In Technology in the Industrial Revolution, Barbara Hahn directs the methodologies and questions of the historian of technology to the big question in economic history: Why did the Industrial Revolution begin in England during the eighteenth century, heralding with it the advent of modern economic growth? Hahn takes the archetypal example of a transformed industry as her case study: textiles in northwest England between 1760 and 1840. At the start of this period, cotton constituted less than 1 percent of British industrial output by value; by 1840 it constituted 10 percent. Impressive enough, but this occurred over a period when overall industrial output almost quintupled. Although readers are well served by internalist guides explaining how the new industrial machinery worked from a strictly mechanical perspective, there is surprisingly little in the way of a contextual analysis—detailing how this new machinery was made to work in reference to government regulation, consumer demand, social norms concerning labor practices, gender, and so on. It is “a universe too vast to sketch” (187), but in only a short book Hahn does a superlative job in doing precisely this. In particular, the book is packed with detail, evocatively presented. For instance, to illustrate the sophistication of the preindustrial marketplace, we are witness to the cloth market in Leeds. Initially held in the open air, deals were struck in whispers so that both sides could keep the details a secret. When the market moved indoors to Leeds Cloth Hall, the windows were built especially large so that vendees could still judge the quality of the goods. Conversely, factories were built without windows when the owner wanted to keep some method or device a secret.