GENERAL CULTIVATION. 227 



would, in such cases, be a good proportion. The trees in the bays of 

 Buoh walls almost wholly escape winds, as the latter rush along in a 

 straight line across the convex line of curves. 



Another mode of compassing this permanent protection from winds 

 consists in the erection of panelled walla. These form excellent boundary 

 lines between small gardens, and are far more ornamental and but little 

 dearer than straight walls; for it is obvious that the extra bricks of 

 the projecting pillars may be safely taken out of the panels. With a 

 iMrojection of 4in. or 9in. at intervals of 8ft. or 10ft., the trees in 

 the panels are protected from the sweeping force of the wind rushing 

 along in the line with the wall, and it is such that do most harm in the 

 spring. 



But of course the majority of walls are straight, and for these it is an 

 easy matter to make and fix breaks, formed of wood, glass, canvas, and 

 mats, to throw the wind right over the wall, or sharply cut its currents 

 into such short lengths as to break its destructive force. These break- 

 winds should be from 2ft. to 30in. wide at their base, and may taper into 

 a breadth of from 6in. to 9in. at the top of the wall. Narrow walls, 

 9in. or 14in., are liot seIdom< built with such stays as buttresses, and 

 their protective power on the face of the wall is as apparent as it is 

 valuable. 



Other modes of protection consist in the application of permanent 

 coverings of semi-transparent textile fabrics, to remain on the walls 

 night and day, till all danger of frost is over ; and the use of thicker 

 materials, such as canvas, cloth of any kind, mats, wooden shutters, &c., 

 to be applied during frosty nights and removed by day. The first 

 materials are the best and most suitable for amateurs, few of whom 

 would be at the trouble needful to command success with movable 

 protection. Netting of all shapes and sizes of mesh and material is 

 perhaps the best of all the permanent protectors, suspended from the 

 top of a wide permanent or portable copjng, doubled or trebled, accord- 

 ing to the quality of the net and the size of its mesh, and carried down 

 to the ground, or nearly so, within 18in. or 2ft. of the trees ; such a. 

 screen almost baffles the energy of radiation. The heat removed from 

 the trees is arrested by the screen of netting, and most of it returned on 

 the principle of reciprocity that governs the laws of radiation. Thin 

 canvas is the next best permanent protector. Next to these come screens 

 of spruce and other boughs, fern fronds, dried asparagus tops, loose 

 straw, &c. All these fixed modes of protection have a compound action, 

 each of which is equally valuable, and the nett result of both is the pre- 

 serving the walls and the trees cooler by day and warmer at night. In , 

 a word, the one function saves the trees from' being desteoyed by the 



