PRELIMINARY NOTICE THE present volume contains the memoirs on the subject of "N" rays, communicated to the Academy of Sciences by Prof. R. Blondlot. The papers have been reprinted exactly as they were originally published in the Comptes Rendus of the Academy. The notes at the end were added later, with the object of throwing light on certain points which were obscure at the time the papers were communicated to the Academy. The title of the first memoir in this collection, "On the Polarization of 'X' Rays," will hardly cause astonishment when it is realized that the study of the "X" rays led the author to recognize the existence of radiations of a totally different character. To these he gave the name of "N" rays. Before the distinction of these two kinds of radiation was made, He some confusion was bound to arise between the phenomena appertaining to each. In particular, the preliminary researches which the author had made' on the velocity of propagation of "X" rays apply in reality not to "X" rays, but to but to "N" N" rays. had found that the velocity of propagation was the same as that of Hertzian waves, and consequently of light. Since the properties of "N" rays, taken in their entirety, do not leave any doubt that these rays are a variety of light, this determination of their velocity is now nothing more than a verification of an assured fact. Nevertheless, this verification seemed not altogether superfluous; it proves at least that the experiments have been carried out with care. 1 Comptes Rendus, t. cxxv. pp. 666, 721, 763. INTRODUCTION BY THE TRANSLATOR In writing this English version of Blondlot's communications to the French Academy, the translator's constant endeavour has been to preserve that simplicity and straightforwardness which render the original a model of scientific exposition. That this object has been attained he will not venture to assert, but he hopes that, at any rate, the reader will be enabled to follow the successive stages of thought in the mind of the discoverer as he progresses from experiment to experiment in a hitherto unexplored domain. If this hope be fulfilled, the book will be welcome not only to those who desire to make acquaintance with "N" rays, but also to all lovers of scientific research, as well as to beginners who wish to attain to scientific methods. The translator has to thank sincerely Professor Reinold, who has been kind enough to revise the translation, and suggest several valuable improvements. ON NEW SOURCES OF RADIATIONS TRANSMISSIBLE THROUGH METALS, WOOD, ETC., AND ON NEW ACTIONS PRODUCED BY THESE RADIATIONS . ON THE EXISTENCE OF SOLAR RADIATIONS CAPABLE OF TRAVERSING METALS, WOOD, ETC. . ON A NEW ACTION PRODUCED BY "N" RAYS, AND ON NEW ACTIONS PRODUCED BY 66 N" RAYS; GENE- ON THE STORING OF "N" RAYS BY CERTAIN BODIES ON THE STRENGTHENING ACTION OF A BEAM OF FERRED ON CERTAIN BODIES BY COMPRESSION, AND ON THE SPONTANEOUS AND INDEFINITE EMISSION OF "N" RAYS BY HARDENED STEEL, |