Dr Hibberts Observations on Vitrified Forts. 285 



Art. XVII. — Observations on the Theories which have been 

 proposed to explain the Vitrified Forts of Scotland. By 

 S. Hibbert, M. D. F. R. S. Ed. &c. &c. (From the Ar- 

 chcBologia Scotica, vol. iv.) 



The members of this Society are no doubt familiar with what 

 is meant by a Vitrified Fort. By this term is implied an area 

 of ground, often of a round or elliptical form, and evidently 

 selected for some natural defence possessed by it, which is far- 

 ther protected by one or more inclosing ramparts, formed bv 

 stones ; these stones showing, to a greater or less extent, marks 

 of vitrification, by which they are cemented together. 



None of these vitrified forts exhibit, as from many writers 

 we should be erroneously led to suppose, any regular masonry 

 in their structure. Unhewn fragments of stones, and water- 

 worn boulders, sometimes mingled with smaller gravel, appear 

 in a quantity almost exceeding belief, following the contour of 

 the summit of a mountain, or, as in the instance of a fort which 

 is situated in the Kyles of Bute, following the contour of a 

 small holm or islet, elevated a few yards only above the level 

 of the sea ; and in cases where, owing to the more exposed 

 nature of the ground, a stronger defence is demanded, a dou- 

 ble or even treble rampart of the same rude materials is added. 

 The vitrification which characterizes these forts is, in some few 

 of them, displayed to an extent that is perfectly astonishing ; 

 while in other instances it is with difficulty to be detected. In 

 short, no two forts in their degree of vitrification are in any 

 respect conformable to each other ; and it is of importance to 

 add, that throughout Scotland numerous forts appear, only 

 differing from those which form the present object of inquiry 

 in the absence of all marks of vitrification whatever. 



These forts first met with scientific attention about hall a 

 century ago, when various theories were proposed to account 

 for the origin of their vitrification. At these I shall glance in 

 succession. 



1 Bt, The notion that the vitrification observable in these forts 

 ivus the result of volcanic agency. 



During the last century it was a very prevalent notion, that 



