Bruce S. Eastwood, Ph.D. (1964) in History, University of Wisconsin, is Professor of History at the University of Kentucky. He has published, with Gerd Grasshoff, Planetary Diagrams for Roman Astronomy in Medieval Europe (American Philosophical Society, 2004).

The astronomy of the Carolingian era has commonly been represented as concerned exclusively with computus, the science of calendar construction as well as arithmetical calculation in general. This volume shows the error of that portrayal by exploring the study and teaching of four Roman texts on astronomy and cosmology in the Carolingian world and the diagrams connected to those texts. As each of these works came into use over the Carolingian era, its contributions merged into a progressively more ordered picture of the heavens. Both eccentrics and epicycles appeared by the 840s. These techniques were subsequently introduced clearly and qualitatively to complete the Carolingian enterprise. The primary tool for understanding this effort is the analysis of their diagrams.