Flues should be cored - i.e., tested for their uniformity, and all obstruction cleared off; and the interior surface must be smoothly parged at pargeted, or covered with mortar mixed with cowdung, to prevent cracking; or the inside flue-faces may be built in smooth regular bricks, and neatly flush-pointed in cement mortar - a process which has an advantage over pargeting in that there is no coating to kno happen when alterations have to be made The partition-walls between flues are cs of course, they should be bonded each wa the outside casing. Fig. 181 represents bond, 1/2-brick thick, and fig. 182 those in Flemish bond, while fig. 183 shows that there is practically little difficulty in bonding the withes into 9-inch outside walls of whatever bond; fig. 182a showing a much-used arrangement which has its advantages, although not strictly Flemish bond.
Fig. 178. Plan at AB.
Fig. 174. Plan at CD.
Fig. I75. Plan at EF.
Fig. 176. Plan at GH.
Plan at IJ.
Plan at KL Fig. 178.
Enlarged Section at CD. Fig.172.
The caps of chimney stacks are made more or less ornamental by the use of moulded bricks or terra-cotta, but more commonly by means of several oversailing courses, projecting or corbelling out one above another, as shown in fig. 184, and mitring at the angles, or returning all round the chimney, and finished off with a chimney pot. The top courses should always be set in cement; and it should be here remarked that no corbel or oversaving brick should project more than 2 1/4 inches at a time, just as offsets and all projecting bricks should be headers.
Hoop-iron bond, which has superseded the use of longitudinal bond-timbers, consists of thin long strips of wrought-iron, about 1 1/8 inches by 1/16 inchlaidand built in along the walls, between the courses, in rows at every two or three feet in height above head, and below sills of window, and turned at the ends up joints to assist in preventing rupture of the brickwork horizontally from unequal settlements. It is often specified to be tarred and sanded before being built in.
Wood bricks are often built in jambs for fixing joinery work to; though they are now generally superseded by breeze and patent bricks, which are fireproof. Elm pads, 4 1/2 inches by 9 inches by \ inch, are also used for the same purpose, and built in the joints, sometimes vertically, for the attachment of skirtings, etc.
Brick corbelling is a series of projecting bricks, for the purpose of giving additional suppor to, or to carry, wall-plates and other projections over plain walls below. Vide fig. 185.