Some of the principles involved in the effect of bonding on the strength of a wall, have already been discussed under "Stone Masonry." The other consideration is that of architectural appearance. The common method of bonding (Fig. 35) is to lay five or six courses of brick entirely as stretchers, then a course of brick will be laid entirely as headers. There is probably some economy in the work required of a bricklayer in following this policy. The so-called English Bond (Fig. 36) consists of alternate courses of headers and stretchers. If the face bricks are of better quality than those used in the backing of the wall, this system means that one-half the face area of the wall consists of headers; which is certainly not an economical way of using the facing brick. The Flemish Bond (Fig. 37) employs alternate headers and stretchers in each course, and also disposes of the vertical joints so that there is a definite pattern in the joints, which has a pleasing architectural effect.