Excerpt from A Class Book of Physics: Parts IV. And V., Light, and SoundThe standard of each Part of the volume is roughly that which may be expected reasonably of pupils from about fourteen to sixteen years of age. Probably few pupils will work through the complete course, but an endeavour has been made to provide for the requirements of students who intend to present themselves as candidates in elementary examinations in any branch of physics.By the kind consent of Mr. A. T. Simmons, parts of books of which he is joint author have been adapted for use in the present volume. Adequate thanks cannot be expressed for the self-abnegation thus manifested by the friend and long-time colleague of the authors. Most of the illustrations are new, but a few are based upon figures in other books published by Messrs. Macmillan 8: Co., Ltd., to whom the authors are glad to acknowledge their indebtedness.About the PublisherForgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.comThis 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.