Earl Logan Jr. is Professor Emeritus of Engineering in the Mechanical and Aerospace Engineering Department at Arizona State University, Tempe, where he is active in teaching, consulting, and writing. An Associate Fellow of the American Institute of Aeronautics, a Life Fellow of the American Society of Mechanical Engineers and a member of the Society for the History of Technology, he is the author of Turbomachinery, Second Edition and the editor of the Handbook of Turbomachinery (both titles, Marcel Dekker, Inc.). He is also the author or coauthor of numerous professional papers that reflect his research interests in basic and applied fluid mechanics. Dr. Logan, a registered aeronautical engineer, received the B.S. (1949) and M.S. (1958) degrees in mechanical engineering from Texas A&M University, College Station, and the Ph.D. degree (1961) in mechanical engineering from Purdue University, West Lafayette, Indiana. He also received the B.A. (1987) and M.A. (1993) degrees in German, and the B.S. degree (1996) in history, from Arizona State University, Tempe.