1. ^**Rudy Professor of Economics, Indiana University, Bloomington
2. ^***Assistant Professor of Economics, University of Cincinnati

^*Of the many persons who have helped us improve earlier drafts we would like to thank, in particular, John Pencavel of Stanford University, Gernot M.R. Winkler of the U.S. Naval Observatory, and Roy J. Gardner, H. Scott Gordon, Roger Newton, Nicolas Spulber, and Willard E. Witte of Indiana University.