RAYS ARE NOT COLOURED
Newton first understood, more than 200 years ago, that “the Rays, to speak properly, are not coloured,” and “Colours in the Object are nothing but a disposition to reflect this or that sort of Ray more copiously than the rest…” Yet colour seems so compellingly to be a property of an object that few among us doubt the obvious. Indeed, the insights of Newton, supported by two centuries of scientific elaboration, are not fully appreciated even by the practitioners of colour, such as the artist and the paint manufacturer, let alone the man in the street.
W.D.Wright is a physicist and one of the fathers of the CIE (Commission International de l’Eclairage) system of colour specification. Despite the proven usefulness of this system, Wright admits that it “does not give precise information about the spectral composition of the light or any exact information about the sensation…” Accordingly, Wright’s interests, reflected in this book, have extended well beyond classical colourimetry to the use of colour in art and television, the teaching of colour in schools, and the practical and theoretical problems presented by colour-defective vision.
The difficult problem raised by the coloured appearance of objects provides a recurring theme for some of the nine essays of this slim volume. Is it possible that the man in the street is right to believe what he sees? Wright struggles hard to find a proper basis for restoring colour to the object. He notes that the main task of vision, for which colour is not necessary, is to render objects visible. Although the initial basis for colour vision does lie in the spectral modification of light by the object – just as Newton discerned – such modified light is far from the only basis for colour perception.
Somehow, Wright says, colour projects light back out to, is modified by, and becomes an inherent property of the object. Most of the book consists of the texts of invited lectures delivered from 1951 to 1966. It is easy to see why Wright is so often asked to speak. His remarks are lucid and reflect his enthusiasm for a subject with which he has had more than 40 years of experience. Most of the material will be readily understood by the non-expert. The lectures point more to problems than solutions since they do not attempt to deal with a large percentage of the experimental evidence bearing upon the topics discussed.