Samuel Slater constructed the first waterpowered machinery in the United States in 1790. Slater Mill, however, was characterized by the mixture of new technology and old methods, and embodied the change and continuity of the industrial revolution. One would think that all the important facts about his factory had been unearthed by generations of scholars. It however occurred to me that a new approach to the old Slater Mill is feasible through the examination of forms and contents of account books. They provide another testimony of the continuity and discontinuity of the American industrial revolution.