This book presents a recasting of Aristotle's theory of spatial displacement of inanimate objects. Aristotle's claim that projectiles are actively carried by the media through which they move (such as air or water) is well known and has drawn the attention of commentators from ancient to modern times. What is lacking, however, is a systematic investigation of the consequences of his suggestion that the medium always acts as the direct instrument of locomotion, be it natural or forced, while original movers (e.g. stone throwers, catapults, bowstrings) act indirectly by impressing moving force into the medium. Filling this gap and guided by discussions in Aristotle's Physics and On the Heavens, the present volume shows that Aristotle's active medium enables his theory - in which force is proportional to speed - to account for a large class of phenomena that Newtonian dynamics - in which force is proportional to acceleration - accounts for through the concept of inertia. By applying Aristotle's medium dynamics to projectile flight and to collisions that involve reversal of motion, the book provides detailed examples of the efficacy and coherence that the active medium gives to Aristotle's discussions. The book is directed primarily to historians of ancient, medieval, and early modern science, to philosophers of science and to students of Aristotle's natural philosophy.

Oliver Heaviside's electromagnetic investigations - from the publication of his first electrical paper in 1972 to the public recognition awarded to him by Lord Kelvin in 1889 - have consistently attracted attention over the years, and of late have become a major source for the study of the development of field theory after Maxwell. "From Obscurity to Enigma" is the only comprehensive, in-depth analysis of Heaviside's work. It analyses and elucidates his brilliant but often close-to-indecipherable Electrical Papers and traces the evolution of his ideas against the background of growing knowledge in basic electromagnetic theory, telegraphy and telephony during these years. The book will be appreciated by historians of science and technology in the late 19th and early 20th centuries and by physicists and electrical engineers, many of whom are aware of Heaviside's contributions to their respective fields.