous material. In asymmetric, unhomogeneous, or hollow objects, the centre of gravity may be at some distance from the geometric centre or even at a point in space external to the object, such as between the legs of a chair.
gravure \gr3-'vyur\ printing Printing processes used for catalogs, magazines, newspaper supplements, cartons, floor and wall coverings, textiles, and plastics. The Bohemian Karel Klfc made photogravure a practical commercial process in 1878. An image is etched in the copper surface of the printing cylinder as pits or wells of different depths. In rotogravure printing, the cylinder rotates through a trough filled with fast¬ drying ink. A thin steel doctor blade removes the ink from the surface but not from the wells. The cylinder comes in contact with the paper, which draws the ink out of the wells. Because of the various depths of the wells, a full range of tonal values can be printed; in reproducing illustrations, gravure comes closest to simulating continuous-tone copy. In colour print¬ ing, a separate cylinder is prepared for each colour. See also letterpress printing; offset printing.
Gray, Asa (b. Nov. 18, 1810, Sauquoit, N.Y., U.S.—d. Jan. 30, 1888, Cambridge, Mass.) U.S. botanist. He received a medical degree from Fairfield Medical School, where he spent his spare time studying plant specimens. He collaborated with John Torrey (1796-1873) on Flora of North America (1838^13) and in 1842 joined the faculty at Harvard Uni¬ versity, where he would teach until 1873. His donation of his thousands of books and plant specimens established Harvard’s botany department. Gray was largely responsible for the unification of the taxonomic knowl¬ edge of the North American flora; his most widely used book, commonly called Gray’s Manual (1848), remains a standard work. He was the chief early American supporter of the theories of Charles Darwin.
Gray, Thomas (b. Dec. 26, 1716, London, Eng.—d. July 30, 1771, Cambridge, Cambridgeshire) British poet. He studied and later settled at Cambridge, where he wrote poems of wistful melancholy filled with tru¬ isms phrased in striking, quotable lines. Though his output was small, he became the dominant poetic figure in his day. He is remembered espe¬ cially for “An Elegy Written in a Country Church Yard” (1751), one of
the best known of English lyric poems and the greatest work of the English “graveyard school.” After its overwhelming success, his next two poems met a disappointing response, and he virtually ceased writing.
gray fox Grizzled, gray-furred New World FOX ( Urocyon cinereoar- genteus) found in forested, rocky, and brush-covered country from Canada to northern South America.
Distinguished by the reddish color on its neck, ears, and legs, it grows to a length of about 20-30 in. (50-75 cm), excluding its 12-16-in. (30^10- cm) tail, and a weight of about 7-13 lbs (3-6 kg). Unlike other foxes, it commonly climbs trees. Primarily nocturnal, it takes a variety of foods, including small birds and mammals, insects, and fruits.
gray hound See greyhound
grayling Any of several game fishes (genus Thymallus), similar to trout, that are found in cold, clear streams of Eurasia and northern North America. Graylings are silvery purple and reach a length of about 16 in. (40 cm). They have relatively large scales, a small mouth with weak teeth, and a sail-like, brightly coloured dorsal fin. They feed primarily on insects and spawn in shallow water in the spring. Pollution of streams has reduced the numbers of this excellent food fish.