Perhaps it would be well to begin by asking ourselves, "What do we mean by a foundation?" the answer is that a foundation is the base upon which the superstructure of a building is built and carried. This being the case, it is of the utmost importance that the foundation be strong and true. Errors made int eh size, shape, or strength of the foundation not only lead to troubles later during construction, but also contribute to instability and early trouble in the building itself. The construction of any type of foundation will involve the removal of earth, the amount depending on the type of foundation. A full basement may require the removal of a considerable quantity of earth, involving hundreds of cubic yards, whereas a flat slab will require relatively little excavating. In the case of a surface or a pier foundation, the excavating may be confined to holes or trenches. The dimensions of the footings must be such that they will safely carry the loads of the building and transmit them over a sufficiently large area of earth beneath. The earth is tested for its load-bearing qualities, which may vary from very little- one-fourth ton per square foot - to over 40 tons per square foot. The building loads must be known so that the footings may be made large enough that the loads are spread over enough bearing area. The kind of material required for footing forms will depend on their size and on whether they are to be constructed above ground level or set into the excavation bottom. If they are to be set above the ground, they should be of 2 inch material to withstand the pressure of the fresh concrete. Footings made below ground level need only three-fourths of an inch material. After the footing concrete is set and at least partially cured, the forms are removed and the job is ready for erection of wall forms. There are a great many methods of building wall forms today, but we shall discuss only a few of the well-known ones. The oldest method consists of making wall frames of 2 inch by 4 inch plates and studs and lining the inside face of each with some type of sheathing- shiplap or common boards. The walls are kept straight by walers which run horizontally from end to end at three or more levels, depending on the height and thickness of the wall. The whole form is held vertical and in position on the footing by a system of bracing.