Scattering of X-ray Quanta and the J Phenomena

Abstract

IN NATURE of November 17, p. 723, Prof. Barkla discusses the transformations of X-rays during scattering and transmission through matter, with particular reference to my recently proposed quantum theory of X-ray scattering. Permit me to present my apology to Prof. Barkla for not referring to the work done on this subject by himself in 1904 (Phil. Mag. 7, 550), and by Beatty in 1907 (Phil. Mag. 14, 604) working in his laboratory. This early work was not mentioned because of later statements of his, such as, “the scattered radiation differs inappreciably in penetrating power from the primary radiation, that is to say, there is no appreciable degradation accompanying the process of scattering” (Barkla and Ayers, Phil. Mag. 21, 271, 1911). These statements led me to think that Barkla judged the differences between the primary and the scattered X-rays observed in these earlier experiments to be smaller than the experimental error.