The Theory of Modern Optical Instruments is a book written by Alexander Wilhelm Gleichen in 1921. This book is a comprehensive guide to the theory and design of modern optical instruments, including telescopes, microscopes, and other optical devices. Gleichen's work is based on the latest research and developments in the field of optics, and he provides a detailed analysis of the principles and operation of these instruments. The book covers topics such as lens design, aberrations, diffraction, polarization, and the use of optical instruments in various scientific fields. Gleichen's writing is clear and concise, making this book an accessible resource for students and professionals alike. The Theory of Modern Optical Instruments is a valuable reference for anyone interested in the history and theory of optics, as well as those working in the field of optical engineering.This scarce antiquarian book is a facsimile reprint of the old original and may contain some imperfections such as library marks and notations. Because we believe this work is culturally important, we have made it available as part of our commitment for protecting, preserving, and promoting the world's literature in affordable, high quality, modern editions, that are true to their original work.