R. Byron Bird is Vilas Professor of Chemical Engineering at the University of Wisconsin-Madison. He is a coauthor of Dynamics of Polymeric Liquids, 2nd Edition, Volume 2 (Wiley 1987), Molecular Theory of Gases and Liquids, (Wiley, 1954), Transport Phenomena, (Wiley, 1960), and several other books. He received his BS in chemical engineering at the University of Illinois in 1947, and his PhD in physical chemistry at the University of Wisconsin in 1950. Robert C. Armstrong is Associate Professor of Chemical Engineering at the Massachusetts Institute of Technology. He is a coauthor of Dynamics of Polymeric Liquids, 2nd Edition, Volume 2 (Wiley, 1987). He received his BChE at Georgia Institute of Technology in 1970 and his PhD at the University of Wisconsin in 1973. Ole Hassager is Lektor at the Danmarks tekniske Hjskole in Lyngby, Denmark. He is a coauthor of Dynamics of Polymeric Liquids, 2nd Edition, Volume 2 (Wiley, 1987). He received his MSc in chemical engineering at the Danmarks tekniske H?jskole in 1970 and his PhD in chemical engineering at the University of Wisconsin in 1973.