Having briefly referred to the preliminary drainage, and some methods of ascertaining the nature of the ground, the former to lessen, and the latter to aid discovery of the character of any probable upward lushes of soil: “boils” in foundations are more specifically considered. It may be said that they generally proceed from an impervious top stratum being pierced, thereby tapping the water in a pervious bed which may be imposed upon another impervious layer; for the upper bed being excavated removes the weight upon the lower strata and induces a flow of the previously confined water. The source of disturbance may be either from surface-water in the top soil or from deep underground springs, depending in great measure upon the extent of the catchment area and head-water level of the district, as its quantity and uplifting pressure will be principally governed by them. When the soil is in a delicate state of equilibrium it only requires a slight deteriorating alteration of the normal condition to initiate a movement. The disturbance of the ground may be merely superficial, nevertheless its effect may be sufficient to start a “boil,” although the chief cause potently exists at some considerable depth and distance. “Boils” produced by simply surface-water require one system of treatment; if from underground waters, another remedy is necessary. Every effort should be made to know the reason, trace the origin, and to ascertain the power of the disturbing forces. It may be possible to determine them, although generally it can only be done by deductive reasoning and logical inference. In any event immediate action is invaluable when a “boil” appears. Weighting the ground around a “boil” with an impervious mass of clay, and the insertion of a stand-pipe will indicate the level to which the water will rise, varying according to the seasons, and will give an approximate idea of the head supply and pressure; care being taken that the pipe does not become obstructed and that the water has a free flow. It may also be ascertained by the insertion of pipe-rods to different depths, and by noticing the effects, such as the rapidity, the quantity and the character of the discharge. There may be an appreciable difference in the height to which the water rises in various stand-pipes; if so, its flow is obstructed or the source is not identical. An examination of the colour and nature of the suspended matter in the water and a comparison of it with the strata may show its source, but it is not always reliable unless the same colour is maintained for the lowest depths.