Encyclopædia Britannica Australia -

Encyclopedias since 1768

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hetaera ... hiatus

hetaera: (Female Companion), one of a class of professional independent courtesans of ancient Greece who, besides developing physical beauty, cultivated their minds and talents to a degree far beyond that allowed to the average Attic woman. Usually living fashionably alone, or ...
heterochlorid: any protozoan of the plantlike flagellate order Heterochlorida. Heterochlorids have two flagella of unequal length and chromatophores whose pigments vary from yellow to yellow-green. Food reserves are stored as leucosin (probably a carbohydrate) and lipids. Some genera may be amoeboid ...
heterocyclic compound: any of a class of organic chemical substances that consist of molecules containing one or more rings of atoms with at least one atom being an element other than carbon. The class includes many compounds of biological importance, such as ...
heterogeneous reaction: any of a class of chemical reactions in which the reactants are components of two or more phases (solid and gas, solid and liquid, two immiscible liquids) or in which one or more reactants undergo chemical change at an interface, ...
heterophony: in music, texture resulting from simultaneous performances of melodic variants of the same tune, typical of Middle Eastern practices as well as of a vast array of folk music. Balkan Slavic epic singers, for example, accompany themselves heterophonically on the ...
heteropteran: any member of the insect order Heteroptera, which comprises the so-called true bugs. (Some authorities use the name Hemiptera; others consider both the heteropterans and the homopterans to be suborders of the Hemiptera.) This large group of insects, consisting of ...
heterosis: the increase in such characteristics as size, growth rate, fertility, and yield of a hybrid organism over those of its parents. Plant and animal breeders exploit heterosis by mating two different pure-bred lines that have certain desirable traits. The first-generation ...
heterospecific mating: mating in which the man and woman have incompatible blood types, such that the woman may develop antibodies to her partner's blood type. This mating causes difficulties in childbirth, since there is a chance that the child conceived in a ...
heterotrich: any member of the ciliated protozoan order Heterotrichida. Complete ciliation is typical, although there is a tendency toward loss of the cilia, which are minute, hairlike processes, in several families (Peritromidae, Licnophoridae). Heterotrichs are considered the most primitive of the ...
hetman: military title used in the Polish-Lithuanian state (16th-18th century); the hetman wielki ("great hetman") was the chief of the armed forces and the commander in the field when the king was not present. In Ukraine a variation of the term, ...
Hettangian Stage: the lowest of 11 stages in the Jurassic System, consisting of rocks deposited globally during the Hettangian Age (208 to 204 million years ago). It directly underlies the Sinemurian Stage. Nominally, the base of the Hettangian Stage defines the upper ...
Hettner, Alfred: German geographer who sought to place geography on a firm philosophical and scientific foundation. He strongly influenced the modern development of geography in Germany.
heulandite: hydrated sodium and calcium aluminosilicate mineral in the zeolite family, formulated (Ca,Na₂)Al₂Si₇O₁₈·6H₂O. It forms brittle, transparent, coffin-shaped crystals in various shades of white through red, gray, or brown. Heulandite's molecular structure is an open framework containing six-membered rings of silicate ...
Heuneburg: Celtic fortified site overlooking the Danube River in Baden-Wurttemberg Land (state), Germany. Recent excavations have shown that the Heuneburg fort community carried on a prosperous trade with the Greeks at Massilia (Marseille) during the 6th century BC. Imported Greek black-figure ...
Heureaux, Ulises: president of the Dominican Republic who allowed most of his country's economy to fall under U.S. control. The republic's fiscal disorder led to American intervention after Heureaux's assassination.
Heusler alloy: any of the first magnetic alloys composed of metals that, in their pure state, are not magnetic. The alloys are named after Fritz Heusler, 19th-century German mining engineer and chemist. Heusler alloys consist of approximately two parts of copper, one ...
Heuss, Theodor: liberal democratic legislator, first president of West Germany, author, and leader of the Free Democratic Party (Freie Demokratische Partei, FDP). He also helped draft a new constitution for postwar West Germany.
Heutsz, Johannes Benedictus van: Dutch general and governor-general of the Dutch East Indies (1904-09) who conquered the Sumatran kingdom of Acheh (Atjeh) and brought all of Indonesia directly under Dutch rule.
Hevajra: in northern Buddhism, a fierce protective deity, the yab-yum (in union with his female consort, Vajrayogini) form of the fierce protective deity Heruka. Hevajra is a popular deity in Tibet, where he belongs to the yi-dam (tutelary, or guardian, deity) ...
Hevelius, Johannes: astronomer who compiled an atlas of the Moon (Selenographia, published 1647) containing one of the earliest detailed maps of its surface as well as names for many of its features. A few of his names for lunar mountains (e.g., the ...
Heves: megye (county), northern Hungary. From the Tisza River in the southeast, the county extends northward into the Matra and Bukk mountains (qq.v.), which are popular year-round resort areas with facilities for winter sports and hunting. Sanatoriums are also located there. ...
Hevesy, Georg Charles von: chemist and recipient of the 1943 Nobel Prize for Chemistry. His development of isotopic tracer techniques greatly advanced understanding of the chemical nature of life processes. In 1923 he also discovered, with the Dutch physicist Dirk Coster, the element hafnium.
Hewart, Gordon Hewart, 1st Viscount: lord chief justice of England from 1922 to 1940.
Hewish, Antony: British astrophysicist who won the Nobel Prize for Physics in 1974 for his discovery of pulsars (cosmic objects that emit extremely regular pulses of radio waves).
Hewitt, Abram Stevens: American industrialist, philanthropist, and politician who in 1886 defeated Henry George and Theodore Roosevelt to become mayor of New York City.
Hewitt, Peter Cooper: American electrical engineer who invented the mercury-vapour lamp, a great advance in electrical lighting.
Hewlett-Packard Company: American manufacturer of computers, computer peripherals, and instrumentation equipment with headquarters in Palo Alto, California.
Hewson, William: British anatomist and physiologist who described blood coagulation and isolated a key protein in the coagulation process, fibrinogen, which he called coagulable lymph. He also investigated the structure of the lymphatic system and described red blood cells.
hex sign: emblem painted on a barn, especially in Pennsylvania Dutch country, an agricultural region in southeastern Pennsylvania largely settled by German immigrants who have preserved ethnic custom and identification to a high degree (see Pennsylvania German). Hex designs, usually round, with ...
hexachloroplatinic acid: complex compound formed by dissolving platinum metal in aqua regia (a mixture of nitric and hydrochloric acids) or in hydrochloric acid that contains chlorine. It is crystallized from the solution in the form of reddish brown deliquescent (moisture-absorbing) crystals with ...
hexachord: in music, six-note pattern corresponding to the first six tones of the major scale (as, C-D-E-F-G-A). The names of the degrees of the hexachord are ut, re, mi, fa, sol, and la (also called solmization [q.v.] syllables); they were devised ...
hexagonal system: one of the principal categories of structures to which a given crystalline solid can be assigned. Components of crystals in this system are located by reference to four axes-three of equal lengths set at 120° to one another and a ...
hexahedrite: any iron meteorite containing about 6 percent nickel and having a cubic cleavage and crystal structure. Etching the polished surface of a hexahedrite often brings out a design called Neumann lines, usually caused by the presence of systems of very ...
hexameter: a line of verse containing six feet, usually dactyls (' ˘ ˘). Dactylic hexameter is the oldest known form of Greek poetry and is the preeminent metre of narrative and didactic poetry in Greek and Latin, in which its position ...
Hexapla: (Greek: "Sixfold"), edition of the Old Testament compiled by Origen of Alexandria in Caesarea, Palestine, before AD 245. The Hexapla presented for comparison the Hebrew text of the Old Testament, the Hebrew text in Greek characters, and the Greek versions ...
Hexham: town, Tynedale district, administrative and historic county of Northumberland, England, on the upper River Tyne. Its abbey church of St. Andrew, containing a great stone staircase, dominates the town. The church and monastery were founded about 673 by the archbishop ...
Heyden, Jan van der: leading painter of cityscapes in late-17th-century Holland, especially known for his views of Amsterdam done in the 1660s.
Heydrich, Reinhard: Nazi German official who was Heinrich Himmler's chief lieutenant in the Schutzstaffel ("Protective Echelon"), the paramilitary corps commonly known as the SS. He played a key role in organizing the Holocaust during the opening years of World War II.
Heyerdahl, Thor: Norwegian ethnologist and adventurer who organized and led the famous Kon-Tiki (1947) and Ra (1969-70) transoceanic scientific expeditions. Both expeditions were intended to prove the possibility of ancient transoceanic contacts between distant civilizations and ...
Heymans, Corneille: Belgian physiologist who received the Nobel Prize for Physiology or Medicine in 1938 for his discovery of the regulatory effect on respiration of sensory organs associated with the carotid artery in the neck and with the aortic arch leading from ...
Heyn, Piet: admiral and director of the Dutch West India Company who captured a Spanish treasure fleet (1628) with 4,000,000 ducats of gold and silver (12,000,000 gulden, or florins). That great naval and economic victory provided the Dutch Republic with money to ...
Heyrovsky, Jaroslav: Czech chemist who received the Nobel Prize for Chemistry in 1959 for his discovery and development of polarography.
Heyse, Paul Johann Ludwig von: German writer and prominent member of the traditionalist Munich school who received the Nobel Prize for Literature in 1910.
Heyward, DuBose: American novelist, dramatist, and poet whose first novel, Porgy (1925), was the basis for a highly successful play, an opera, and a motion picture.
Heywood, Jasper: Jesuit priest and poet whose translations of the works of the Roman playwright Seneca, including Troades (1559), Thyestes (1560), Hercules furens (1561), and other plays issued as Seneca His Tenne Tragedies Translated into English (1581), influenced English drama. A son ...
Heywood, John: playwright whose short dramatic interludes helped put English drama on the road to the fully developed stage comedy of the Elizabethans. He replaced biblical allegory and the instruction of the morality play with a comedy of contemporary personal types that ...
Heywood, Thomas: English actor-playwright whose career spans the peak periods of Elizabethan and Jacobean drama.
Hezbollah: militia group and political party that first emerged as a faction in Lebanon following the Israeli invasion of that country in 1982.
Hezekiah: son of Ahaz, and the 13th successor of David as king of Judah at Jerusalem. The dates of his reign are often given as about 715 to about 686 BC, but inconsistencies in biblical and Assyrian cuneiform records have yielded ...
Hialeah: city, Miami-Dade county, southeastern Florida, U.S. It lies on the Miami Canal, just northwest of Miami. The area was originally inhabited by Tequesta and later by Seminole Indians. Settled in 1921 by aviation pioneer Glenn Curtiss and Missouri cattleman James ...
hiatus: in prosody, a break in sound between two vowels that occur together without an intervening consonant, both vowels being clearly enunciated. The two vowels may be either within one word, as in the words Vienna and naive, or the final ...