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This work has been selected by scholars as being culturally important, and is part of the knowledge base of civilization as we know it. This work was reproduced from the original artifact, and remains as true to the original work as possible. Therefore, you will see the original copyright references, library stamps (as most of these works have been housed in our most important libraries around the world), and other notations in the work.This work is in the public domain in the United States of America, and possibly other nations. Within the United States, you may freely copy and distribute this work, as no entity (individual or corporate) has a copyright on the body of the work.As a reproduction of a historical artifact, this work may contain missing or blurred pages, poor pictures, errant marks, etc. Scholars believe, and we concur, that this work is important enough to be preserved, reproduced, and made generally available to the public. We appreciate your support of the preservation process, and thank you for being an important part of keeping this knowledge alive and relevant.

This work has been selected by scholars as being culturally important and is part of the knowledge base of civilization as we know it. This work is in the public domain in the United States of America, and possibly other nations. Within the United States, you may freely copy and distribute this work, as no entity (individual or corporate) has a copyright on the body of the work. Scholars believe, and we concur, that this work is important enough to be preserved, reproduced, and made generally available to the public. To ensure a quality reading experience, this work has been proofread and republished using a format that seamlessly blends the original graphical elements with text in an easy-to-read typeface. We appreciate your support of the preservation process, and thank you for being an important part of keeping this knowledge alive and relevant.

Excerpt from Optical Measuring Instruments: Their Construction, Theory, and Use I accede with pleasure to the request that I should write a Foreword for the book of my colleague, Dr. Martin, on Optical Measuring Instruments. More especially do I do so, because it was at my invitation that he originally turned his attention to the subject, when the Department of Optical Engineering and Applied Optics was founded at the Imperial College. In Dr. Martin's book the student will find, brought together for the first time, descriptions of a number of well-selected typical instruments, which embody and exemplify in their design, construction, and use, optical principles and devices of great interest and of wide application - information which hitherto it has been very difficult if not impossible to obtain except by reference to the records of the Patent Office, or those of learned societies. This bringing together of cognate matter should be of great value and convenience to everyone interested in the application of optical measuring means to instruments of precision generally. The limitations, for measuring purposes, of the human eye were humorously brought out by a friend of mine - a famous inventor of range-finders - when, some years ago, he deplored the fact that nature had not seen fit to impress our retinas with stereoscopic scales, by means of which ranges could be accurately determined without any instrumental aid. 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.