en. i"^. 



MISCELLANEOUS. 



131 



an error. 



Eoots are obliged to keep the surface, because the food 

 of plants lies there, though many think that this food is 

 imbibed from the atmoshere ; if so, trees would not be 

 injured by having their roots covered. 



I believe Sir Humphry Davy first remarked, on the That^a hiii 

 assumption that the upward and downward growth of f^^t^f^^^^^ 

 plants IS vertical^ that woods and crops growing on the base wo\iid, 

 side of a hill would derive no greater advantage from 

 the additional space than if they grew on the horizontal 

 surface of its base. But it must be recollected, that, as 

 the plants on the side of a hill rise tier above tier, with 

 the same hght and aeration from above they have a 

 greater side light and aeration. They are, in fact, 

 placed head above head, like people in a race- stand, 

 where, but for this arrangement, the spectators would 

 have good opportunity for looking upward at the roof, 

 but none for looking sideways at the race. But the 

 merit of this principle is very apparent in the step-stands 

 in green-houses ; though, probably, the origin of these 

 stands may be the greater facihty they give to see and 

 to water the plants. But if the plants stood on the 

 area of the base of the stand, each would be shaded all 

 round by its neighbours, and would receive light only 

 from above. The base of what is called in Hampshire 

 ' a hanger,' or a hanging wood, would not support as 

 many trees with full heads as stand on the hill-side. 

 Let us conceive these 



Densas, umbrosa cacumiiia, fagos 

 to be sunk vertically downward from their beautiful 



k2 



