CONSTRUCTION OF GARDEN WALLS. 



79 



offices behind. The great objection to 

 9-inch walls is, that both sides cannot be 

 wrought fair — in other words, both sur- 

 faces will not be even. This arises from 

 difference in the length of the bricks ; 

 for although all are cast in the same 

 mould, yet, from some contracting more 

 than others during the process of drying 

 and burning, a difference of half an inch 

 often takes place in their length. This 

 might to a certain extent be remedied by 

 selecting those to be used as headers, 

 that is, those which are laid lengthways 

 across the wall ; the others, of greater or 

 less length, could be used as stretchers, or 

 such as are laid lengthways on the wall. 

 It may be argued that bats, or half or 

 broken bricks, might be used, as both 

 ends could be laid, so as to be fair on 

 both sides; but the bond or tying to- 

 gether of the wall, which is the real use 

 of the headers, would not be effected, and 

 consequently the strength of the wall 

 would be greatly lessened. 9-inch walls 

 are all very well when only one side is 

 to be wrought fair, as against banks, in 

 the case of ha-ha's, &c. 9-inch hollow 

 walls may be wrought fair on both sides, 

 but not with common bricks, as will be 

 noticed hereafter. 



It ought to be remarked here, that the 

 English brick is about 8| inches long, 

 though generally called 9 inches ; where- 

 as the Scottish brick is 10 inches long, 

 and hence such walls are in Scotland 

 called 10-inch walls. But since the duty 

 has been taken off bricks, they may be 

 made of any size ; and, consequently, the 

 thickness of walls ought not to be calcu- 

 lated by inches, but by bricks and half 

 bricks, according to their size. 



The solid brick and concrete wall, fig. 

 50. — This method of construction is often 

 adopted to economise bricks, and is as 

 follows: The sides are carried up brick 

 on bed, and, whatever thickness is in- 

 tended, the space between is filled up with 

 rough gravel, stone chips, broken brick- 

 bats, or any dry, hard material. As the 

 building goes on, thin hot lime grouting 

 is poured into the heart of the wall till all 

 the spaces between the packing are com- 

 pletely filled. This adheres to the side 

 brickwork, and cements the whole to- 

 gether into one solid mass. Some brick- 

 layers run in headers, or bricks laid 

 across the wall, with a view to tie the 



Fig. 50. 



sides together, at distances of a few feet 

 apart ; but this is quite unnecessary, the 

 strong adhesion of the grout- 

 ing to the inner sides of the 

 bricks being quite sufficient. 

 Where walls are put up to suit 

 temporary purposes, this plan 

 should not be adopted, as it is 

 almost impossible to separate 

 the bricks from each other after 

 the concrete has become fully 

 set. By this plan it will readily 

 be seen that a great saving of 

 bricks is effected. For exam- 

 ple, a 14-inch wall, built solid, 

 requires 3620 bricks per rod 

 English, whereas, by this plan, 

 1210 are sufficient, being the 

 number required to build two 

 if 4-inch walls only. If we add 

 t5z i 1 1 ' i a to this the expense of the con- 

 crete, we shall find that the brick and 

 concrete wall is much the cheapest and 

 most durable, both being of the same 

 thickness. 



The brick and stone wall. — This kind 

 of stone wall is often built in Scotland, 

 where stone is cheap, and bricks in gene- 

 ral expensive — the object being to save 

 the latter, and at the same time have all 

 the advantages of a brick wall on one 

 side, usually the south. The principal 

 part of the wall is built with stone and 

 faced with brick, on what is called brick- 

 on-bed fashion. This is in very few cases 

 a cheap wall, the extra labour on the 

 stone part raising its cost to that of a 

 brick wall throughout. 



Hollow brick walls. — Of these there 

 are now several kinds, all having peculiar 

 merits, the chief of which are, saving of 

 material, and rendering them at the same 

 time capable of being heated by smoke 

 and hot air, or hot water either in cast- 

 iron pipes or gutters. Hollow walls, in 

 consequence of a circulation of air con- 

 stantly going on through every part of 

 their interior, are much drier than 

 solid walls, and hence much warmer. 



The principal walls in the new gardens 

 at Dalkeith are hollow, 12 feet high, and 

 18 inches thick. They are constructed 

 as follows : — Upon a solid rubble stone 

 foundation, rising to within 6 inches of 

 the surface, nine courses of bricks are 

 laid on bed, and form the side of the 

 wall ; the tenth course on each side has 



