Physiological Optics: Being an Essay Contributed to the American Encyclopedia of Ophthalmology (Classic Reprint) - Softcover

Charles Sheard

Softcover

ISBN 10: 1332287778 ISBN 13: 9781332287772

Publisher: Forgotten Books, 2018

Synopsis

Excerpt from Physiological Optics: Being an Essay Contributed to the American Encyclopedia of Ophthalmology

Through the courtesies of Dr. Casey A. Wood, Editor-in-chief of The American Encyclopedia of Ophthalmology, and the publisher, Dr. Geo. Henry Cleveland, of the Cleveland Press, the writer of this monograph has been able to secure a limited number of reprints of the original essay for the use of students and practitioners who may be interested in the field of physiologic optics.

The body of the text is in the form presented in Volume XIII of the Encyclopedia. Certain references to other volumes of the set have been changed in this reprint and a few additions deemed necessary by virtue of the isolation of this essay from its context have been placed in the Appendices.

The present volume is neither a mere compilation nor does it consist of abstract theoretical discussions, but is a collection of the old and new scientific facts that have bearing upon the practical work of the refractionist and eye-practitioner. I hope that the reader will pardon any indulgence in details relative to some of the topics presented, but I feel that far too little attention is paid, in many cases, to the fundamentals and essentials underlying the science of optics as applied to visual phenomena and that a closer and keener study of these vital details will help make the "practical" man of the right type.

I take pleasure in acknowledging my indebtedness to various authors and publishers who have put at my disposal, through the medium of the printed page, such materials as have helped greatly to make this volume what it is. I have drawn freely from the writings of von Helmholtz, Tscherning, Maddox, Stevens, Howe and Savage. In particular do I acknowledge the permission granted by the Editor and the Publisher of The American Encyclopedia of Ophthalmology, The Keystone Publishing Co. of Philadelphia, Dr. Savage, Dr. Howe, Dr. Stevens and Chas F. Prentice, M. E., to have reproduced, or to use the original cuts of, several diagrams and drawings from their books.

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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.

About this title

Product Description

Excerpt from Physiological Optics: Being an Essay Contributed to the American Encyclopedia of Ophthalmology

These four fundamental experimental facts as to the direction of rays Of light are comprehended in a general way in a Single law Often referred to as the principle of least path or Fermat's principle of least time. If a ray of light passes from a point A to a point B and suffers any number Of reflections and refractions, then the sum of the products of the index of refraction (n) Of each medium multiplied by the distance traversed (l) in it differs from a like sum for all other paths which are infinitely close to it by terms Of the second or higher order; i. E., the variation in the total paths, optically considered, approaches zero. This principle finds frequent and important appli cation in geometrical optics. The four fundamental laws above enumerated relate only to geometrical determinations of the prope gation of light and constitute, therefore, a sufficient basis for geo metrical Optics. We shall assume their validity and proceed to use them in the deductions Of ocular constants and data.

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.

Edition details

• Publisher: Forgotten Books
• Publication date: 2018
• Language: English
• ISBN 10: 1332287778
• ISBN 13: 9781332287772
• Binding: Paperback
• Number of pages: 521