290 Dr Ilibbert's Observations on Vitrified Fo?is. 



fusion of the stony materials has ever taken place. These cir- 

 cumstances, then, are fatal to the notion that vitrification was 

 the effect of design ; they rather show that it was merely in- 

 cidental to some other view, which the authors of it must have 

 contemplated. 



This theory is again as ill supported in its details. Mr Wil- 

 liams has supposed that the builders of these forts raised two 

 mounds parallel to, or in the direction of their intended wall, 

 and that they filled the ground formed by these parallel mounds 

 with fuel, above which they laid the materials intended to be 

 vitrified. Now this supposition is faulty, inasmuch as it proceeds 

 upon an incorrect view which has been taken of the actual con- 

 struction of these forts. A wall formed in such a manner 

 would present to view a pile of stony materials, with sides which 

 would be vertical, or at least nearly so ; and it would inclose 

 the summit of a hill after the manner of a modern park wall. 

 But this is not the character of a vitrified fort. The structure 

 of the least dilapidated example is much more rude, being rather 

 after the model of a filled up or extinct volcanic crater. Upon 

 the summit of an insulated hill, an incredible accumulation of 

 loose stones has been made to rise to the greatest height around 

 its circumference, and to gradually thin off towards the centre 

 of the enclosed site. An ori- 

 ginal form of this kind could 

 not then have been derived 

 from any parallel mounds. 

 This is evident from the an- 

 nexed imaginary section. 



These are the chief reasons which induce me to regard the 

 theory of Williams as perfectly utenable. 



3dly, The theory of Dr Anderson, that vitrification was pro- 

 moted by the employment of a peculiar vitrescible ore. 



The theory of Williams, during the same year in which it 

 was divulged, met with some qualified support from Dr An- 

 derson, in the dissertation by him to which I have already al- 

 luded. He observed of the walls of Knockfarril, that "they con- 

 sisted of stones piled rudely upon one another, and firmly ce- 

 mented together by a matter that had been vitrified by means 

 of fire, which formed a kind of artificial rock that resisted 



