Irving Fisher's Ph.D. thesis, submitted to Yale University in 1891, contains a fully articulated general equilibrium model presented with the broad scope and formal mathematical clarity associated with Walras and his successors. In addition, Fisher presents a remarkable hydraulic apparatus for...

Portfolio theory has been an important component of open economy macroeconomic models. In those models, it is essential to distinguish among several categories of assets, both foreign and domestic, and to specify the demands and supplies. This framework has become increasingly relevant....