Terminology

Leonardo, Vol. 11, p. 147. Pergamon Press 1978. Printed in Great Britain T E R MINOLOGY 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 Leonardo on which the term first appears. The terms were not found in the art dictionaries listed in Leonardo1 1 , 68 (1978) 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. [ I I , 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. 866. Boolean algebra (in mathematicstA branch of symbolic logic that has applications in the design of computer programs. Logical operations are performed by operators such as ‘and’, ‘or’ and ‘not-and’ in a way analogous to the rules of arithmetic. (11, 13, [14]) 867. Defoamer (inchemicaltec/mology)-A substance added to aqueous solutions and suspensions to reduce the tendency for the formation of foams, for example during the manufacture of water-base emulsion paints or during their subsequent use. (11, 48) 868. Dry-print process (in visual art)-A process by which dried ink on a paper istransferred to a picture surface by rubbing the reverse side of the paper with a suitably shaped tool. (11,45) Electron diffraction (in physics)-A diffraction effect resulting from the passage of electrons through matter. analogous to the diffraction of visible light or X rays. The phenomenon of electron diffraction is the principal evidence for the wave property of electrons. The diffraction ofelectrons when passed through crystals or thin metal foilsis used as a method of investigatingcrystal structure. Electron diffraction isalso used in studies and analyses of substances in the gaseous and liquid states. (11, 10; [14]) (cf. Term 877: X ray digraction and also Terminology, Leonardo 4, 288 (1971): elerlron) 869. 870. Forming fabric (in paper manujucrure)-A stiff fabric, currently of woven monofilament nylon, comprising the continuous belt of a paper-making machine. Fabrics as large as 8 m wide and 40 m long are used to produce newsprint. (11,47) 871. Holding pattern (in oir transportation)-The closed circuits flown near airports by aircraft awaiting clearance to land. (11, 53; [171) 872. Imaginary architecture (in design urchitecluw-Term coined by St. Florian to designate architectural designs that can be conceived and displayed in some manner but that do not take account of the requirements of actual building construction. (I I, 53) 873. Metallography (in physics-A study of the crystalline structure of metals and alloys, especially with a microscope. (I I, 10; [14, 171) 874. Radiography (inphysics and medicine)-The technique of making shadow photographs by passing radiation through an object. X rays and gamma rays are commonly used, however neutron and electron beams are sometimes employed. (11, 10) 875. Scanning electron microscope(inp/iysics)-An electron microscope in which a beam of focused electrons moves across the object with secondary electrons produced by the object and the electrons scattered by the object being collected to form a 3dimensional image on a cathode ray tube (CRT). A photograph of the imageof the object iscalled a scanningelectronmicrograph. (11,47;[14, 171) (cf.Terminology, Leonardo3,98 (1970):cathode ray tube (CRT); 4, 288 (1971):electron) 876. Venn diagram (in logic)-A graph that employs circles to represent relations and operitions between sets and between the terms of propositions by the inclusion, exclusion or partial overlap of the circles.(II, 13; [171) 877. X ray diffraction (in cr.~.stallo;grapl?y)-The scattering of a beam of X rays by the atoms of a crystal that by the interference effect produces a diffraction pattern (for example, recorded on photographic film), which provides information on the structure of the crystal and on the identity of the crystalline substance. (11, 10;[ I 1, 171)(cf.Term 869: electrondij’frurtion and also Terminology, Leonardo 5, 262 (1972): interference) I47 ...