I. Bernard Cohen (1914—2003) was Victor S. Thomas Professor, Emeritus, of the History of Science at Harvard University, where he taught from 1942 to 1984. He was the first American to receive the degree of Ph.D. in the History of Science. He was the author of many books, including Science and the Founding Fathers: Science in the Political Thought of Thomas Jefferson, Benjamin Franklin, John Adams, and James Madison; The Science of Benjamin Franklin; Revolution in Science; The Newtonian Revolution; The Birth of a New Physics; and, with Anne Whitman, Isaac Newtonís Principia: A New Translation of Newtonís Mathematical Principles of Natural Philosophy. He edited several series of works, including Harvard Monographs in the History of Science, Three Centuries of Science in America, and the ongoing Studies & Texts in the History of Computing. He was a Fellow of the American Academy of Arts and Sciences, the American Association for the Advancement of Science, the Royal Astronomical Society, the British Academy, and the Accademia Nazionale dei Lincei. Richard S. Westfall was Distinguished Professor Emeritus of History and Philosophy of Science at Indiana University, where he taught from 1963 to 1989. His books include Science and Religion in Seventeenth-Century England; The Construction of Modern Science; Force in Newtonís Physics; Never at Rest: A Biography of Isaac Newton; Essays on the Trial of Galileo; and The Life of Isaac Newton. He was a Fellow of the American Academy of Arts and Sciences and of the Royal Society of Literature.