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Synopsis A clay with near perfect particle parallelism was prepared by consolidating a slurried kaolin in a large oedometer. Shear box samples trimmed at various angles to the compression direction revealed no significant difference in drained strength. Samples with original bedding normal and parallel to the shearing direction were interrupted at various displacements and thin sections prepared after impregnation with Carbowax. The sequence of microscopic shear structures shows that in both cases the features at peak strength result from simple shear conditions and that a continuous horizontal structure appears only towards the residual stage. Intermediate structures are interpreted in terms of the kinematic restraint imposed by the configuration of the box. Detailed examination of the development of kink-bands and compression textures lead to the notion of basal plane slip as the basic mechanism in shear induced structures. Une argile ayant une orientation préférentielle quasi-parfaite a été préparée en consolidant une boue de kaolinite dans un œdomètre de grand diamètre. Des échantillons de cisaillement direct taillés suivant différentes orientations par rapport à la direction de consolidation produirent des résistantes au cisaillement comparables. Des échantillons à litage parallèle et perpendiculaire à la direction de cisaillement furent interrompus à plusieurs étages de déplacement, impregnés de Carbowax et découpés en lames minces pétrographiques. La succession des microstructures de cisaillement montre que dans les deux cas leur aspect à l'instant de la résistance maximum résulte de conditions de cisaillement simple, et qu'une structure horizontale continue n'apparait que vers la résistance résiduelle. Les structures intermédiares sont interprétées en fonction de la restriction cinématique imposée par la configuration de l'appareil à cisaillement. L'observation détaillée du développement de plis en S (kinkbands) et des textures de compression ammène à envisager le glissement suivant le clivage basique comme le mécanisme de base des structures de cisaillement.

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The mental processes that al-low an artist to transform visual images-e.g. those of his model-into a picture on the canvas are not easily studied. The authors re-port work measuring the eye and hand movements of a single artist, chosen for his detailed and realis-tic portraits produced from life. His eye fixations when painting or drawing were of twice the duration of those when he was not painting and also quite different from those of novice artists. His eye-hand co-ordination pattern also showed dif-ferences from that of novices, be-ing more temporally consistent. This preliminary work suggests that detailed and quantitative analy-sis of a working artist is feasible and will illuminate the process of artistic creation.