Aeneas \i-'ne-3s\ Mythical hero of Troy and Rome. He was the son of Aphrodite and Anchises, a member of Trojan royal family. According to Homer, he was second only to his cousin Hector in defending Troy dur¬ ing the Trojan War. Virgil’s Aeneid tells of Aeneas’s escape after Troy’s fall, carrying his elderly father on his back, and of his journey to Italy, where his descendants became the rulers of Rome. See also Dido.
Aeolian harp \e-'o-le-9n\ Stringed instrument played by the wind (named for the wind god Aeolus). It is usually a long, narrow, shallow box with soundholes and 10 or 12 strings strung lengthwise between two bridges. The strings are of the same length but different thicknesses and are all tuned to the same pitch; the wind makes them vibrate in succes¬ sively higher harmonics. The harp may be hung, or set horizontally under a window sash. The first known Aeolian harp was constructed c. 1650 by Athanasius Kircher (1601-1680).
Aeolus Ye-a-lssV Greek god of the winds. In the Odyssey Homer repre¬ sents Aeolus as the mortal ruler of the floating island of Aeolia. He gives Odysseus a favourable wind for his voyage and a bag in which the unfavourable winds are confined, but Odysseus’s careless companions open the bag, releasing the winds and driving their ship back to shore. Later writers depicted Aeolus as a minor god rather than a human being. The Aeolian harp is named for him.
aeon or eon \'e-,an\ In Gnosticism or Manichaeism, one of the orders of spirits, or spheres of being, emanating from the godhead. The first aeon emanated directly from unmanifested divinity and was charged with divine force. Aeons increased in number and decreased in divine energy with increased remoteness from the divinity. At sufficient remoteness, error became possible and was the source of the material universe. Aeons may be viewed positively, as embodiments of the divine, or negatively, as media through which the soul must pass to reach its divine origin.
aepyornis \,e-pe-'6r-n3s\ or elephant bird Any of a group of giant flightless birds in the extinct genus Aepyornis, found as fossils in Pleis-
The temple of Aphaea, Aegina, Greece
SUSAN MCCARTNEY-PHOTO RESEARCHERS
Aegirine crystals from Magnet Cove, Arkansas
BY COURTESY OF THE FIELD MUSEUM OF NATURAL HISTORY, CHICAGO; PHOTOGRAPH, JOHN H. GERARD
© 2006 Encyclopaedia Britannica, Inc.
aerarium ► aesthetics I 21
tocene and post-Pleistocene deposits on Madagascar. Most were massively constructed (some stood more than 10 ft, or 3 m, high) and had a small skull and a long slim neck. Remains of aepyomis and its eggs (as large as 3 ft, or 1 m, in circumference) are common. Its ancestry is uncertain.
aerarium (Saturni) Central treasury of ancient Rome, housed in the Temple of Saturn. During the republic (509-27 bc), two quaestors man¬ aged the treasury and the Senate controlled it. All revenues were paid into the aerarium, and approved payments were made from it. Under the prin- cipate (27 bc-ad 305) the aerarium lost funds and importance as emper¬ ors and magistrates bypassed Senate control and drew directly from the fisci (provincial treasuries). From ad 6 Augustus used taxes to fund the aerarium militare, a public treasury, to reward veterans, and the aerar¬ ium Saturni became the treasury of the city of Rome.
aerial See antenna
aerial perspective Method of producing a sense of depth in a paint¬ ing by imitating the effect of atmosphere that makes objects look paler, bluer, and hazier or less distinct in the middle and far distance. The term was coined by Leonardo da Vinci, but the technique can be seen in ancient Greco-Roman wall paintings (e.g., at Pompeii). It was discovered that dust and moisture in the atmosphere caused the scattering of light passing through it; short-wavelength light (blue) is scattered most and long- wavelength light (red) least. Italian painters in Leonardo’s time used the device; it was exploited by 15th-century northern European artists and later by J.M.W. Turner.
aerobatics Sport of performing maneuvers such as rolls, loops, stalls, spins, and dives with an airplane. As an organized sport, rather than as an air show attraction (“stunt flying”), aerobatics began international com¬ petition in 1960 under the auspices of the Federation Aeronautique Inter¬ nationale.
aerobics System of physical conditioning for increasing the efficiency of the body’s intake of oxygen. Aerobic exercises (e.g., running, jogging, swimming, dancing) stimulate heart and lung activity. To produce a ben¬ efit, aerobic training must raise the heart rate (pulse) to the exerciser’s target level for at least 20 minutes and include at least three sessions a week. The concept of aerobics was pioneered by Kenneth H. Cooper and popularized in his books Aerobics (1968) and The Aerobics Way (1977).
aerodynamics Branch of physics concerned with the forces acting on bodies passing through air and other gaseous fluids. It explains the prin¬ ciples of flight of aircraft, rockets, and missiles. It is also involved in the design of automobiles, trains, and ships, and even stationary structures such as bridges and tall buildings, which must withstand high winds. Aerodynamics emerged as a discipline around the time of Wilbur and Orville Wright’s first powered flight in 1903. Developments in the field have led to major advances in turbulence theory and supersonic flight.
Aeroflot \,ar-9-'fl6t\ -Russian Airlines National airline of the former Soviet Union. Founded in 1928 as Dobroflot, it was reorganized as Aer¬ oflot in 1932. During the Soviet era Aeroflot was the world’s largest air¬ line, with about 15% of all civil air traffic. After the 1991 breakup of the Soviet Union, Aeroflot surrendered its monopoly over commercial air travel in the former Soviet states. It was renamed Aeroflot-Russian Air¬ lines in June 2000.
aerosol System of tiny liquid or solid particles evenly distributed in a finely divided state through a gas, usually air. Aerosol particles partici¬ pate in chemical processes and influence the electrical properties of the atmosphere. Though true aerosol particles range in diameter from a few nanometres to about one micrometre, the term is commonly used to refer to fog or cloud droplets and dust particles, which can have diameters of more than 100 micrometres. See also colloid; emulsion.
aerospace engineering Field concerned with the development, design, construction, testing, and operation of airplanes and spacecraft. The field has its roots in balloon flight, gliders, and airships, and in the 1960s it was broadened to include space vehicles. Principal technologies are those of aerodynamics, propulsion, structure and stability, and control. Aerospace engineers in academic, industrial, and government research centres cooperate in designing new products. Flight testing of prototypes follows, and finally quantity production and operation take place. Impor¬ tant developments in aerospace engineering include the metal monocoque fuselage, the cantilevered monoplane wing, the jet engine, supersonic flight, and spaceflight.
aerospace medicine Branch of medicine, pioneered by Paul Bert, dealing with atmospheric flight (aviation medicine) and space flight (space medicine). Intensive preflight simulator training and attention to design of equipment and spacecraft promote the safety and effectiveness of humans exposed to the stresses of flight and can prevent some problems. The world’s first unit for space research was established in the U.S. in 1948. Physicians trained in aerospace medicine are known as flight sur¬ geons.
Aeschines Ves-ko-.nezX (b. 390 bc —d. c. 314 bc) Athenian orator. He and Demosthenes, who later became his bitter opponent, participated in 346 bc in forging a peace between Athens and Macedonia. Demosthenes later accused Aeschines of treason because he had promoted the Mace¬ donian cause during the negotiations. At a trial (343) Aeschines was acquitted by a narrow majority. In 339 he helped incite the war that led to the Battle of Chaeronea and to Macedonian control of central Greece. In 336 he opposed as illegal a motion to honour Demosthenes; the mat¬ ter came to trial in 330, and Aeschines suffered an overwhelming defeat.