The difficulties of mathematical analysis of field drainage problems are at present insuperable, but progress may be made by electrical analogy, as the equation of flow of ground water to parallel drain lines is also the equation of 2-dimensional flow of electricity in a sheet conductor. 3 sets of expts. are presented to show (a) how the water-table falls with increase of drain diameter, or alternatively with reduction of drain separation; (b) the relation of water-table height to rate of rainfall; and (c) the influence of the depth of the impermeable floor below the drains. The well-known formula giving an elliptical water table section is not in accordance with the requirments of potential theory. The relation of such laboratory work to practical drainage problems is briefly discussed.