Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Economics and Social Science, 1963.Vita.Includes bibliographical references.The first essay is concerned with evaluating a stream of utility which extends into the infinite future. In it are derived sufficient conditions on a preference ordering to permit the definition of a continuous utility function as well as, the implications of various axiom sets with respect to preferences in the timing of utility. In the second essay, the time profiles of various economic variables in a neoclassical model are related to two indices of technical change, characterizing the rate and bias of this change. These relationships are used to discuss sufficient conditions for exponential growth and the movement over time of the factor-price frontier. In the third essay is derived the optimal growth path for a model described by T. N. Srinivasan, which has fixed coefficients but many types of capital goods.by Peter Arthur Diamond.Ph.D.