“A brilliant history of technology. . . . full of wonders of nature, human invention, history” and more (Wall Street Journal). There is no part of our bodies that fully rotates—be it a wrist or ankle or arm in a shoulder socket, we are made to twist only so far. And yet there is no more fundamental human invention than the wheel—a rotational mechanism that accomplishes what our physical form cannot. Throughout history, humans have developed technologies powered by human strength, complementing the physical abilities we have while overcoming our weaknesses. Providing a unique history of the wheel and other rotational devices—like cranks, cranes, carts, and capstans—Why the Wheel Is Round examines the contraptions and tricks we have devised in order to more efficiently move—and move through—the physical world. Steven Vogel combines his engineering expertise with his remarkable curiosity about how things work to explore how wheels and other mechanisms were, until very recently, powered by the push and pull of the muscles and skeletal systems of humans and other animals. Why the Wheel Is Round explores all manner of treadwheels, hand-spikes, gears, and more, as well as how these technologies diversified into such things as hand-held drills and hurdy-gurdies. Surprisingly, a number of these devices can be built out of everyday components and materials, and Vogel’s accessible and expansive book includes instructions and models so that inspired readers can even attempt to make their own muscle-powered technologies, like trebuchets and ballista. Appealing to anyone fascinated by the history of mechanics and technology as well as to hobbyists with home workshops, Why the Wheel Is Round offers a captivating exploration of our common technological heritage based on the simple concept of rotation. From our leg muscles powering the gears of a bicycle to our hands manipulating a mouse on a roller ball, it will be impossible to overlook the amazing feats of innovation behind our daily devices. Praise for Why the Wheel Is Round “Reading this book, I found myself being pulled along by the curiosity of Vogel as he connects the power provided by the muscles of humans and animals with the immense variety of rotating objects invented over the course of human history. Despite the book’s title, wheels are only one part of the story. Firmly grounded in Vogel’s deep understanding of physical principles, the book is as informative as it is entertaining.” —Richard Marsh, Brown University “This book, like Vogel’s previous titles, is written in a conversational style that makes it accessible to laypeople and undergraduates, even though it addresses complex topics. It is appealing both as a popular science title and as an educational reading tool for graduate students, faculty, and other researchers interested in the field of biomechanics. Recommended.” —Choice