On blacking Garden Walls. 



453 



the trees, for it would close up the pores of the wood, and 

 consequently do injury. 



After the wall is coloured I allow the trees to remain loose 

 from the wall until the coal tar has set (unless strong winds 

 prevail, in which case I secure the main limbs and branches 

 to the wall), in order that the shoots may not be damaged by 

 coming in contact with it before it is dry. When the wall 

 has become moderately dry, I nail the trees to it. A wall of 

 sound bricks will not require recolouring more than once in 

 ten years. Coal tar being very cheap a wall of considerable 

 extent may be coloured for a trifling sum. Any dark coloured 

 paint will answer the same purpose, but is far more expensive, 

 and requires renewal more frequently. 



The dark colour absorbing the rays of the sun, the wall 

 acquires at least ten degrees of heat more than the walls not 

 coloured as directed : thus affording great assistance in matur- 

 ing the buds upon fruit-bearing shoots, so that the trees may 

 be productive. In cold and wet seasons, without such aid, I 

 should not have been able to obtain ripe buds upon fruit 

 trees under my care. This I have had ample proof of by the 

 unfruitfulness of those trees which are against walls not 

 coloured, at the same time that trees' against coloured walls 

 were abundantly fruitful. The wall being coloured is also a 

 preventive of insects harbouring in it and also tends to keep 

 it dry. 



The growth of young trees is much promoted by the colour- 

 ing and they are sooner brought to a supply of fruitful buds. 



I am, Sir, 

 Your very obedient Servant, 



Charles Harrison. 



