WALLS, ESPALIER-RAILS, AND TRELLIS-WORK. 



141 



only necessary in the case of conservatory walls. Where no trees 

 are planted on the north side of an east and west wall, the coping is 

 sometimes bevelled, so as to throw the rain-water to the north side as 

 in fig. Ill ; but this can never be advisable when trees are trained 

 there. 



In the construction of walls they are generally built solid ; but 

 when the wall is formed entirely of brick, a saving of material is 

 obtained, as well as a warmer wall produced, by building them hollow. 

 There are various modes of effecting this, but one of the simplest is 

 that shown by the plan fig. 112, in which a wall fourteen inches wide, 



Fig. 112. 



with a vacuity of five inches 

 and a half, may be built ten 

 or twelve feet high with little 

 more than the materials requi- 

 site for a solid wall nine inches 

 wide. Such walls may be 

 carried to the height of ten or Plan of a hollow brick wall 14 inches wide 

 twelve feet without any piers, and 12 feet high. 



and one advantage attending them is that they can be built with a 

 smooth face on both sides, whereas a solid nine-inch wall can only be 

 worked fair on one side. A still more economical wall may be formed 

 by placing the bricks on edge, which will give a width of twelve 

 inches that may be carried to the height of ten feet without piers. 

 Walls of both kinds have been employed in the construction of cottage 

 buildings, as well as in gardens. (See ' Encyc. of Cottage Archi- 

 tecture,' where several kinds of hollow walls are described.) A very 

 strong wall, only seven and a half inches in thickness, may be formed 

 of bricks of the common size, and of bricks of the same length and 

 thickness, but of only half the width of the common bricks, by which 

 means the wall can be worked fair on both sides. The bricks are laid 

 side by side, as in fig. 113, in which a represents the first course, and 

 F 113 & the second 



course. The 

 bond, or ty- 

 ing together of 

 both sides of 

 the wall, is not 

 obtained by 



laying bricks across (technically, headers), but by the 

 full breadth bricks covering half the breadth of the 



Fig. 114. 



cxdt 



Plan of a brick wall 74 inches thick. 



broad bricks when laid over the narrow ones, as shown 



in the dissected horizontal section, fig. 113, at 6, and in 



the vertical section, fig. 114. Besides the advantage of 



being built fair on both sides, there being no headers, or 



through and through bricks, in these walls, when they 



are used as outside walls the rain is never conducted 



through the wall, and the inside of the wall is conse- 



quently drier than the inside of a wall nine inches in 



thickness. These walls are adapted for a variety of purposes in 



foi c ]c wall 



