Abstract
THIS book has been written at the desire of Prof. Wallon's students, to whom a graceful tribute is paid, in the preface, for the assistance which their questions, doubts and objections have rendered in developing the author's methods of teaching. To look on one's students as collaborators, that is certainly the secret of successful teaching; and, as here presented, Prof. Wallon's lectures are certainly successful in giving a systematic and clearly defined outline to the science of geometrical optics. The diagrams are well drawn and numerous, and the mathematical proofs are simple and yet sufficient. There is, however, little that is novel to be found in the course of these lectures; indeed, in a few cases it might be objected that there was a tendency to lag behind the times. Thus, in discussing refraction equivalents, Newton's law, that n2 - 1/d = constant, and Gladstone and Dale's law, that n - 1/d = constant, are alone mentioned (n being the refractive index, and d the density of the substance). Lorenz's law, that n2 - 1/(n2 + 2)d stant, is now most generally accepted. For gases, in which n is nearly equal to unity, all three laws hold with about equal accuracy. But Lorenz's law appears to hold in passing from the gaseous to the liquid state, and must therefore be accepted as the most general.
Leçons d'Optique géométrique à l'Usage des Élèves de Mathématiques spéciales.
Par E. Wallon, Professeur au Lyéee Janson-de-Sailly. Pp. 343. (Paris: Gauthier-Villars, 1900.)
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E., E. Leçons d'Optique géométrique à l'Usage des Élèves de Mathématiques spéciales . Nature 62, 30 (1900). https://doi.org/10.1038/062030a0
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DOI: https://doi.org/10.1038/062030a0