IN this admirable little work Mr. Collier has succeeded in bringing clearly into view the helpful relation in which science may stand to the Arts of Design-sculpture, drawing, and pre-eminently painting. The aim of the primer is to give the outlines of such knowledge of the artistic field of vision, of the visual powers, and of the means of delineation, as may best aid the student to acquire that power of strict imitation of natural objects which is the artist's first qualification.The notion hitherto prevailing and perhaps somewhat superciliously held to on the part of art-that because the primary functions of science and of art respectively are widely different, therefore no legitimate help can be rendered by one to the other-is practically discredited in every page of Mr. Collier's little work. Throughout, his object is to pioneer the student to an artistic goal; throughout, the means employed have all the security of clear scientific principle. The theory of the Primer is that by knowing with scientific accuracy how some things are, the task of exhibiting artistically how other things appear may be greatly simplified.After devoting a few charming pages to the latest suppositions concerning the origin of sculpture and drawing -pages illustrated by specimens of prehistoric and even Paleolithic art-Mr. Collier quits "debatable ground" for that on which surer scientific light can be shed for the guidance of the student in the practice of art.And here nothing is overlooked. Boundaries, Light and Shade, Texture, Perspective, Color, and Contrast are the headings of so many terse and luminous little chapters, through each of which comes some word to the learner from the invisible world where science works, warning him how, unless he gives heed to certain hidden actualities within and without him, he may and probably will go many times wrong before he lights on the best way of rendering the natural objects before him.Accurate seeing is necessary to ensure accurate delineation. The facts of simple appearance are what the art student needs to lay hold of. Science, whose constant business is with facts of every order, aids him here with suggestions how to discriminate between sight and inference-between that actual aspect of an object which is due to its present relation to the sight of the observer, and that compound mental view of it which is due to the mixed memory of many previous aspect. A perusal of Mr. Collier's pages on the nature of perspective, on the undulatory theory of light, on the action of a lens, on the structure and nervous mechanism of the eye, and on the physiological rationale of the phenomena of color show how much scientific information can be given without the use of a single technical phrase.-"Nature," Vol. 26