228. A form of construction much used, especially in fireproof buildings, is by means of terra-cotta blocks, as shown in Fig. 92, or hollow brick, as given in Fig. 93. Fig.

92 shows the hollow blocks, which are usually about 2 feet by 20 inches, so they can be fastened to every sixth course of brickwork by wire ties, as shown at b, or bent hoop iron, as at c. The wall, as shown at d in Fig. 93, is 16 inches, or two bricks, thick, and, as the terra-cotta blocks are 4 inches thick, the total thickness of the wall is 20 inches. 2-9

When hollow brick are used for inside furring of outside walls, they are laid as shown in Fig. 93. As the hollow brick are made just the size of ordinary common brick, they can be bonded into the solid brick wall with header courses, just as the common brick are bonded. At a, Fig. 93, appear the header courses of hollow brick, and at b, the stretcher courses; c gives a view of the header courses of common or solid brick; d, the inner brick of the wall between the stretcher courses; and e, the outside stretcher course of the wall.

Fig. 92.

Fig. 93.