Prandtl \'pran-t 3 l\, Ludwig (b. Feb. 4, 1875, Freising, Ger.—d. Aug. 15, 1953, Gottingen, W.Ger.) German physicist, considered the father of aerodynamics. He taught at the University of Gottingen (1904-53). His 1904 discovery of the boundary layer at the surface of a body moving in air or water led to an understanding of skin friction drag and of the way streamlining (see streamline) reduces the drag of airplane wings and other moving bodies. His work on wing theory explained the process of airflow over airplane wings.
prasada Vpro-'sa-dsV In Hinduism, consecrated food offered to the deity and then distributed to worshipers, who consume it as a sign of the god’s favour. Prasada is used both in temple ceremonies, where it may be offered to a god such as Krishna and then distributed by the priests, and at household shrines, where it is offered to the god and then handed out to household members. See also puja.
pratitya-samutpada Xpro-'tet-yo-.ss-mut-'pa-doV In Buddhism, the chain of causation that leads from rebirth to death. Existence is seen as an interrelated flux of transient events that occur in a series, one produc¬ ing another, usually described as a chain of 12 links: (1) ignorance, which leads to (2) faulty perceptions of reality, which provide the structure of (3) knowledge, which addresses (4) name and form, or the principle of individual identity and the sensory perception of an object, experienced through (5) the six domains (the five senses and their object, along with the mind), whose presence leads to (6) contact (between objects and the senses), followed by (7) sensation, which, being pleasant, leads to (8) thirst and then (9) grasping (as of sex partners), which leads to (10) the process of becoming, culminating in (11) birth, and at last (12) old age and death.
Pratt, E(dwin) J(ohn) (b. Feb. 4, 1883, Western Bay, Nfd., Can.—d. April 26, 1964, Toronto, Ont.) Canadian poet. He trained for the ministry
and later taught for many years at the University of Toronto. The early col¬ lection The Titans { 1926) contains his widely read “The Cachalot,” an account of a whale hunt. Brebeufand His Brethren (1940), perhaps his best work, chronicles the martyrdom of Jesuit missionaries. Later collections include Dunkirk (1941), They Are Returning (1945), Behind the Log (1947), and Towards the Last Spike
(1952).
Pratt, Francis Ashbury (b. Feb. 15, 1827, Woodstock, Vt., U.S.—d. Feb. 10, 1902, Hartford, Conn.) U.S. inventor. With Amos Whitney he founded the Pratt & Whitney Co. in Hartford to manufacture machine tools. He was instrumental in bring¬ ing about adoption of a standard sys¬ tem of gauges. He also invented a metal-planing machine (1869), a gear cutter (1884), and a milling machine (1885).
Prajnaparamita, 13th-century stone sculpture from Singosari, East Java; in the Museum Pusat, Jakarta, Indonesia
© 2006 Encyclopaedia Britannica, Inc.
Pratt Institute ► precession I 1541
Pratt Institute Private institution of higher learning in Brooklyn, New York, New York, U.S. It was founded as a trade school in 1887 by the industrialist Charles Pratt (1830-91). It comprises schools of architecture, art and design (for which it is especially renowned), liberal arts and sci¬ ences, professional studies, and information and library science. It has both bachelor’s and master’s degree programs.
pratyaya \pr9t-'ya-y9\ In Buddhism, an auxiliary, indirect cause, as dis¬ tinguished from a direct cause ( hetu ). A seed, for example, is the direct cause of a plant, whereas sunlight, water, and earth are the auxiliary causes. Sometimes pratyaya is used to refer to cause in general. The idea of causation is important in the Buddhist concept of the cycle of death and rebirth (see pratitya-samutpada).
pratyeka-buddha \prot-'ya-k9\ In Buddhism, one who attains enlight¬ enment through his own efforts rather than by listening to the teachings of a buddha. The way of the self-enlightened buddha was retained only in the Theravada tradition. Mahayana Buddhism rejects the path of self¬ enlightenment as too limiting and embraces the ideal of the bodhisattva, who postpones final enlightenment to work for the salvation of others.
Pravda \'prav-da\ Russian "Truth" Former daily newspaper published in Moscow and distributed nationwide, the official organ of the Commu¬ nist Party of the Soviet Union (1918-91). It was founded in St. Peters¬ burg as an underground paper by Vladimir Ilich Lenin and two colleagues in 1912. As a Soviet state newspaper and central source of information and education, it offered well-written articles and analyses on science, economics, cultural topics, and literature as well as materials to indoctri¬ nate and inform readers on communist theory and programs. Topics con¬ cerning international relations were largely left to the government paper Izvestiya. After communist power ended in 1991, most of its readership evaporated; it became the voice of the conservative-nationalist opposition and ceased publication in 1996.
Praxiteles \prak-'si-t 3 l-,ez\ (fl. c. 370-330 bc, Greece) Greek sculptor. His only known surviving work, the marble Hermes Carrying the Infant Dionysus, displays delicate modeling and exquisite surface finish. A few other works survive in Roman copies. His most celebrated work was the Aphrodite of Cnidus, which Pliny the Elder considered the best statue in the world. Through Praxiteles’ influence, figures were increasingly shown standing in graceful, sinuous poses, leaning lightly on some support, a pose further developed by sculptors of the Hellenistic Age. Greatest and most original of the 4th-century Attic sculptors, he profoundly influenced the later course of Greek sculpture.
Prayag Raj See Allahabad
prayer Silent or spoken petition made to God or a god. Prayer has been practiced in all religions throughout history. Its characteristic postures (bowing the head, kneeling, prostration) and position of the hands (raised, outstretched, clasped) signify an attitude of submission and devotion. Prayer may involve con¬ fessions of sin, requests, thanks, praise, offerings of sacrifice, or prom¬ ises of future acts of devotion. In addition to spontaneous private prayer, most religions have fixed for¬ mulas of prayer (e.g., the Lord's Prayer), often recited in group wor¬ ship. The four prophetic religions (Judaism, Christianity, Islam, and Zoroastrianism) prescribe a daily set form of individual prayer, such as the Shema, to be recited twice a day by every male Jew, and the Islamic salat, performed five times a day.
prayer wheel In Tibetan Buddhism, a mechanical device used as an equivalent to the recitation of a man¬ tra. The prayer wheel consists of a
hollow metal cylinder, often beautifully embossed, mounted on a rod and containing a consecrated paper bearing a mantra. Each turn of the wheel by hand is considered equivalent to orally reciting the prayer. Variants to the handheld prayer wheel are large cylinders that can be set in motion by hand or attached to windmills or waterwheels and thus kept in con¬ tinuous motion.
praying mantis See mantis
Pre-Raphaelites X.pre-'ra-fe-a-JItsN Group of young British painters, led by Dante Gabriel Rossetti, William Holman Hunt, and John Everett Mill¬ ais, who banded together in 1848 in reaction against what they considered the unimaginative and artificial historical painting of the 18th and early 19th centuries, seeking to express a new moral seriousness and sincerity in their works. Their name, the Pre-Raphaelite Brotherhood, honoured the simple depiction of nature in Italian art before Raphael; the symbolism, imagery, and mannered style of their paintings often suggest a faux- medieval world. Later members included Edward Burne-Jones and George Frederic Watts (1817-1904). The group also functioned as a school of writers who often used medieval settings, sometimes with shocking effect, as in William Morris’s The Defence ofGuenevere (1858), which deals with issues of love and sex. Though active less than 10 years, the group had a profound influence on the arts.