Encyclopædia Britannica Australia -

Encyclopedias since 1768

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thermistor ... Thies

thermistor: electrical-resistance element made of a semiconducting material consisting of a mixture of oxides of manganese and nickel; its resistance varies with temperature. Thermistors (temperature-sensitive, or thermal, resistors) are used as temperature-measuring devices and in electrical circuits to compensate for temperature ...
Thermit: powdered mixture used in incendiary bombs, in the reduction of metals from their oxides, and as a source of heat in welding iron and steel and in foundry work.
thermocline: oceanic water layer in which water temperature decreases rapidly with increasing depth. A widespread permanent thermocline exists beneath the relatively warm, well-mixed surface layer, from depths of about 200 m (660 feet) to about 1,000 m (3,000 feet), in which ...
thermocouple: a temperature-measuring device consisting of two wires of different metals joined at each end. One junction is placed where the temperature is to be measured, and the other is kept at a constant lower temperature. A measuring instrument is connected ...
thermodynamic equilibrium: condition or state of a thermodynamic system, the properties of which do not change with time and that can be changed to another condition only at the expense of effects on other systems. For a thermodynamic equilibrium system with given ...
thermodynamics: systematic study of the relationship between heat, work, temperature, and energy, now encompassing the general behaviour of physical systems in a condition of equilibrium or close to it. It is a fundamental part of all the physical sciences.
thermoelectric power generator: any of a class of devices that either convert heat directly into electricity or transform electrical energy into pumped thermal power for heating or cooling. Such devices are based on thermoelectric effects involving interactions between the flow of heat and ...
thermokarst: land-surface configuration that results from the melting of ground ice in a region underlain by permafrost. In areas that have appreciable amounts of ice, small pits, valleys, and hummocks are formed when the ice melts and the ground settles unevenly. ...
thermoluminescence: emission of light from some minerals and certain other crystalline materials. The light energy released is derived from electron displacements within the crystal lattice of such a substance caused by previous exposure to high-energy radiation. Heating the substance at temperatures ...
thermometry: the science of measuring the temperature of a system or the ability of a system to transfer heat to another system. Temperature measurement is important to a wide range of activities, including manufacturing, scientific research, and medical practice.
thermonatrite: a carbonate mineral, hydrated sodium carbonate (Na₂CO₃·H₂O), found near saline lakes as an evaporation product or on arid soil as an efflorescence. It is usually associated with natron (Na₂CO₃·10H₂O) and trona, which alter to it upon partial dehydration; many reported ...
thermonuclear bomb: weapon whose enormous explosive power results from an uncontrolled, self-sustaining chain reaction in which isotopes of hydrogen combine under extremely high temperatures to form helium in a process known as nuclear fusion. The high temperatures that are required for the ...
thermonuclear reaction: fusion of two light atomic nuclei into a single heavier nucleus by a collision of the two interacting particles at extremely high temperatures, with the consequent release of a relatively large amount of energy. Chains of thermonuclear reactions, such as ...
thermoperiodicity: the growth or flowering responses of plants to alternation of warm and cool periods. Daily temperature fluctuations produce dramatic effects on the growth or flowering of most plants. The lack of lower night temperatures frequently results in poor growth, as ...
Thermopolis: resort town, seat (1913) of Hot Springs county, north-central Wyoming, U.S., on the Bighorn River, opposite East Thermopolis. The site was originally within the Wind River Indian Reservation (Shoshone and Arapaho). Founded in 1897, its name was derived from the ...
Thermopylae: narrow pass on the east coast of central Greece between the Kallidhromon massif and the Maliakos Gulf, about 85 miles (136 km) northwest of Athens. In antiquity its cliffs were by the sea, but silting has widened the distance to ...
thermoreception: process in which different levels of heat energy (temperatures) are detected by living things.
thermoregulation: the maintenance of an optimum temperature range by an organism. Cold-blooded animals (poikilotherms) pick up or lose heat by way of the environment, moving from one place to another as necessary. Warm-blooded animals (homoiotherms) have additional means by which they ...
thermosphere: region of increasing temperature above the mesosphere. The base of the thermosphere (the mesopause) is at an altitude of about 80 km (50 miles), whereas its top (the thermopause) is at about 450 km.
thermostat: device to detect temperature changes for the purpose of maintaining the temperature of an enclosed area essentially constant. In a system including relays, valves, switches, etc., the thermostat generates signals, usually electrical, when the temperature exceeds or falls below the ...
theropod: any member of the dinosaur subgroup, Theropoda, that includes all the flesh-eating dinosaurs. Theropods were the most diverse group of saurischian ("lizard-hipped") dinosaurs, ranging from the crow-sized Microraptor to the huge Tyrannosaurus rex, which ...
Theroux, Paul: American novelist and travel writer known for his highly personal observations on many locales.
Thesaurus Linguae Latinae: dictionary of the Latin language, published at Leipzig, the most important and definitive such undertaking of modern times. It is being prepared by the Universities of Berlin, Gottingen, Leipzig, and Munich in Germany and by Vienna University in Austria.
Thesavalamai: traditional law of the Tamil country of northern Sri Lanka, codified under Dutch colonial rule in 1707. The Dutch, to facilitate the administration of their colonial territories in Ceylon, established there an elaborate system of justice based on Roman-Dutch law ...
Theseum: temple in Athens dedicated to Hephaestus and Athena as patrons of the arts and crafts. Its style indicates that this, the best-preserved ancient Greek temple in the world, is slightly older than the Parthenon (i.e., c. 450-440 BC), and the ...
Theseus: great hero of Attic legend, son of Aegeus, king of Athens, and Aethra, daughter of Pittheus, king of Troezen (in Argolis), or of the sea god, Poseidon, and Aethra. Legend relates that Aegeus, being childless, was allowed by Pittheus to ...
Thesmophoria: in Greek religion, ancient festival held in honour of Demeter Thesmophoros and celebrated by women in many parts of the Greek world. The meaning of the name Demeter Thesmophoros still remains a matter of disagreement, although a possible translation is ...
Thespiae: ancient Greek city of Boeotia by the Thespius (modern Kanavari) River and at the eastern foot of Mt. Helicon; site of the "Eros" of Praxiteles, one of the most famous statues in the ancient world, and home of the sanctuaries ...
Thespis: Attic Greek poet from the deme (district) of Icaria who reputedly originated the actor's role in drama. He was often considered the "inventor of tragedy," and his name is recorded as the first to win a prize for tragedy at ...
Thessalonians, letters of Paul to the: two New Testament letters written by Paul from Corinth, Greece, about AD 50 and addressed to the Christian community he had founded in Macedonia.
Thessaloniki: city, capital and residence of the minister for northern Greece and administrative centre of the nomos (department) of Thessaloniki, on the west side of the Chalcidice (Khalkidhiki) peninsula at the head of a bay on the Thermaikos Kolpos (Gulf of ...
Thessaly: region of northern Greece south of Macedonia, lying between upland Epirus and the Aegean Sea and comprising chiefly the fertile Trikala and Larissa lowlands. It is well delineated by topographical boundaries: the Khasia and Cambunian mountains (north), the Othris massif ...
Thetford: town ("parish"), Breckland district, administrative and historic county of Norfolk, England. The town lies on the edge of Thetford Chase Forest. It possesses the remains of a Cluniac priory, a Benedictine nunnery, and a large medieval mound known as Castle ...
Thetford-Mines: city, Chaudiere-Appalaches region, southern Quebec province, Canada. Originating after the discovery of asbestos deposits there in 1876, it was called Kingsville and later renamed after Thetford, Norfolk, Eng. Situated 60 miles (100 km) south of the city of Quebec, Thetford-Mines ...
Thetis: in Greek mythology, a Nereid loved by Zeus and Poseidon. When Themis (goddess of Justice), however, revealed that Thetis was destined to bear a son who would be mightier than his father, the two gods gave her to Peleus, king ...
Theudis: the first Visigothic king of Spain (531-548), in the sense that he was the first to reside there permanently. An Ostrogoth, he had acquired great possessions in the valley of the Ebro by marriage with a Roman lady when Theodoric ...
thiamin: water-soluble organic compound that is necessary for carbohydrate metabolism in both plants and animals. It carries out these functions in its active form, as a component of the coenzyme thiamin pyrophosphate. Thiamin deficiency results in beriberi, a disease characterized by ...
thiazine: any of three organic compounds of the heterocyclic series, having molecular structures that include a ring of four atoms of carbon and one each of nitrogen and sulfur.
thiazole: any of a class of organic compounds of the heterocyclic series characterized by a ring structure composed of three carbon atoms, one nitrogen atom, and one sulfur atom. This ring structure occurs in such important biologically active natural products as ...
Thibaud, Jacques: French violinist known for his performances of Mozart, Beethoven, and 19th-century French works.
Thibaut, Anton Friedrich Justus: German jurist and leader of the philosophical school that maintained the tradition of natural law in a spirit of moderate rationalism. He is remembered chiefly because his call for the codification of German law, reflecting the rise of German nationalism ...
Thibaw: last king of Burma, whose short reign (1878-85) ended with the occupation of Upper Burma by the British.
Thibodaux: city, seat (1808) of Lafourche parish, southeastern Louisiana, U.S., on Bayou Lafourche, 49 miles (79 km) southwest of New Orleans. The area was occupied by the Colapissa Indians in the 1680s. It was founded as a river depot about 1750 ...
thick-headed fly: an elongated, wasplike insect of the family Conopidae (order Diptera). It is brownish in colour, often with yellow markings, and between about 6 and 25 millimetres (0.2 and 1 inch) long; the head is thicker than the thorax.
thickhead: any of about 35 species constituting the songbird family Pachycephalidae (order Passeriformes), considered by some authors to be a subfamily of Muscicapidae. Thickheads have heavy-looking, seemingly neckless foreparts and are named alternatively for their loud, melodious voices. Thickheads are insectivorous ...
thickknee: any of numerous shorebirds that constitute the family Burhinidae (order Charadriiformes). The bird is named for the thickened intertarsal joint of its long, yellowish or greenish legs; or, alternatively, for its size (about that of a curlew, 35 to 50 ...
Thierry: count of Flanders (1128-68), son of Thierry II, duke of Upper Lorraine, and Gertrude, daughter of Robert I the Frisian, count of Flanders. He contested the county of Flanders with William Clito on the death of Charles the Good in ...
Thierry De Chartres: French theologian, teacher, encyclopaedist, one of the foremost thinkers of the 12th century.
Thierry, Augustin: French historian whose discursive method of presenting history in picturesque and dramatic terms makes him one of the outstanding Romantic historians.
Thiers, Adolphe: French statesman, journalist, and historian, a founder and the first president (1871-73) of the Third Republic. His historical works include a 10-volume Histoire de la revolution francaise and a 20-volume Histoire du consulat et de l'empire.
Thies: city, west-central Senegal. Situated 35 miles (56 km) east of Dakar, it is an important transportation centre, serving as the junction of the eastern Dakar-Niger River railway and the northern rail and road systems. This central location has spawned light ...