OF CORNWALL. 93 
viz. a very fmall proportion of ftony cement added to a fine fand 
and earth. This ftone is confequently of a fmall grit, is very eafy 
to fquare, and makes very dry walls and dole joints, but feldom 
rifes larger than from a foot high to two feet long, and is apt to 
lcale off at the corners. Of this kind, but of a more compact, 
uniform, and finer grit, we find in fome places very good whet- 
ftones for edging knives and other tools : the rock, called Karn- 
Jenny, near Penzance pier, produces a courfe of thefe almoft as 
fair and good as the hones of the fhop, and are ufed as fuch in that 
neighbourhood. A fpecimen of this kind weighs to water as 
2 — to I, 
Some of the cinereous killas confift of thin lamina laid in ftreight 
lines one over another in like manner as flat, to which it approaches 
very near, but never rifes wide and thin enough to anfwer the ufes 
of it. Its maffes however are larger than thofe of the Helfton 
quarry, but more fpungy, fubjed to foft places, and more apt to 
decay and give way to the weather. Of this ftone is built the 
houfe at Nanfwhydn, Plate VIII. . 
In many places the quarry-ftone of the brown ferruginous killas 
rifes large and hard, and with this they build in the Weftern parts 
of Cornwall, and in the Eaft at Camelford, Lancefton, and elfe- 
where ; but it is fubjed to the fame inconveniency of damps as the 
yellow before-mentioned. In fome places it rifes in fuch large 
flakes, fo eafy for working, and they may be laid on their edge fo 
dole, that they prove excellent materials for building piers and 
moles into the fea ; the beft I have yet heard of, is that which rifes 
on the parfonage grounds of Mawnan, from which a great deal is 
carried off yearly for building and repairing the Kayes at Falmouth, 
St. Maws, and other trading towns in that harbour. 
On the South coaft, betwixt Lilkerd and the T&mar, there are sect.v. 
fome quarries of flat, which is brought down and flapped off at Slat. 
Tidiford and Morlham, and, by means of the Tamar, fupplies the 
neighbourhood of Plymouth with covering for their houfes, and is 
thence exported in pretty large quantities : there are alfo fome quar- 
ries of flat at Padftow on the North coaft, whence, for many miles 
to the Eaft, the whole country is fubjed to a ftielfy flat. There is 
a better quarry ftill at Tindagel ; but the beft covering flat which 
we have in Cornwall, and indeed in all England, “ perhaps the 
<( £neft in the world,” is at Denyball, about two miles South, or DennybaH 
Tindagel, which will therefore require our more particular notice. quarry 
The whole quarry is about 300 yards long and 100 wide: the 
deepeft 
* Dr. Woodward, Cat. vol. II. page 5. 
B b 
