Prologue.- Synopsis.- One Basic Kinematics of the Gear Set.- Two The Fundamental Law of Gearing.- Three Mating Involute Helicoids.- Four Key Aspects of the Geometry.- Five (A) The Simplicity of Equiangularity.- Five (B) Synthesising an Equiangular Set.- Six The Plain Polyangular Option.- Seven Worm Drives Offset and Non-Offset.- Eight Exoticism by Accident or Design.- Nine (A) Helicality Tight Mesh and Backlash.- Nine (B) Mechanics of the Phantom Rack.- Ten Mathematics of the Machining.- 11 Aspects of the Physical Reality.- 12 The Screw Systems and Gear Design.- Table of Numerical Results.- Notes and References.- Symbols Index Including List of Acronyms Subjects and Authors Index Alphabetical.