Footing Courses. Unless the footing course rests upon solid rock or upon clay, it should be considerably wider than the foundation upon each side, and should be made of large flat rocks, which have a good bearing upon the earth beneath. If a house is built upon a sidehill, the excavation for the footing course should be in steps, as shown in Fig. 5, to guard against slipping down hill.

Fig. 4. - Building a Foundation upon a Ledge.

If the footing course rests partly upon a ledge, the bearings upon the earth should be very broad, in order to furnish as nearly as possible the same resistance as the ledge. In laying the foundation for an ordinary house, the stones frequently are laid dry, and the mortar pushed into the cracks after the wall is entirely laid. This is called "pointing," and is a cheap way of doing work; but it is the method followed commonly in that class of work known as "Jerry building." If the wall is well bonded in laying, this method may be satisfactory for a light dwelling house, but it will never be so safe as if the work had been done properly.

In constructing the foundation for an important building, each stone should be laid in mortar stiff enough to prevent the weight from forcing all the mortar out from the high places between the stones, and allowing the upper stones to rest directly upon those below them. If this happens, the shrinkage of the mortar in drying will leave the upper stones resting upon points, thereby lessening the stability of the wall. Little dependence should be placed upon stone chips, or "spalls," to make a stone rest firmly, as these often work out.

Foundations of heavy buildings sometimes are made of twisted bars, or railroad iron, or of I beams laid crossways in different courses, with concrete worked into all the corners and angles, and thoroughly tamped to form a compact mass.

Fig. 5. - Rubble Foundation., built upon a Hillside.

Concrete for work which is to support heavy loads should be made of 1 part Portland cement, 2 parts sand, and 4 or 5 parts broken stone. A cheaper grade of cement sometimes will give satisfactory results, though it is never so reliable as a standard and carefully tested brand of Portland cement.

7. Stonework. The stonework of a building may be of several different styles of finish, of which we will discuss only those in most common use.

Rubblework is the name applied to rough unhewn stones laid as they may fit each other best. A bond stone should run through the wall about every 5 square feet. Underground foundations of this type are frequently laid. (See Fig. 5.)

Ashlar is the term applied to all stonework which has a finished face. Oftentimes a veneer of ashlar is used as a facing for a rough wall of either stone or brick, and is held in place by bond irons, or by faced bond stones which are built into the wall at frequent intervals.

Coursed ashlar is the term applied to work formed by stones laid as shown in Fig. 6. The horizontal or bed joints are unbroken except at the openings.

Broken ashlar is the term applied to stonework laid as in Fig. 7.

A draft is a line cut around the face of a stone as in Fig. 6, the face being first pitched off so that it is square with the bed.

Fig. 6. - Coursed Ashlar.

Pitch, or rock face, means that the face is cut to a line, or "pitched" square with the bed of the stone and out of wind, leaving the rest of the face as it came from the quarry, or "quarry faced." If a stratified stone is used, such as limestone, it should be laid upon its natural bed, for when the stone is exposed to the weather, it absorbs a great deal of moisture, and if the bed is laid vertically, freezing will cause the layers to scale off.