Thor Deity, common to all the early as a great, red-bearded warrior of tre¬ mendous strength. The son of Odin ( according to some legends) and Jord, the earth goddess, he was the implacable foe of the harmful race of giants but was benevolent toward humans. His name is the Germanic word for thunder. His great weapon was his hammer, Mjollnir. His great¬ est enemy was the world serpent Jor- mungand, which he was destined to kill, and be killed by, in the Rag- narok. Thursday is named for Thor.
Thor rocket Missile initially devel¬ oped by the U.S. Air Force as an intermediate-range ballistic missile.
It became operational in 1958 and was later modified to serve as the first stage of launch vehicles for sev¬ eral spacecraft. The Thor missile force was withdrawn in 1963. For space launching, three small auxil¬ iary motors were strapped to a Thor rocket, and this resulted in a thrust nearly twice as powerful as the origi¬ nal.
thoracic \th9-'ra-sik\ cavity or chest cavity Second largest hollow space of the body, enclosed by the ribs, vertebral column, and breastbone and separated from the abdominal cavity by the diaphragm. It contains the lungs and bronchi, part of the esophagus and trachea, and the heart and
major blood vessels. A membrane called the pleura lines the cavity (pari¬ etal pleura) and continues over the lung (visceral pleura) and the rest of the cavity’s contents, defining a space called the mediastinum. Disorders include blood (hemothorax) or air (pneumothorax, which can lead to atelectasis) in the pleural cavity and inflammation of the pleura (pleurisy).
Thoreau \th3-'ro\, Henry David (b. July 12, 1817, Concord, Mass., U.S.—d. May 6, 1862, Concord)
U.S. thinker, essayist, and naturalist.
Thoreau graduated from Harvard University and taught school for sev¬ eral years before leaving his job to become a poet of nature. Back in Concord, he came under the influ¬ ence of Ralph Waldo Emerson and began to publish pieces in the Tran- scendentalist magazine The Dial. In the years 1845-47, to demonstrate how satisfying a simple life could be, he lived in a hut beside Concord’s Walden Pond; essays recording his daily life were assembled for his masterwork, Walden (1854). His A Week on the Concord and Merrimack Rivers (1849) was the only other book he published in his lifetime. He reflected on a night he spent in jail protesting the Mexican-American War in the essay “Civil Disobedi¬ ence” (1849), which would later influence such figures as Mohandas K. Gandhi and Martin Luther King, Jr. In later years his interest in Tran¬ scendentalism waned, and he became a dedicated abolitionist. His many nature writings and records of his wanderings in Canada, Maine, and Cape Cod display the mind of a keen naturalist. After his death his collected writings were published in 20 volumes, and further writings have contin¬ ued to appear in print.
Thorez \to-'rez\, Maurice (b. April 28, 1900, Noyelles-Godault, France—d. July 11, 1964, at sea en route to Yalta) French communist politician. He began working as a coal miner at age 12. He joined the French Communist Party c. 1920 and was arrested several times for agita¬ tion. After becoming local party secretary (1923), he rose to secretary- general of the party (1930). He served in the Chamber of Deputies (1932- 39, 1945-60) and helped form the Popular Front government in 1936. He lived in the Soviet Union (1943-44), then returned to France and served as a minister of state (1945) and deputy premier (1946, 1947). He remained a dedicated Stalinist even after Nikita Khrushchev denounced Joseph Stalin in 1956.
thorium Metallic chemical element, chemical symbol Th, atomic num¬ ber 90. One of the actinide series of elements, natural thorium is a mix¬ ture of radioactive isotopes, predominantly thorium-232 (half-life of more than 10 billion years). It is a dense metal that is silver-white in pure form but turns gray or black on prolonged exposure to air. Although not a nuclear reactor fuel itself, thorium-232 can be used in breeder reactors because, on capturing slow-moving neutrons, it decays into fissionable uranium-233. Thorium is added to magnesium and its alloys to improve their high-temperature strength. Added to glass, it yields glasses with a high refractive index, useful for specialized optical applications. It was formerly in great demand as a component of mantles for gas and kero¬ sene lamps and has been used in the manufacture of tungsten filaments for lightbulbs and vacuum tubes.
Thorndike, Edward L(ee) (b. Aug. 31, 1874, Williamsburg, Mass., U.S.—d. Aug. 9, 1949, Montrose, N.Y.) U.S. psychologist. He trained under William James and James McKeen Cattell and later taught at Colum¬ bia University (1904^-0). A pioneer in the fields of animal learning and educational psychology, he developed a form of behaviourism known as connectionism, which holds that learning takes place through associative bonds. He contributed significantly to the development of quantitative experimental methods and to more efficient and scientifically based meth¬ ods of teaching. Among his writings are Introduction to the Theory of Mental and Social Measurements (1904), Principles of Teaching Based on Psychology (1906), Animal Intelligence (1911), and The Psychology of Wants, Interests, and Attitudes (1935).
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Thor with his hammer, Mjollnir, on his knees, bronze statuette from northern Iceland, c. ad 1000; in the National Museum of Iceland, Reykjavik.
COURTESY OF THE NATIONAL MUSEUM OF ICELAND, REYKJAVIK
Henry David Thoreau, portrait by Sam¬ uel Worcester Rowse, 1854; in the Concord Free Public Library, Massa¬ chusetts.
COURTESY OF THE CORPORATION OF THE FREE PUBUC LIBRARY, CONCORD, MASS.
© 2006 Encyclopaedia Britannica, Inc.
Thorndike ► thread cross I 1903
Thorndike, Dame (Agnes) Sybil (b. Oct. 24, 1882, Gainsborough, Lincolnshire, Eng.—d. June 9, 1976, London) British actress. As a mem¬ ber of the Old Vic company in London (1914-18), she became a leading tragic actress. Noted for her versatility in modem and classic plays, she originated the title role in George Bernard Shaw’s Saint Joan (1924). She managed several London theatres, and she often costarred with her hus¬ band, the actor-director Lewis Casson, in her more than five decades in the theatre.
Thoroughbred Light breed of racing and jumping horse descended from three desert stallions brought to England between 1689 and 1724. Thoroughbreds have a delicate head, slim body, broad chest, and short back. Most are bay, chestnut, brown, black, or gray. They stand about 16 hands (64 in., 163 cm) high and weigh about 1,000 lbs (450 kg). They are sensitive and high-spirited and are often used to improve other stock.
Thorp, John (b. 1784, Rehoboth, Mass., U.S.—d. Nov. 15, 1848, Provi¬ dence, R.I.) U.S. inventor. He invented the ring spinning machine in 1828. By the 1860s it had largely replaced Samuel Crompton’s spinning mule in the world’s textile mills because of its greater productivity and simplicity.
Thorpe, Jim in full James Francis Thorpe (b. May 28, 1888, near Prague, Indian Territory—d. March 28, 1953, Lomita, Calif., U.S.) U.S. athlete. Of predominantly American Indian (Sauk and Fox) descent, he trained as a football halfback under Pop Warner while attending the Indian Industrial School in Carlisle,
Pa. (1908-12), where he also excelled at baseball, basketball, box¬ ing, lacrosse, swimming, and hockey. In 1912 he won the Olympic decathlon and pentathlon by wide margins, but he was deprived of his medals in 1913 after it was discov¬ ered he had played semiprofessional baseball. He later played profes¬ sional baseball and football, and in 1920-21 he served as first president of what would become the National Football League. His Olympic medals were restored posthumously in 1983.