The strength of a brick wall depends not only upon the bricks, the mortar, and the workmanship, but the assembling of the different members, the bond or arrangement adopted for tying together the separate parts, and also for distributing the effects of concentrated loading. The common bonding consists of laying every fifth or sixth course of bricks at right angles to the direction of the wall, as in Fig. 107. These courses are called header courses and serve to tie the wall together. Where the wall is faced with pressed brick and the regular occurrence of header courses would not look well, the face work is tied to the backing by clipping off the back corners of the face bricks, and inserting a course of diagonal headers. (Fig. 108.) Galvanized steel ties of patented manufacture are extensively used in the East and are effective for this purpose. English bond is a bonding much used in England and consists of alternate courses of headers and stretchers, as in Fig. 109.

Fig. 105. Struck Joint.

Fig. 105. Struck Joint.

Fig. 106. V Joint.

Fig. 106. V-Joint.

Fig. kit. Common Bonding of Brick.

Fig. kit. Common Bonding of Brick.

Flemish bond, Fig. 110, consists of alternate headers and stretchers in each course. This bond is sometimes used effectively in facings of common brick, by using blackened headers, and it is sometimes used for every fifth course of face work instead of the diagonal headers. The bonding of angles is an important matter, and, in addition to the regular bond, most of the city laws require that the corners shall be tied with iron straps or bolts. In joining new work to old, however, direct bonding should he avoided for fear of unequal settlement, and some such method as shown in Fig. 111 should be adopted.the same amount of brickwork, independently of the air space, in hollow walls, as is required in solid walls, so that there is a loss of space which must be considered in city building.