fame Strata in Ireland and Scotland. 
breadth ; but at about an hundred and fifty yards from the 
entrance, all its dimenfions are contracted, and it becomes fo 
finall as barely to admit further progrefs without crawling on 
hands and knees. There are fome calcareous flalaCtites pen- 
dent from the roof ; and in this cave, as well as thofe before 
mentioned,, wherever the water pervades through the joints of 
the chert, it tinges the fides of a ferruginous hue. 
From hence I returned by the fame route to the boat and to 
Freeport ; and having given you an account of the principal 
Whyn Dykes which I examined on the fea coaft, I will pro- 
ceed to relate thofe obfervations which occurred in my proorefs 
through the interior parts of the ifland, confining my remarks 
more particularly to the Whyn Dykes which conftitute the 
fubjeCt of prefent confideration. 
Afcending the hill from Freeport, in the way to Shinegarr. 
the road goes for about a mile over chert. Near Perfabus are 
beds of Hone marl, and a very large Whyn Dyke, rano-- 
mg N.E. and S.W. Hence the path leads over hornftone ; 
and in one part is a laminated hornftone, ranging E. and W. 
It inclines to a Ihiftus ; but where it Hands bare at day, is foft 
and partly decompofed ; but probably might be found ufeful 
for coverings, if it was tried in depth. Again the chert is 
feen, and again hornftone, in Which is included the lead vein 
of Shinegart, fituated on the S.E. fide of Portnealin Loch. 
Tins vein had been formerly worked ; but, when the old work- 
ings were cleared out, was found not worth purfuing. The 
vein ranges N.N.E. and S.S.W., is two feet wide, and hades, 
to the eaftward, and is crofled at right angles (a few yards to 
the northward of the workings) by a fmall Whyn Dyke. At 
Mullrees are old workings on a lead vein, which is about four 
feet wide, but left poor, and ranges N. and S. between lime- 
ftoil£ 
