WALLS AND TRELLISES. 161 



tion of the grape, this has been attended with the 

 best effects. But, unless when trees are young, the 

 wall ought to be covered with foliage during the sum- 

 mer, and the blackened surface would scarcely act, 

 and in the spring the expansion of the flowers would 

 be hastened by it, which is no advantage in cold, late 

 springs, because of the greater liability of early 

 flowers to perish, from cold. That a blackened surface 

 does produce a beneficial effect upon trees trained 

 over it is, however, probable, although not by 

 hastening the maturation of the fruit ; it is by raising 

 the temperature of the wall in autumn, when the 

 leaves are falling, and the darkened surface becomes 

 uncovered, that the advantages are perceived by a 

 better completion of the process of growth, the result 

 of which is the ripening the wood. This is indeed 

 the view taken of it by Mr. Harrison, who found the 

 practice necessary, in order to obtain crops of pears 

 in late seasons at Wortley, in Yorkshire (see ' Hort. 

 Trans.' III. 330 and VI. 453.) It hardly need be 

 added that the effect of blackening will be in propor- 

 tion to the thinness of the training and vice versa." 

 Lindley. 



The articles referred to by Lindley, being short 

 and practical, it may be well to transcribe them. 

 Henry Dawes writes thus to Sir Joseph Banks : "I 

 take the liberty of communicating to you my remarks 



