316 ON THE CULTIVATION OF TREES. 



shorn of their fleeces in the spring ? the bark of the tree 

 is no less useful in the arts than the fleece of wool : you 

 recollect that it contains the astringent principle called 

 tannin, so essential in the preparation of leather : it is oak 

 bark which is principally used for this purpose, as it con- 

 tains the greatest quantity of tannin. 



Let us now consider the cultivation of single trees. 



Emily. Such as form the ornament of parks and pleas- 

 ure grounds ; and those which, dispersed throughout the 

 country, produce such beautiful scenery in England. 



Mrs. B. There is certainly no country which can 

 boast such a natural, and picturesque arrangement of trees. 

 On the Continent, single trees are generally planted in 

 rows : in some districts they may be considered as a sup- 

 plement to forests. Almost all the trees in Belgium, for 

 instance, grow in hedge-rows, or in avenues on the side 

 of high roads. What species of trees should you think 

 best calculated for the latter purpose ? 



Caroline. Evergreens would not be suitable ; at least 

 in our northern climates, because the road requires ex- 

 posure to the sun and wind during winter, and the pas- 

 senger requires no shade in that season. 



Emily. They should be trees which afford sufficient 

 shade in the summer, but whose foliage is not so thick as 

 to prevent the road from drying, after heavy showers. 



Mrs. B. For this reason the horse-chesnut is not 

 adapted to such a situation ; for, though it would afford " 

 excellent shelter to passengers during a shower, it would 

 render the road damp. Trees with very wide-spreading 

 roots are also objectionable, as they encroach on the ad- 

 jacent culture : on this account the acacia is excluded. 



Emily. But in England the road is almost always sep- 

 arated from the contiguous fields by a ditch, so that the 

 roots could not well interfere with their produce. 



Mrs. B. The roads in England are seldom bordered 

 with trees, except occasionally in hedge-rows : our climate 

 being too damp to admit of such an ornament, while in 

 the southern parts of the Continent trees are almost a 



1707. What comparison does Mrs. B. make between this practice and 

 the shearing of sheep! 1708. On the continent of Europe how are 

 single trees planted! 1709. Why would not evergreens be suitable 

 for this purpose! 1710. And horse-chesnut! 1711. And trees 

 with wide spreading branches! 1712 In England why are not roads 

 bordered with trees! 



