1792. antiquities in Scotland. 213) 
“From. these circumstances it appears to me ex 
——t probable, that the Danes, from having 'séén,” 
in their inctirsions, some of the vitrified fot GOS 
Rave admired the invention, and wifhed to, imitate 
them. We may suppose they might have been able 
to learn in general that they consisted'of walls of 
stone, intermixed with dry clay in powder, which 
was afterwards converted into a vitrified mafs by sur- 
rounding the whole with a stack of wood, or ‘other 
eombustibles » and then setting it on fire. But having’ 
been ignorant of the necefsity of employing only that: 
particular firbstance already described, which, from 
its general appearance; might be, on some occasions,’ 
mistaken for a kind of clay, they have probably ta- 
ken some ordinary clay and employed that in its stead, 
But as ordinary clay is hardly at all vitrescibie, they 
have not been able to succeed in their attempt ; but, 
instead of that, the stones, by the great heat apphedto 
them, have been scorched in the manner they now ap- 
pear, and the clay between them has been burnt to athes.’ 
This so perfectly accounts for the peculiarity obser- 
vable in the ruined walls of this fortification, and it 
is so difficult to afsign any other reason for the singu- 
lar appearan ice of them, that I couid*not avoid throw- 
ing this probable conjecture to-direct towards sepsis 
researches. j 
Although it-is ouly ef late that. the real-nature of | 
these vitrified walls has beeniknown, it is long since 
the vitrified matter has been observed ; but it was al-~ 
ways supposed that these were thenatural production of 
volcanoes ; from whenc¢e it’was inferred that volcanoes; 
had’ been very common in Scotland, at some very dis~ 
‘tant’period, But if-no, better. proof can be, adduced 
a = 
‘ 
