370 RAMBLES OF A GEOLOGIST. 



rampart by the beacon-fires and the alkali, that were pro- 

 duced, according to Pliny, by the fires and the soda of the 

 Phoenician merchants storm-bound on the sands of the river 

 Belus. But the state of civilization in Scotland at the time 

 is not such as to permit of the discovery being followed up 

 by similar results. The semi-savage guardians of the beacon 

 wonder at the accident, as they well may ; but those happy 

 accidents in which the higher order of discoveries originate 

 occur in only the ages of cultivated minds ; and so they do 

 not acquire from it the art of manufacturing glass. It could 

 not fail being perceived, however, by intellects at all human, 

 that the consolidation which the fires of one week, or month, 

 or year, as the case happened, had effected on one portion of 

 the wall, might be produced by the fires of another week, or 

 month, or year, on another portion of it ; that, in short, a 

 loose incoherent rampart, easy of demolition, might be con- 

 verted, through the newly-discovered process, into a rampart 

 as solid and indestructible as the rock on which it rested. 

 And so, in course of time, simply by shifting the beacon-fires, 

 and bringing them to bear in succession on every part of the 

 wall, Knock Farril, with many a similar eminence in the 

 country, comes to exhibit its completely vitrified fort where 

 there had been but a loosely-piled hill-fort before. It in no 

 degree militates against this compound theory, borrowed in 

 part from Williams and in part from Sir George, that there 

 are detached vitrified masses to be found on eminences evi- 

 dently never occupied by hill-forts ; or that there are hill- 

 forts on other eminences only partially fused, or hill-forts 

 on many of the less commanding sites that bear about them 

 no marks of fire at all. Nothing can be more probable than 

 that in the first class of cases we have eminences that had 

 been selected as beacon-stations, which had not previously 

 been occupied by hill-forts ; and in the last, eminences that 

 had been occupied by hill-forts which, from their want of 



