zipper Device for binding the edges of an opening, as on a garment or a bag. A zipper consists of two strips of material with metal or plastic teeth along the edges, and a sliding piece that interlocks the teeth when moved in one direction and separates them again when moved in the opposite direc¬ tion. The idea of a slide fastener was first exhibited by Whitcomb L. Judson (died 1909) at the World’s Columbian Exposition of 1893. The modern form of the zipper began to appear on clothing in the late 1920s.
zircon Silicate mineral, zirconium silicate, ZrSi0 4 , the principal source of zirconium. Zircon is widespread as an accessory mineral in acid igneous rocks; it also occurs in metamorphic rocks and, fairly often, in detrital deposits. It occurs in beach sands in many parts of the world, particularly Australia, India, Brazil, and Florida, and is a common heavy mineral in sedimentary rocks. Gem varieties occur in stream gravels and detrital deposits, particularly in Indochina and Sri Lanka, but also in Myanmar,
Australia, and New Zealand. Zircon forms an important part of the syenite of southern Norway and occurs in large crystals in Quebec.
zirconium Metallic chemical ele¬ ment, one of the transition elements, chemical symbol Zr, atomic number 40. The metal is hard and brittle when impure, soft and ductile when highly purified. It is relatively abundant, occurring as zircon (also marketed as a natural gemstone) and baddeleyite. Highly transparent to neutrons, zirconium became important in the 1940s in nuclear energy applications such as fuel cladding. Other uses are in alloys, fireworks, and flashbulbs and as a scavenger for oxygen and other gases. Its compounds, in most of which it has valence 4, are important industrial materials. Zirconia (the oxide) is used in piezoelectric crystals (see piezoelectricity), high-frequency induction coils, coloured glazes and glasses, and heat-resistant fibres; zirconium carbonate is employed in preparations to treat the rash of poison ivy.
zither Plucked or struck stringed instrument with a shallow soundbox. The common Austrian zither is roughly rectangular and has 30-40 strings;
Zircon with quartz from Cheyenne Canyon, Colorado
COURTESY OF THE FIELD MUSEUM OF NATURAL HISTORY, CHICAGO; PHOTOGRAPH, JOHN H. GERARD-EB INC.
it is placed on the player’s knees or on a table. Several melody strings pass over a fretted fingerboard; the player’s left hand stops these strings, while the right hand plucks with the fingers and a thumb plectrum. Zither is also a generic term for stringed instruments, the strings of which are fastened across a frame that lacks any projecting neck or arms. The larger zither family thus includes instruments such as the Aeolian harp, autoharp, cimbalom, dulcimer, koto, and even the clavichord, harpsichord, and piano.
Zoan See Tanis
zodiac \'zo-de-,ak\ Belt around the heavens extending about 9° on either side of the ecliptic. The orbits of the Moon and the major planets (except Pluto) lie entirely within the zodiac. In astrology, each of 12 constella¬ tions along this circle is considered to occupy 1/12 (30°) of it. The posi¬ tions of the Sun and planets when a person is born and their motion through these constellations are said to exert influence on his or her life, though precession of the equinoxes has shifted the constellations eastward and the Sun no longer passes through them on the traditional dates: Aries, the ram (March 21-April 19); Taurus, the bull (April 20-May 20); Gemini, the twins (May 21-June 21); Cancer, the crab (June 22-July 22); Leo, the lion (July 23-August 22); Virgo, the virgin (August 23-September 22); Libra, the balance (September 23-October 23); Scorpius (see Scorpio), the scorpion (October 24-November 21); Sagittarius, the archer (November 22-December 21); Capricornus (see Capricorn), the goat (December 22-January 19); Aquarius, the water bearer (January 20-February 18); Pisces, the fish (February 19-March 20).
Zither made in Vienna
COURTESY OF A.V. EBBLEWHITE, LONDON; PHOTOGRAPH, BEHR PHOTOGRAPHY/EB INC.
The astrological images and symbols of the zodiac.
© MERRIAM-WEBSTER INC.
zodiacal light \zo-'dI-9-k9l\ Band of very faint light in the night sky. It is thought to be sunlight reflected from interplanetary dust grains lying mostly in the plane of the zodiac, or ecliptic. Seen in the west after twi¬ light and in the east before dawn, it is most clearly visible in the tropics, where the ecliptic is approximately perpendicular to the horizon. In mid- northern latitudes it is best seen evenings in February and March and mornings in September and October (vice versa in midsouthern latitudes). The light can be followed visually to a point about 90° from the Sun. It continues to the region opposite the Sun, where a slight enhancement, the gegenschein, is visible.
© 2006 Encyclopaedia Britannica, Inc.
2112 I Zoe ► Zoroastrianism and Parsiism
Zoe \'zo-e\ (b. c. 978, Constantinople—d. 1050, Constantinople) Byz¬ antine empress. The daughter of Constantine VIII, she married Romanus III Argyrus in 1028. He died in 1034, perhaps poisoned by her, and she married her lover and chamberlain, who became Michael IV. After his death in 1041, his successor, Michael V, banished Zoe to a convent; she was recalled by public outcry, and Michael was deposed, blinded, and exiled (1042). Zoe and her sister became uneasy corulers, and she mar¬ ried Constantine IX Monomachus to secure her throne.
Zog I Albanian Ahmed Bey Zogu (b. Oct. 8, 1895, Castle Burgajet, Alb.—d. April 9, 1961, Suresnes, France) President (1925-28) and king of Albania (1928-39). After serving in the Austrian army in World War I, he became a leader of Albania’s reformist Popular Party. He held ministerial posts in the government (1920-24) and was elected head of the Albanian republic in 1925. Proclaimed king in 1928, he pursued a policy of close collaboration with Italy. Unable to resist Benito Mussolini’s increasing con¬ trol of the country’s finances and army, he was forced into exile when Italy invaded and made Albania a protectorate (1939). After World War II Alba¬ nia became a communist republic, and Zog formally abdicated in 1946.
Zola Vzo-lo,\ French \zo-'la\, Emile (-Edouard-Charles- Antoine) (b. April 2, 1840, Paris, France—d. Sept. 28, 1902, Paris) French novelist and critic. Raised in straitened circumstances, Zola worked at a Paris publishing house for several years during the 1860s while estab¬ lishing himself as a writer. In the gruesome novel Therese Raquin (1867), he put his “scientific” theories of the determination of character by heredity and environment into practice for the first time. These ideas established him as the founder of naturalism in literature. In 1870 he began the ambi¬ tious project for which he is best known, the Rougon-Macquart Cycle (1871-93), a sequence of 20 novels documenting French life through the lives of the violent Rougon family and the passive Macquarts. It includes LAssommoir (1877), a study of alcoholism that is among his most suc¬ cessful and popular novels; Nana (1880); Germinal (1885), his master¬ piece; and La Bete humaine (1890). Among his other works are two shorter novel cycles and treatises explaining his theories on art, including The Experimental Novel (1880). He is also notable for his involvement in the Alfred Dreyfus affair, especially for his open letter, “J’accuse” (1898), denouncing the French army general staff. He died under suspicious cir¬ cumstances, overcome by carbon-monoxide fumes in his sleep.
Zollverein Vtsol-ver-.InN (German: “Customs Union”) Free-trade area throughout much of Germany established in 1834 under Prussian leader¬ ship. The customs union developed from the 1818 Prussian tariff law that abolished internal customs dues and the customs union set up in 1828 in southern Germany by Bavaria and Wiirttemberg. By 1834 other German states had joined, for a total of 18 members; more joined in subsequent years. The Zollverein represented an important step in German unifica¬ tion. See also Friedrich List.