GARDEN STRUCTURES. 



197 



surface for training trees upon, these circum- 

 stances require to be considered in connection 

 with the question of height. With regard to 

 the first consideration, a wall 6 or 7 feet in 

 height will answer perfectly well. As to the 

 second condition, the higher the wall the 

 greater is the amount of sun-heat accumulated. 

 It is known that certain fruits that will not 

 ripen perfectly against a low wall will do so 

 upon a high one, and that, all things con- 

 sidered, the colder the climate, the higher the 

 walls should be. In the southern counties, 

 and in other warm situations, 10 feet may be 

 allowed for a south wall, but a height of 12 

 feet is better; and in the walls on the north 

 side, one side of which faces southwards, and 

 consequently presents the most favourable aspect 

 for the more delicate kinds of fruit-trees, 15 feet 

 or more in height would certainly prove very 

 advantageous. 



Thickness. — A wall of the standard thickness 

 of 14 inches is as substantial as need be desired 

 in gardens, and it may be carried up to a suffi- 

 cient height without the support of piers, pro- 

 vided the materials and workmanship are good. 

 The next less thickness of a brick wall, as 

 determined by the dimensions of a brick, is 

 9 inches; but to render a wall of this thickness 

 secure, if more than 8 feet high, it ought to 

 have piers. 



Foundations. — Garden walls have only their 

 own weight to support, and therefore do not 

 require to be so deeply founded as those of an 

 equal height in buildings 

 where there is the additional 

 weight of floors and roof to 

 bear; but the foundations 

 ought to be 3 feet deep, in 

 order that they may not be 

 loosened in trenching the 

 ground, as well as to prevent 

 the roots of trees from get- 

 ting underneath them. The 

 bottom of the trench for the 

 foundation should be exa- 

 mined, and if parts are found of a softer nature 

 than others, the bottom should be deepened 

 and made up with concrete or other materials. 

 Compact loam will bear a great weight without 

 yielding, so long as it is dry or nearly so; but 

 when wet it squeezes outwards under pressure, 

 and the wall sinks by its own weight. If this 

 took place equally along the whole extent of the 

 wall, as would be the case if the stratum of loam 

 were uniform, it would be of little consequence ; 

 but if part of the foundation is on loam and 



j part on gravel, a rent or shake is likely to take 

 j place. The base ought to be twice the thick- 

 ness of the wall, whatever that may be, and the 

 width should be diminished, as in fig. 256, by 

 equal steps on both sides, each step being not 

 more than c 2\ inches wide. 



Solidity. — A brick wall 14 inches thick is 

 unobjectionable; but hollow walls of the same 

 thickness answer exceedingly well, for they can 

 be made so as to present exactly the same ap- 

 pearance, and they are both dry and strong. 

 In a wall 100 feet in length, and 10 feet high 

 above ground, the number of bricks required 

 for 1000 square feet of wall surface would be, 

 for a 



14-inch solid wall, about 16,000 



14-inch hollow wall, about 12,800 



9-inch solid wall, with piers, about 11,060 



It will be seen from the above that, as com- 

 pared with a solid 14-inch wall, there is a con- 

 siderable saving of bricks in a 14-inch hollow 

 wall, but between this and a solid 9-inch wall 

 with piers the difference is not much, being 

 only about 1740 bricks. The piers, if they pro- 

 ject much, are unsightly, as well as obstructive 

 in training; and the shoots of fruit-trees thrive 

 best against a plane surface unshaded by piers. 

 These, therefore, ought to be placed on that 

 side which presents the least favourable aspect 

 for fruit-trees. 



Construction. — Although this can only be done 

 by practical masons and bricklayers, yet a 

 gardener ought to know something of the prin- 

 ciples, otherwise he would be apt to commit 

 errors in cases where he might have to propose 

 plans or give directions. 



Stone walls upon which plants are to be 

 trained should not be built of large blocks: if 

 the stones were dressed so as to make each 

 course 6 inches, that is, equal to two courses of 

 bricks, training could be very well performed 

 without a trellis, which a greater distance 

 between the courses would render neces- 

 sary. 



The usual size of bricks is nearly 9 inches in 

 length, 4^ inches in breadth, and 2h inches in 

 thickness. In good work, each course is exactly 

 3 inches deep. The arrangement of the bricks 

 should be such as to form a bond, that is, the 

 joints of one course should be overlaid by the 

 bricks of the one next above it, so that no two 

 joints of any course shall be in the same line 

 with a joint of the next course above it. There 

 are several varieties of bond, of which the 

 principal are : — 



