Book excerpt: A series of specific challenges led Eli Whitney to exercise his ingenuity in technology and made him an engineer. His cotton gin revolutionized Southern agriculture. And the problems of manufacturing large quantities of guns drove him to develop principles important in his own time, and even more important later. The application of those principles would one day give American industry the structure within which it more than fulfilled the ambitions of the Revolutionary generation. This is the absorbing story Constance Green has told through a skillful mingling of personal narrative and technological analysis. - Editor's preface.