Infiltration of water into soils from a constant circular source was studied through the use of a mathematical model and a physical model. The boundary conditions were selected for the purpose of deducing the soil hydraulic properties from the infiltration process. Infiltration rate was related to the properties of the soil, to the initial condition of the soil, and to the size of the infiltration source. A tentative theoretical equation was presented for determining the pore size distribution of the soil from the infiltration capacity. It is suggested that small scale infiltration experiments in the field may be used to characterize the soils according to their hydraulic properties.