Book I. 



WALLS. 



471 



defoliated ; while in summer, the same border is shaded by the foliation of the trees, and 

 thereby as well adapted for salading and late crops, as the north border of any opaque 

 wall. This garden had round ends ; the semicircular compartments (f, g) formed by 

 which were devoted to fruit-shrubs ; and the other compartments (k), being rectangular, 

 to the culture of the ordinary annual crops : at one end was a building (A) serving 

 as a tool-house and watching-lodge. 



2468. Hot orflued walls have been in use in kitchen-gardens for more than a century ; 

 but till lately they were confined to walls with southern aspects. At present, however, 

 it is not uncommon, where all the four walls of a quadrangular kitchen-garden are of 

 brick, to flue the whole of them. The expense of a flued wall is exactly the same as that 

 of a solid one, what is lost in labor being gained in materials ; and it is found of great 

 advantage, in cold and late autumns, to apply fires for even two or three weeks, as well to 

 ripen the wood, as the remaining fruit. In spring also, such walls, either with or 

 without some of the different sorts of protecting covers (1492.) are found of great use 

 in forwarding vegetation, especially in all the northern counties of England, and in 

 Scotland. Flued walls are certainly not much recommended by Abercrombie, M'Phail, 

 Marshall, or Forsyth, probably from the climate in which these authors gained their ex- 

 perience not requiring such aids. It is acknowledged also, that " this species of forcing 

 is practised by many in a very injudicious way, and much mischief done through error to 

 thousands of fine trees." Nicol, however, the author of this remark, subjoins, that " flued 

 walls are certainly eminently useful, particularly in the northern parts of these kingdoms, 

 and are often necessary to the production of peaches and nectarines in bad seasons." 

 Switzer seems to have been the first to recommend them, giving various plans for hollow- 

 arched and flued walls in his Practical Fruit Gardener, some of which had been executed 

 and found to succeed in Lincolnshire, and at Buckingham House. Abercrombie says, M We 

 mention the hot wall without glass work, as among the projects for forcing, an old tried 

 one, but not to recommend it. The expense of glass work is saved by a false economy : 

 the plants are thus excited, on one side, by a strong artificial heat ; and exposed to frost 

 and damp violent winds, and heavy rains on the other. Many practical men have found 

 this contrivance calculated to produce an untimely show of blossoms, while the counter- 

 acting effect of their situation exposes both plant and blossom to perish. If not applied till 

 the decline of summer, it may do some good in assisting fruit to ripen." (Pr. Gar. p.596.) 



2469. Flued walls for the climate of Scotland are 

 highly approved of by Justice ; and, as they cost 

 no more in erection than solid walls, it may be ad- 

 visable in many cases to build them, whether steam 

 or smoke heat should be applied or not. The fa- 

 cility with which the former is applied to walls 

 through recent improvements (1561.) is certainly a 

 great argument in their favor. Our opinion is, 

 that in all complete gardens, the whole of the walls 

 should be flued or cellular (Jig. 238.), to admit of 

 the application of artificial heat at pleasure. One 

 boiler and furnace may easily be contrived to sup- 

 pi v heat to both the hot-houses and walls. 



2470. Cross walls (Jig. 427. a, b) are introduced 

 where the boundary wall is not sufficiently exten- 

 sive to produce the desired quantity of fruit, and 

 also to produce shelter to the garden. They are 

 very generally flued walls in all modern gardens 

 north of London, and are not unfrequently wholly 

 or in part covered with glass. The direction of 

 these walls is almost universally east and west, and 

 their height is determined by the surrounding walls 

 to which they are joined. These cross walls, Nicol 

 observes, are not placed nearer to each other than 

 one hundred feet ; if they be two hundred feet se- 

 parate, it is perhaps better. 



2471. Hedges are sometimes introduced instead 

 of cross walls; but it is obvious they possess only two 

 of their advantages, that of affording shelter and 

 shade. Where they are adopted for these purposes, 

 evergreens, as the holly, box, laurel, spruce, &c. 

 are to be preferred to deciduous trees ; as from their 

 surface being, at all seasons of the year, more com- 

 pact than that of deciduous hedges, they are less 

 liable to harbor birds and vermin. No hedge has 



H h 4 



