An addition and certain changes have been made in this impression. The new member, an Appendix, offers an elementary proof of the existence of a balanced-growth equilibrium in the original von Neumann system. The changes are in relation to views previously attributed to Sir Roy Harrod. He points out that, while some of these views have been attributed to him in other writings, authority cannot be found for them in his own works.
Furthermore, the word 'knife-edge' used in Chapter IV should be understood as synonymous with instability and not as implying extreme instability. In fact, A. B. Atkinson (Review of Economic Studies, 1969) has shown that the instability in the Harrod system is moderate only.
Finally, I would like to express my sincere appreciation of the kindness and assistance which Sir Roy Harrod offered me in correcting some bibliographical slips in the previous impression of this book.