132 antiquities in Scotland. May 30. 
SE 
It appears by the section here given, that the wall 
all round js covered on the outside with a crust of 
about two feet in thicknefs, consisting of stones immer- 
sed among vitrified matter ; some of the stones being 
half fused themselves, where the heat has been great- 
est, and all of them having evidently suffered a con- 
siderable heat. This crust is of an equal thicknefs, 
of about two feet from top to bottom, so as to lie 
back upon, and be supported by, the loose stones be- 
hind it. 
Within that crust of vitrified matter is another: 
stratum of some thicknefs, running from top to bot- 
tom, exactly parallel to the former, which consists 
of loose stones that have been scorched by the fire, 
but discover no marks of fusion. The stones-that 
are nearest the vitrified part of the wall being most 
scorched, and those behind becoming gradually lefs 
and lefs so, till at length they seem not to have been 
affected by the heat in the smallest degree, I have 
endeavoured to represent this in the drawing by the 
gradual decrease in the fhading. 
