First published in 1914, this volume contains a detailed treatise on two different types of gear: worm gears and spiral gears. A worm gear refers to a gear where a worm (a gear in the form of a screw) meshes with a worm gear (similar in appearance to a spur gear). A spiral gear is a type of bevel gear that contains helical teeth. Written in clear, simple language and containing useful diagrams and tables, this volume will prove to be an invaluable resource for anyone with an interest in the design and construction of gearing. Contents include: "Principal Rules and Formulas for Designing Spiral Gears", "Formulas for Special Cases of Spiral Gear Design", "Herringbone Gears", "Methods for Forming the Teeth of Spiral and Herringbone Gears and Worms", "Hobs for Spur and Spiral Gears", "Calculating The Dimensions of Worm Gears", "Allowable Load and Efficiency of Worm Gears", "The Design of Self-Locking Worm-Gears", etc. Many vintage books such as this are increasingly scarce and expensive. It is with this in mind that we are republishing this volume now in an affordable, modern, high-quality edition complete with the original text and artwork.