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lubrication

(Encyclopedia)lubrication, introduction of a substance between the contact surfaces of moving parts to reduce friction and to dissipate heat. A lubricant may be oil, grease, graphite, or any substance—gas, liquid...

Fellenberg, Philipp Emanuel von

(Encyclopedia)Fellenberg, Philipp Emanuel von fēˈlĭp āmäˈno͞oĕl fən fĕlˈənbĕrkh [key], 1771–1844, Swiss educator and agriculturist. He purchased (1799) an estate, Hofwyl (near Bern), where he put int...

Ibn Tufayl

(Encyclopedia)Ibn Tufayl ĭˈbən to͞ofālˈ [key], d. 1185/86?, 12th-century Spanish-Arab philosopher and physician, b. near Granada. His chief work was a philosophical romance, Hayy ibn Yaqzan, describing the de...

initiation

(Encyclopedia)initiation, the transition and attendant ceremonies, such as ordeals and rites, involved in passing from one state or status to another, often from childhood to adulthood. It was among the most import...

Reed, Walter

(Encyclopedia)Reed, Walter, 1851–1902, American army surgeon, b. Gloucester co., Va. In 1900 he was sent to Havana as head of an army commission to investigate an outbreak of yellow fever among American soldiers....

Frederick III, elector of Saxony

(Encyclopedia)Frederick III or Frederick the Wise, 1463–1525, elector of Saxony (1486–1525). At Wittenberg he founded (1502) the university where Martin Luther and Melanchthon taught. At a crucial period for th...

aureole, in physics

(Encyclopedia)aureole ôrˈēōlˌ [key], in physics, luminous circle seen when the sun or other bright light is observed through a diffuse medium, i.e., smoke, thin cloud, fog, haze, or mist. It sometimes occurs a...

Tasaday

(Encyclopedia)Tasaday, alleged band of 25 hunter-gatherers living in the Philippine rain forest, purportedly contacted by Westerners for the first time in 1971 in southern Mindanao (Cotabato Province). They reporte...

sociolinguistics

(Encyclopedia)sociolinguistics, the study of language as it affects and is affected by social relations. Sociolinguistics encompasses a broad range of concerns, including bilingualism, pidgin and creole languages, ...

ultrasonics

(Encyclopedia)ultrasonics, study and application of the energy of sound waves vibrating at frequencies greater than 20,000 cycles per second, i.e., beyond the range of human hearing. The application of sound energy...