Beginning of Quantitative Hydrology

The contributions of three seventeenth century scientists, and their influence on the development of hydrology are reviewed. Not until the latter half of the seventeenth century was a concerted attempt made to establish fundamental hydrological principles on an experimental basis. Pierre Perrault proved by experimental investigations that rainfall is adequate to sustain river flows. His concept was affirmed by Edmé Mariotte, who used precise field investigations. The pluvial theory of springs, however, attracted considerable opposition. Edmond Halley, by his pioneering experiments on evaporation, proved that enough water is evaporated from the oceans to come down as rainfall to sustain the river flows. Thus, the present-day concept of the hydrologic cycle was established by the experimental investigations of Perrault, Mariotte, and Halley.