243 
On a part of the moor high and dry, and far removed from 
any water, we observed a slit or opening in the heather, 
about a foot or two across, and two or three yards long. 
On tearing away the heather and superincumbent soil, the 
curious appearance of the limestone at once caught our 
attention. The specimen which I have the pleasure to 
present to you will explain this better than any descrip- 
tion.* Whether these furrows have been produced entirely 
by the action of water, and if so, during what time, — 
whether to count by years, by centuries, or by ages, — 
whether it has taken place altogether in their present 
position, and if so, how the water came there, — and why 
the action was circumscribed within such narrow limits, — 
are all questions more easily put than answered. It seems 
most likely that the water must have been greatly assisted 
in this action, by its having absorbed a large quantity of 
carbonic acid ; and I was interested to learn, on making 
some inquiry of the lead miners who live thereabouts, that 
at certain seasons of the year, or during particular changes 
of weather, a strong current of air or gas issues from some 
such holes ; in certain instances evidently carbonic acid, as 
they found, on approaching the jet with a lighted candle, 
it was instantly extinguished, or, as was expressed by them, 
went black out. 
Frequently in winter, the snow, though very deep all 
round, is almost suddenly melted on the spot immediately 
above these holes, by this current of vapour from below ; 
and, as a further proof that hollows, both such as this last 
described and the former ones, communicate with others of 
considerable size underground, I learnt that in heavy falls 
of rain, or at the breaking up of winter, when the hill 
streams come down in torrents, the water will, every now 
* A specimen of the stone was here shown, singularly furrowed in every 
direction. 
R 2 
