Excerpt from Refraction and How to Refract: Including Sections on Optics, Retinoscopy, the Fitting of Spectacles and Eye-Glasses, Etc The chapter on Prisms has been very much enlarged, as the average book on Ophthalmology gives but little information on this branch of refraction, and, to make it more entertaining, the writer has not limited himself to the consideration of prisms in ophthalmic practice alone, and has inserted many illustrations to make the text easy of comprehension. The Author's double prism, a new and delicate test, for the detection of errors of muscular 1mbalance whether of small or great amount, is incorporated in the text. Among the other entirely new matter in this book mention may be made of Retinoscopy without a cycloplegic (chapter Among the deletions are: Schein er's Test; The Pointed Line Test; The Chromo-aberration Test, and Thomson's Ametrometer, all of which are out of date and relegated to the historical. Many of the illustrations were drawn or photographed by the Author, and the diagrams of astigmatic eyes, as also several others, are original. A Chinese Edition of Refraction and How to Refract, translated by Dr. James H. Ingram of Tungchou, China, was published in October, 1914. 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.