Text-Book of General Physics for High Schools and Colleges (Classic Reprint)

Book excerpt: Excerpt from Text-Book of General Physics for High Schools and Colleges The Ether. - A careful study of the phenomena of light led philosophers many years ago to the belief that there is present in space another medium for phenomena than that furnished by ordinary matter. As we shall see later, there is every reason for believing that throughout the vast regions of space in the solar system, and beyond, ordinary matter is absent, except in certain cases as thin atmospheres around the planets and stars; it is also known that the sensation which we call light is due to the fact that waves enter the eye; therefore, when one sees a star, one has evidence that waves have left the star and have crossed space void of ordi nary matter. There must be present, then, in this space a medium that can carry waves: it is called the ether (sometimes and its properties will be discussed more fully in what follows. Similarly, in order to explain many electrical and magnetic phenomena, it was necessary to assume the existence of a medium different from ordinary matter, and one of the great achievements of the last century was the proof that this medium was the ether. There is, moreover, at present no evidence of the existence in our uni verse of any other media than ordinary matter and the ether. 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.