Recognizing the present need for up-to-date and reliable information on instrumentation for continuous recording of magnetic properties, the ASTM Committee A-6 on Magnetic Properties appointed a Task Group on Hysteresigraphs (TG-80). The primary mission of TG-8 was to publish as soon as possible a readable monograph summarizing the state of the art of magnetic hysteresigraphs. The present monograph on Direct-Current Magnetic Hysteresigraphs is the result of this effort.