A method is described for the construction of electrical models with which to solve problems of the flow of liquids through porous media under the action of gravity. With these models the shape of the free surface and the extent of the surface of seepage are determined simultaneously with the potential distribution within the flow system. Four examples are given of the application of the method to the problem of the seepage of water through dams. In two cases the faces of the dams were assumed to be sloping, and in the others they were taken as vertical, the free surface and velocity distributions at the faces of one of the latter cases checking closely with those derived from an analytical solution of the problem. The method of applying these models to the study of more complex gravity flow systems is briefly indicated.