28 CONSTRUCTION OF 



their stems are hollow, and the material of which 

 they are composed, is so condensed on the surface as 

 to possess nearly the hardness of metal. Silex is 

 one of their component parts, and if two pieces of 

 hamboo are rubbed together, they emit a pale light. 

 Sir Humphry Davy first observed this phenomenon 

 while watching a young child who was playing with 

 some bonnet cane. He sought out the cause, and 

 on examining the epidermis, it was found to contain 

 the properties of silex. The epidermis of reeds and 

 corn, and grasses, is similarly endowed. The corn 

 and grasses contain potash, sufficient to form glass 

 with their flint, and if a wheat or barley straw, or 

 even a stalk of hay, be subjected to the action of 

 the blow-pipe, a perfect globule of hard glass may 

 be obtained. 



Thus while a simple grass is secreting a volatile 

 and evanescent perfume, it also secretes a substance 

 which is an ingredient in the primeval mountains of 

 the globe. 



Beautiful fern, 



Thy place is not where art exults to raise the tended flower, 

 By terraced walk, or decked parterre, or fenced and shel- 

 tered bower, 

 Nor where the straightly levelled walls of tangled boughs 



between, 



The sunbeam lights the velvet sward, and streams through 

 alleys green. 



Thy dwelling is the desert heath, the wood, the haunted dell, 

 And where the wild deer stoops to drink beside the mossy 



well ; 

 And by the lake with trembling stars bestud when earth is 



still, 

 And midnight's melancholy pomp is on the distant lull. 



