38 ObservalijHs on the 



The sandstone is one of the most useful of all rocks, its re- 

 sistance to the wear of centuries, and to the dislocating agency 

 of tempests, is very visible in the durability of ancient fabrics, 

 and its perpetual integrity in mountains. Several castles on 

 the Wye, especially Goodrich, and the romantic abbey-ruin of 

 Tintern, have been composed of this stone. The particular va- 

 riety of it, which is most used in modern buildings, is the flag- 

 stone. With this too and the rough graniform pudding-stone, 

 the most analogous to granite, they form their cider mills, a 

 species of circular trough, in which the apples are compressed, 

 by what, to convey ideas of resemblance, may be called a stone 

 wheel. Iron enters very largely into its composition, and com- 

 municates that rusty hue, which, though it is sombre, and free 

 from obtrusive glare, can hardly be deemed beautiful, and is in- 

 consistent with the principles of modern taste, unless ameli- 

 orated with artificial plaistering. A considerable portion changes 

 its hue to green, but the red-coloured is predominant. The green 

 is not a distinct colour of a distinct rock, the same stone may 

 have both imparted. I am induced to think that this tinctis result- 

 ing from a chemical change : I have observed where water has 

 long remained on the surface of sandstone, and where light and 

 air have gained access, that a green, of the chloritic cast, has 

 appeared in circular discolorations ; it is probable then, that 

 some interchanges of action between oxygen and some other 

 united substance, perhaps sulphur, may have given origin to 

 this appearance*. We are to consider, however, as more strictly 

 geological, disposals which nature seems to have made of it. 

 In mountains it is arranged to their lowest depths, in immense 

 cubic masses, every way intersected by fissures, but as regu- 

 larly disposed as the dry walls of Cyclopian architecture. In 

 the vale its position is infinitely more irregular, scattered in 

 flat masses, and unconformable, giving irregularity to the 

 surface, and covered by a soil so homogeneous, as to display 

 to the weakest perceptions, its alluvial origin. This soil is al- 

 ways abounding in richness and fertility, and though its absorp- 

 tion of moisture is speedy, its retention is lasting. It is what 



* I am inforoietl by a vei7 intelligent character, that the greeu saud- 

 sioue stands lougcbt iu buildiug. 



