* I am indebted to Mr. D. H. Brill and Mr. S. J. Sigel of the Research Staff of the Board of Governors of the Federal Reserve System both for their extensive and constructive criticism and for the many ideas I have absorbed from their unpublished manuscripts which they so kindly made available to me. It proved impossible to give adequate acknowledgment to these papers and the extent to which they are cited below in no way indicates how heavily I have relied upon them. I am also indebted to Professor M. A. Copeland of Cornell University and Mr. J. C. Dawson of the University of Maryland for their extensive comments, criticisms, and suggestions. I alone, however, am responsible for whatever errors remain.