The Influence of Soil Characteristics on Drainage and Irrigation Practices

the equation is adapted to a broader application. The tensile strength, the shearing strength, the bearing strength, the binding strength, the plasticity, are soil characteristics which are important to engineers, and, from an academic point of view, there are other interesting constants depending upon the fundamental physical and chemical nature of the soil. The hygroscopic coefficient, the wilting coefficient, and the moistureholding capacity, seem to have more or less practical significance, and, because of its precision, the moisture equivalent has come into general use. Briggs (1) has shown, however, a simple interdependence of these characteristics, and Buckingham (2) has devised the notion of a capillary potential function which varies continuously (in a macroscopic sense) with the moisture percentage of the soil. Richards, (8) working in the Utah laboratories and later at Cornell, presents data showing this relation over a considerable range for a. fine, a coarse, and an intermediate soil. His results are