eccentric apparatus
41Drill string — A drill string on a drilling rig is a column, or string, of drill pipe that transmits drilling fluid (via the mud pumps) and torque (via the kelly drive or top drive) to the drill bit. The term is loosely applied as the assembled collection of… …
42Rare Earth hypothesis — In planetary astronomy and astrobiology, the Rare Earth hypothesis argues that the emergence of complex multicellular life (metazoa) on Earth required an improbable combination of astrophysical and geological events and circumstances. The term… …
43Professor Calculus — (Professeur Tournesol) Publication information Publisher Casterman (Belgium) …
44Mitral regurgitation — See also: aortic insufficiency and tricuspid insufficiency Mitral regurgitation Classification and external resources Mitral regurgitation (schematic drawing) During systole, contraction of the left …
45Butterfly valve — A butterfly valve is a type of flow control device, typically used to regulate a fluid flowing through a section of pipe. The valve is similar in operation to a ball valve. A flat circular plate is positioned in the center of the pipe. The plate… …
46Mercury in the fiction of Leigh Brackett — The planet Mercury appears frequently as a setting for many of the stories of Leigh Brackett, and Mercury and Mercurians are frequently mentioned in other stories of the Leigh Brackett Solar System. Brackett s Mercury shares some characteristics… …
47Cremation in the Christian World — Columbarium niches built into the side of St. Joseph s Chapel Mausoleum at the Catholic Mount Olivet Cemetery, Key West (rural Dubuque), Iowa. Today, cremation is an increasingly popular form of disposition of the deceased. This is true even in… …
48ancient Greek civilization — ▪ historical region, Eurasia Introduction the period following Mycenaean civilization, which ended in about 1200 BC, to the death of Alexander the Great, in 323 BC. It was a period of political, philosophical, artistic, and scientific… …
49materials testing — Introduction measurement of the characteristics and behaviour of such substances as metals, ceramics, or plastics under various conditions. The data thus obtained can be used in specifying the suitability of materials for various… …
50motion picture, history of the — Introduction history of the medium from the 19th century to the present. Early years, 1830–1910 Origins The illusion of motion pictures is based on the optical phenomena known as persistence of vision and the phi phenomenon. The first …
