III. On the Granite Tors of Cornwall, 



By J. Mac Culloch, M.D. Chemist to the Ordnance, and Lecturer on' 

 Chemistry at the Royal Military Academy at Woolwich. 



X Have the honor of presenting to the Society three drawings 

 which I have selected from my portfolio, for the purpose of 

 illustrating the changes which the influence of time and weather- 

 produces on certain varieties of granite. The subjects are all 

 chosen among the granites of the west of England j and that I might 

 at the same time preserve memorials of circumstances which are 

 remarkable independently of their geological interest, I have taken, 

 two of my examples from places which have called forth more 

 admiration from the common spectator thari even from the phi» 

 losopher, and which form two points of attraction for the curious 

 or Idle who annually visit Cornwall. Not only indeed have idle 

 curiosity and ignorant speculation busied themselves in accounting 

 for phenomena which many of the vulgar have deemed little less 

 than miraculous, but learned antiquaries have tortured their iur 

 ventlons and have constructed religious systems for the purpose of 

 explaining these very simple and intelligible natural appearances, 

 by the rites of a mysterious and Druldlcal worship. I trust I shall 

 be pardoned, if while I deduce from these facts the geological 

 consequences which depend on them, I likewise give a more 

 particular detail of the appearances themselves which have excited 

 so much of the attentign of all visitors. 



