Terminology

Leonardo, Vol. 9, pp. 240. Pergamon Press 1976. Printed in Great Britain TERMINOLOGY The terms defined below were selected from artists’ Articles and Notes published in the previous issue of Leonardo. Each definition is followed by an indication of the volume and page number of Leonurdo on which the term first appears. The terms were not found in the art dictionaries among the dictionaries listed in Leonardo 9, 67 (1976) or they are used in a new sense. Some are terms that have been carried over into the field of art from the natural and social sciences, from mathematics and from technology. Numbers in brackets, e.g. [ll, 171, refer to the dictionaries mentioned above. The definitions are not presumed to be unassailable. The Editors would, therefore, welcome the comments of readers on the definitions presented. 746. Carbondioxide, carbonic acid gas (in chemistry)A colorless gas that occurs in the Earth’s atmosphere. It is formed in the combustion of carbonaceous fuels such as wood, coal, fuel oil, propane and natural gas. Animals expel it in respiration and plants absorb it from air to form carbohydrates. It is used in the carbonation of beverages and, being nonflammable and heavier than air, it is used in fighting fires. (9, 89; [14, 171) (cf. Dry ice, Terminology, Leonardo 8,337 (1975), naturalgas, term 753, and propane, term 755.) 747. Carbon monoxide (in chemistry)-A colorless, odorless, very toxic, flammable gas formed along with carbon dioxide in the combustion of carbonaceous fuels such as wood, coal, fuel oil, propane and natural gas when the oxygen available is insufficient for the complete combustion of the fuel. It occurs, for example. in the exhaust fumes from automobile engines. (9, 89; [14]) (cf. Natural gas, term 753, and propane, term 755.) 748. Corona (in astronomy)-The tenuous outermost part of the atmosphere of the Sun. It is seen as a halo around the Moon’s black disc during a total eclipse of the Sun. (9, 95; [3]) nential, Terminology, Leonardo 4, 81 (1971).) 749. Exponent (in muthematics)-(9, 101) (cf. Expo750 . Irrational number (in mathematics)-A number that cannot be expressed as an integer or the quotient of integers, as 2/2 and T. (9, 130; [3]) 751. Magnesia, magnesium oxide (in chemistry)-A white powdery substance used in the manufacture of refractories, cements, thermal insulation products, glass, etc. (9, 90; [3, 171) 752. Metronome-A pendulum-type device designed to mark time intervals by a regularly repeated tick. It is especially used in music. (9, 130; [17]) 753. Natural gas (in chemistry-A gas issuing from the Earth’s crust through natural openings or bored wells. It is a combustible mixture of gaseous substances that is used commonly as a fuel and as a raw material in chemicals manufacture. (9, 92; 1171) 754. Pentagon (in geometry)-A closed plane figure bounded by five straight lines. A pentagon whose sides and interior angles are all equal is called a regular pentagon. (9, 130; [13, 171) 755. Propane (in chemistry)-One of a series of gaseous substances found in crude petroleum and in natural gas. It is separated for use as a special kind of fuel and as a raw material in chemicals manufacture. As a fuel it is available as a liquid under pressure in steel vessels. In this form it is known as LPG (liquified petroleum gas). (9, 92; [I711(cf. Nururalgas, term 753) 756. Science fiction machines (in visual art)-A term coined by Charles Alexander for objects that are intended as visual jokes. Some of them are of a kinetic-art type. (9, 119) 757. Vector (inphysics)-A line representing a physical quantity that has magnitude and direction in space, as velocity, acceleration or force. (9, 100; (31) 240 ...