The Constitution of the Interior of the Earth as Revealed by Earthquakes

ON p. 45 of Dr. G. W. Walker's recently published book, “Modern Seismology,” I find the following sentence:—“It has sometimes been asserted that S never reaches beyond a certain distance, and to explain this an impenetrable core of the earth has been assumed. We see that no such hypothesis is at all necessary to explain the observations.” The reference here seems to be to a paper, by myself, “The Constitution of the Interior of the Earth as Revealed by Earthquakes,” which was published in the Quarterly Journal of the Geological Society (vol. lxii., 1906), or, more probably, to the references to this paper contained in Prof. Wiechert's paper, “Ueber Erdbebenwellen,” published in the Nachrichten d. K. Gesellschaft d. Wissenschaften (Göttingen, 1907), and as the summary dismissal of the subject indicates an imperfect appreciation of the problem, which is one of the important problems of the immediate future of seismological research, I trust you will afford me space to state the position.