304 



SCIENCE OF GARDENING. 



PART II. 



of coping. On the other hand, copings which have a considerable projection are 

 known to protect wall-trees from spring frosts. We prefer for this purpose moveable 

 copings. (1493.) 



1558. The brick and stone ivatt is a stone wall faced with four inches of brick-work, or 

 what is called brick and bed, on the side most exposed to the sun, as on the south sides 

 of east and west walls, and on the insides for the sake of appearance of the two end, or 

 north and south walls of enclosed gardens. Where free-working stone abounds on the 

 spot, such walls are erected at much less expense than walls entirely of brick. Whether 

 they are as dry, durable, and warm, depends on the sort of stone ; some schistous and 

 other argillaceous stones are apt to be damp, but compact limestones may be accounted 

 as good as brick, and if they are of a dark grey or blue color, better on account of their 

 absorption and refraction of heat. 



1559. The solid brick wall is the simplest of all garden-walls, and where the height 

 does not exceed 6 feet, 9 inches in thickness will suffice ; when above that to 13 feet, 

 14 inches, and when from 13 to 20 feet, 18 inches in width are requisite. In most 

 cases, such walls may be contracted in width as they are carried up, so that a 20 feet 

 wall may begin with 18, and terminate in 9 inches in breadth. The contraction must 

 be gradual from bottom to top ; or if accomplished by rebates, they must be bevelled, 

 by means of a course of sloping-edged or flanched bricks at each set off ; and these must 

 be made exactly alike on both sides of the wall, in order to preserve its centre of gravity 

 exactly in the centre of the foundation. 



1560. The flued wall, or hot-wall, (.figs. 236, & 237.) is generally built entirely of 

 brick, though where stone is abundant and more economical, the back or north side may 

 be of that material. A flued wall may be termed a hollow wall, in which the vacuity is 

 thrown into compartments (a, a, a, a), to facilitate the circulation of smoke and heat, 

 from the base or surface of the ground to within one or two feet of the coping. They 

 are generally arranged with hooks inserted under the coping, to admit of fastening some 

 description of protecting covers (1495.), and sometimes for temporary glass frames. 

 A length of 40 feet, and from 10 to 15 feet high, may be heated by one fire, the furnace 

 of which (6), being placed 1 or 2 feet below the surface of the ground, the first course 

 or flue (c) will commence 1 foot above it, and be 2 feet 6, or 3 feet high, and the 2d, 

 3d, and 4th courses (d, e,f), narrower as they ascend. The thickness of that side of the 

 flue, next the south or preferable side, should for the first course be 4 inches, or brick and 

 bed ; and for the other courses it were desirable to have bricks cast in a smaller mould ; 

 say for the second course 3, for the third 2|, and for the fourth, 2i inches in breadth. 

 This will give an opportunity of bevelling the wall, and the bricks being all of the same 

 thickness, though of different widths, the external appearance will be every where the same. 



236 



237 



Sometimes a vacuity is formed between the flue and the south or valuable side of the 

 wall (Hort. Trans, iv. 139.); but this, we think, maybe considered an extravagant 

 refinement. It cannot be carried into execution without employing a great quantity of 

 materials and much labor. A wooden or wire trellis is also occasionally placed before 

 flued walls ; but both modes suppose a degree of forcing which does not appear ad- 



