AN EXTRACT FROM THE PREFACE TO THE SECOND EDITION OF THE MATHEMATICAL TRACTS. "The Undulatory Theory of Optics is presented to the reader as having the same claims to his attention as the Theory of Gravitation: namely, that it is certainly true, and that, by mathematical operations of general elegance, it leads to results of great interest. With regard to the evidence for this theory; if the simplicity of a hypothesis, which explains with accuracy a vast variety of phenomena of the most complicated kind, can be considered a proof of its correctness, I believe there is no physical theory so firmly established as the theory in question. This can be felt completely, perhaps, only by the person who has both observed the phenomena and made the calculations; as to my own pretensions to the former qualification, I shall merely state that I have repeated nearly every experiment alluded to in the following Tract. This character of certainty I conceive to belong only to what may be called the geometrical part of the theory: the hypothesis, namely, that light consists of undulations depending on transversal vibrations, and that these travel with certain velocities in different media according to the laws here explained. The mechanical part of the theory, as the suppositions relative to the constitution of the ether, the computation of the intensity of reflected and refracted rays, &c, though generally probable, I conceive to be far from certain. "The plan of this Tract has therefore been to include those phenomena only which admit of calculation. Many subjects are thus excluded (for instance, the absorption of light by coloured media) for which supplementary theories are still wanting. On the other hand, the investigations are applied only to phenomena which actually have been observed: as I have thought it useless to suppose imaginary combinations, where the real conditions of experiment offer so great variety. "The second investigation of the intensity of light reflected from a glass surface, and that of the nature of light reflected internally and totally from glass, were written as a conjectural restoration of Fresnel's investigations, when his paper was supposed to be lost. That paper has since been found and published: the only alteration which it appeared necessary to make is contained in the note attached to the latter."

This book is a long-term history of optics, from early Greek theories of vision to the nineteenth-century victory of the wave theory of light. It shows how light gradually became the central entity of a domain of physics that no longer referred to the functioning of the eye; it retraces the subsequent competition between medium-based and corpuscular concepts of light; and it details the nineteenth-century flourishing of mechanical ether theories. The author critically exploits and sometimes completes the more specialized histories that have flourished in the past few years. The resulting synthesis brings out the actors' long-term memory, their dependence on broad cultural shifts, and the evolution of disciplinary divisions and connections. Conceptual precision, textual concision, and abundant illustration make the book accessible to a broad variety of readers interested in the origins of modern optics.

Excerpt from On the Undulatory Theory of Optics: Designed for the Use of Students in the University This Treatise on the Undulatory Theory of Optics was first printed in the year 1831, as the last Essay in the Second Edition of a series of "Mathematical Tracts;" and was subsequently reprinted, occupying a similar place, in successive editions of that work. At the suggestion of the Publisher, it has now, with my approval, been printed in a separate form. Its arrangement and details are however the same, without material alteration, as in the Fourth Edition of the "Mathematical Tracts." I am happy to state that the work has been passed through the press under the superintendence of Robert Morton, Esq., B.A. of St Peter's College. Every security is thus given for the general accuracy of the publication. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.