This book, published in 1920, is an important contribution to the field of physics. Slater, a professor at Harvard University, argues for a radical new approach to understanding matter and energy, asserting that mechanical motion is fundamental to all physical phenomena. He lays out a comprehensive theory of motion and force, drawing on the latest research and experimental evidence. Although Slater's ideas were controversial in his time, they paved the way for new developments in physics in the 20th century. 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. We appreciate your support of the preservation process, and thank you for being an important part of keeping this knowledge alive and relevant.