Dr Hibbert's Observations on Vitrified Forts. 289 



Nor could I in any of them discover a stone, large or small, 

 not affected by the fire, and in some measure vitrified.'" 



In connection with this theory, Mr Williams defines the 

 walls of a vitrified fort, when complete, after the following 

 manner: — " The walls are vitrified or run and compacted to- 

 gether by the force of fire, and that so thoroughly, that most 

 of the stones are melted down, and any part of them not quite 

 run to glass is entirely enveloped in the vitreous matter ; some- 

 times also they appear like vast masses of coarse glass or slag." 



But we shall now examine, with some degree of attention, 

 the validity of this theory, particularly as it has recently met 

 with a defence from a writer of no small eminence, who pos- 

 sesses a store of antiquarian and mineralogical knowledge, which 

 eminently qualifies him to enter the lists in the determination 

 of this question. I allude to a memoir published in the Tran- 

 sactions of the Geological Society of London, by Dr Maccul- 

 loch, and to his views on the subject which are contained in 

 his description of the Highlands and Western Isles of Scot- 

 land. 



The drift of the theory in question is, — that with the de- 

 sign of strengthening the walls of a fort, the stones have been 

 cemented by a regular process of vitrification. 



In support of this view Mr Williams has stated, that in none 

 of the vitrified forts which he examined could he discover a 

 stone, large or small, unaffected by the fire, or which was not 

 in some measure vitrified. This assertion, if correct, would 

 certainly go a great way to urge conviction, that the vitrifica- 

 tion of these forts was not an accidental or adventitious, but a 

 designed process. Never was there, however, a more unfound- 

 ed statement. At Dun Evan, where there is an extensive for- 

 tified site, the vitrification so far from having acted upon every 

 stone, is only to be detected in a space the dimensions of which 

 do not exceed two or three yards. I can also avow, without 

 dread of contradiction, that in numerous other sites the vitri- 

 fication is only to be found in small patches, or that extensive 

 portions of the ramparts which have composed their defence 

 do not show in the slightest degree the effects of fire. Nay, 

 even in the forts which display the greatest extent of vitrifica- 

 tion, considerable intervals may be readily traced where no 



