Optics, Painting and Photography by M. H. Pirenne (review)

Books 397 venience of this absolute space by adopting, for practical purposes, a relative space of measurement that served Newtonian physics adequately for two centuries and the mechanics of the engineer to this day. The last, longest and most important chapter treats brilliantly of the concept of space in modern science. Here some adjustment must be made in view of the important change in scientific attitude that took place in this century. The scientist sees himself as formulating communicable structures of understanding in his mind, having abandoned as unrealisable the pretence of objective observation of external phenomena, unaffected by his action. We could see this as input of information to a pre-existent field; the results coded symbolicallyas an external structure on which further action can be undertaken leading to more patterns of understanding . Recent work in electro-encephalography (EEG) suggestseventhe typesofrhymthicpatterns involved and oscillographs can be devised to reproduce certain of these rhythms that can be fed back exceptionally to trigger further reactions. The assumed coherence and reproducibility of such patterns beyond simple chance might be deduced from a correspondence analogy or even a common source in the brain and in the cosmos. Yet, Jammer shows that modern field theory of space arises from geodetic practice as Euclidian geometry did from land surveying and trigonometry from navigation. Throughout, he demonstrates the search for simplicity, for a unifying principle. He reveals to us the purely aesthetic pleasure to be obtained from the singularity of the time axis in coordinate systems; in Riemannian concepts of wave-ripple in time; the beauty of the intrinsic assymetry of time-space and Clifford‘s elegant concept of substance as the accident of space. Optics, Painting and Photography. M. H. Pirenne. Cambridge University Press, London, England, 1970. 199pp., illus. 54-00.Reviewed by: John M. Kennedy* M. H. Pirenne, respected physiologist of vision, has brought experimental skills to bear on Optics, Painting andPhotography. He presents an argument, beginning with an empirical finding. Point leads to point with the aid of splendid illustrations and empirical findings, and the illustrations allow readers to test for themselves the validity of his claims. No monograph today can do justice to all of the overlap between optics, painting and photography , and, wisely, Pirenne’s book has a central theme. The kernel is an important problem in picture perception, namely perspective. In fact, ‘Perspective and Perception’ would have been a *Department of Social Relations, William James Hall, Harvard University, Cambridge,Mass. 02138, U.S.A. 28 more apt title. The kernel problem is that pictures are not viewed only from points to which they cast geometrically correct projections, yet the resulting perceptions rarely seem distorted. This problem he treats carefully, beginning with an analysis of projective geometry in the optics that allow perception of real scenes. Pirenne lucidly describes the origins of views on perspective and vision, beginning with Euclid and going to Kepler and da Vinci, for example, and then to Helmholtz. The latest view is that optical structure at any point wherethe observermight place his eye is tied to its origins in the world by the rectilinear travel of light, sothere is a basis on which someone accepting the light might determine the origins, that is, ‘seethe stimulus’. Objects project particular perspective shapes to particular points of observation, for example, any sphere projects a symmetrical cone of light to a point. Let a plane surface be placed between an observation point and several spheres. If the surface is at right angles to the axis of a cone of light from a sphere, then the intersection of the cone with the surface will be a circle. If the surface is not at a right angle, the intersection will be an ellipse. One might think that the plane surface would provide a good representation of the spheres, if it were painted with the shapes of the intersections, for then the painted areas would cast the same cones of light to the observation point. This is perfectly true, if one restricts one’s vision to a peephole at the observation point. If one does not look from quite the right place, then the ellipses do not look like appropriate representations but, paradoxically...