28 FRUIT AND KITCHEN GARDEN. 
duced. It is presumed that all the walls are to be covered, 
both within and without, with trees trained en espalier. 
Different portions of the inclosure wall are always built 
of different heights, and this variation of height is the 
more necessary when the ground approaches toalevel. In 
such a situation, and when the inclosure does not exceed 
two acres, the north wall may rise to the elevation of 14 
feet; the walls on the east and west may be two feet lower, 
and the south wall need not exceed 10 feet. In larger 
gardens, the walls are generally made proportionally higher : 
on the north, perhaps, 16 feet, on the east and west 14, 
and on the south 12. In several excellent Scottish gar- 
dens, planned by the late Mr. Hay, such as that at Castle 
Semple, a piece of building is made to project diagonally 
outwards from the corners where the walls meet at right 
angles. This projection is 16 or 17 feet in length. It 
serves to strengthen the fabric, and at the same time, acts 
as a brise-vent, breaking the force of the winds which sweep 
around walled gardens. : 
Walls inclined to the horizon have been recommended 
by Desaguliers, Hoffels, and others; but, independently 
of the theoretical objections which might be urged against 
them, and which, in actual practice, would probably coun- 
terbalance their supposed advantages, they must be incon- 
venient from their bulk, or the large space which they oc- 
cupy; and hence they have never come into general use. 
Where, however, the natural slope of the ground is too 
great for carrying on the ordinary operations of gardening, 
sloping terraces may advantageously be converted into a 
kind of inclined wall, to be faced with slate or some other 
material that does not readily absorb moisture. 
Bricks afford the best and the most kindly material for 
garden-walls. Being rough and porous they absorb radiant 
