198 



THE GAEDENEE'S ASSISTANT. 



English bond (fig. 257), consisting of alternate 

 courses of headers A A and stretchers b B; this 



Fig. 257.— English Bond. 



is the strongest form of bond, and does not 

 provoke scamping. 



Scotch bond, consisting of one course of headers 

 to every three, four, or five courses of stretchers. 



Fig. 258— Single Flemish Bond. 



Single Flemish bond (fig. 258), consisting of 

 header and stretcher alternately in each course 

 on one side of the wall, and of alternate 

 courses of headers and stretchers on the other 

 side; this bond necessitates a considerable 

 number of half-bricks or false headers, and is 

 deficient in strength. 



Double Flemish bond, consisting of header 

 and stretcher alternately in each course on 

 both sides of the wall; this also is a weak kind 

 of bond, being deficient in headers, and necessi- 

 tating a great proportion of half-bricks. 



A 9-inch wall can be rendered very secure by 

 piers 1 foot 10 h inches broad, and projecting 

 only 4 h inches from the wall. They should be 

 12 feet apart, and ought to be carried up to 

 within 2 or 2^ feet of the top of the wall, and 

 protected by a coping. 



Hollow Walls. — Fig. 259 shows plan and sec- 

 tion of an excellent form of hollow wall. It 

 will be observed that headers and stretchers 

 alternate, and that every fifth header on each 

 side of the wall is a whole brick, and that the 

 other headers are half -bricks. In the next 

 course a stretcher must be laid across the 

 header at s, and a full-length header from the 

 face of the wall at n. In the third course the 

 bricks should again be laid as in the first, or 

 as represented in the figure; the fourth like 



the second, the fifth like the first, and so on, 

 till within a few courses of the top, and these 

 should be solid, as represented in the section. 

 In this way, at intervals of about 30 inches, 

 there are 4j-inch partitions, which are solid, 

 except where the end of the header s may not 

 touch the opposite stretcher n. 



There are other modes of constructing hollow 

 14-inch Avails, and which are well known to 

 builders, but the} 7 are all, we consider, inferior 

 to the above. 



Concrete may be formed of clay burned into 

 ballast, gravel, stone, or furnace clinkers, and 

 by packing hard materials, such as brick burrs, 

 hard-burned lumps of clay, large stones, &c, 

 in the centre of the concrete, a considerable 

 economy of cement may be effected. In form- 

 ing the concrete, Portland cement in the pro- 

 portion of one of cement to seven of gravel or 

 ballast is employed. 



Copings. — Stone copings are perhaps the best, 

 but they are very expensive, and there are now 

 various cements which form excellent substi- 

 tutes, for instance Portland stone cement. Good 

 copings may also be made of glazed fire-brick, 

 terra-cotta, or composition stone. The coping 

 should be raised in the middle so as to allow 

 the wet to pass off, and it ought to project 

 2 or 2 J inches beyond the sur- 

 face of the wall on each side; a 

 groove or throating for the drip 

 should likewise be made in the 

 under side of the projection. 

 Copings are also made slanting 

 towards the back of the wall, 

 with a groove on the under side, 

 so as to throw the water off. In 

 each case the projection from 

 the face of the wall should not ex- 

 ceed that already stated. Some 

 recommend a much greater 

 width in order to prevent radia- 

 tion, and thus serve as a protec- 

 tion for the blossoms in spring. 

 But there are several objections 

 to wide permanent copings; 



M8a^^^^ 





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Fig. 259.— Plan and Section of Hollow Wall. 



they are very expensive, unsightly, and even if 

 ! they project 6 inches they would not answer so 

 ! well for protection in spring as a broader tern- 



