The report concentrates on (1) describing mathematically soil-plant-atmosphere systems in terms of water balance and continuity of mass equations and (2) working with analog computer theory and programming techniques for modeling above relations. The investigation suggests many possible applications in forest hydrology as well as applied and basic hydrology. General principles and methods of analog computer simulation are discussed. Examples of hydrologic models are presented, including surface flood runoff, a model for vertical transport processes from the forest cover to the soil system and a program for modeling one-dimensional soil-water flow with time. The models illustrate the capability and potential of analog simulation in forest hydrology. Verification was not attempted due to insufficient input data and the difficulty of converting discrete digital input data into analog input signals. Limitations and advantages of digital and analog simulations are discussed. (Wooldridge-Wash)