COPINGS. 



122 



COPINGS. 



of the denser and colder current to supply 

 its place produces a current which destroys 

 the forcing power of the wall. 



Throating of Copings. Coping should 

 be always " throated " when made of stone 

 or slate ; with tiles it is neither possible 

 nor necessary to do this. By " throating " 

 is meant a narrow groove or channel cut 

 in the coping as close to the edge as 

 possible on the lower side, to prevent the 

 water from making its way back against 

 the face of the wall. When the inner 

 face, or one face only, of the wall is used 

 for training trees, the coping may be so 

 put on as to slant in the direction of the 

 face against which no trees are nailed. By 

 this means the water is thrown entirely to 

 the side of the wall that is not stocked with 

 trees. When a stone coping is put on in 

 this way, the higher edge of the coping 

 should be throated ; there is no necessity 

 for treating the edge on the lower side in 

 this manner. York paving, six inches 

 thick, Caithness flag, Ackworth paving 

 stone, and various heads of slate of the 

 Pembrokeshire and other Welsh counties, 

 make excellent coping stone. Roman 

 cement has been tried ; asphalt has also 

 been tried successfully. Glass, six inches 

 thick, and bevelled, has been thought the 

 best material for coping, being .perfectly 

 indestructible by the weather; and cast 

 iron has been found to answer. As to 

 shape, the flat coping, with a groove to 

 carry off the water, is considered to be 

 excellent. A very good coping is some- 

 times formed of brick and cement, in the 

 style of Fig. 2. Another form of coping 

 strongly recommended are stones, sloping 

 on each side, laid on flat ones placed 

 horizontally along the top of the wall. 



Temporary Copings. Admitting that a 

 coping projecting to the extent of two 

 inches is necessary for the protection of 

 the wall, and beneficial to the tree, the 

 best horticulturists come to the conclusion 



that temporary copings, extending eighteen 

 inches beyond the wall, as shown in Figs. 

 4 and 5, with protecting curtains depend- 

 ing from them, are very useful during the 

 spring months ; and Mr. Errington con- 



FIG. 4. TEMPORARY COMA'G FLAT. 



siders that by using them in autumn a 

 fortnight is added to the summer, and 

 time given for the ripening of the young 

 wood. He recommends a temporary 

 coping, seven or eight inches, in the 

 summer and autumn, and twice that in 

 April and May. Mr. Mclntosh considers 

 wet walls in summer as robbers of heat, 

 and that a wall with good projecting 

 coping, capable of being moved in the 

 heat of the day, is invaluable after sunset. 

 The portable coping at Dalkeith is a 

 boarding nine inches wide, supported on 

 iron brackets secured by bolts and nuts 



FIG. 5. TEMPORARY COl'ING INCLINED. 



passing through the wall. The boards are 

 attached to the brackets by screws. In 

 the coping shown in Fig. 5, the iron 

 brackets are constructed in the form of 

 a triangle instead of in the ordinary way, 

 as in Fig. 4 ; but they are secured to the 

 wall in the same manner. This construe- 



