OF CORNWALL. gg 
building, is free in working, yet hard enough for every kind of hone- 
work in water as well as out, and much fuperiour to Portland for 
heps and water-works : it is alfo fent rough-hewn to Briftol in large 
dabs, which are there further polifhed for calling thin broad plates 
of copper. The pyramid in Arwinek grove at Falmouth, is folid, 
and built of this hone. It was erected by the late Martin Killigrevy 
of Arwinek, Efq; in the years 1737 and *73^ at the expence of 
455 Pounds, fourteen feet wide at the bottom, and forty feet high, 
each fide correfpondent in number and fize of hones to the front 
here exhibited, Plate XXIV. Fig. vii. the middle layed with roughly- 
fquared hones, and their interhices filled with liquid cement; fo that 
a more durable work can fcarcely be imagined ; and great pity it is, ' 
that it was not placed as confpicuous as its folidity deferves. Gen- 
tlemen face the fronts of their houfes with this hone to goodf effedt, 
as may be feen at Carclew, the feat of William Lemon, Efq; Plate XI. 
page 96, and other places. Of two fpecimens weighed in the hy- 
drohatic balance, one weighed to water as 2 - - £ to 1, the other 
weighed only as 2 - - ] Q to 1 n . There is a very good granite of the 
fame kind in Karn-mel-bal in St. Juh. 
In the parifh of Madern there is a very pretty moorhone, but 
rare; the ground milk-white, glofly quartz or coarfe cryhal, the 
charge confuting of large black fpots of cockle. Rochrock, in the 
parifh of Roch, differs only from this, that the charge is fmall black 
fpecks, from the tenth of an inch and under, very numerous, thickly 
and equally difperfed, fo as to be of a mottled colour : this hone is 
in large mafles. The tendereh and freeh kind of this hone, and 
neateh for moldings, is that of Tregonin, in the Parifh of Breag, of 
which is built the portico of Godolphin houfe, the feat of the Right 
Honourable the Earl of Godolphin, Plate XII. and the New Church 
at Helhon, the donation of the fame munificent Lord. The ground 
is of a white, opake grit, tender almoh as clay, interfperfed with 
granules of quartz, cinereous, tranfparent, laminated, fmall from 
the eighth of an inch and under. The hone is foft, and eafy for 
working, efpecially when firh raifed, but afterwards hard and lahing ; 
extreamly white when newly wrought, but apt to contract a mofiy 
green hue in time. It weighs to water as 2--^ to 1. Of all the 
granite kind in Cornwall, this, if I have been rightly informed by a 
gentleman 0 who has tried many experiments this way, is moh pro- 
per for making porcelain. 
In the parifh of Ludgvan p there is a fingular kind of granite ; Dove- 
1 coloured. 
n By which, as well as many other experiments, weight of any fort of {tone by experiments made 
it appears, that in parts of the very fame concrete upon any fpecimen. 
{tone the ground and charge are mixed in different 0 Mr. Cookworthy of Plymouth, 
proportions, and that there is no determining pre- ? Rcctius Ludvon. 
cifely, but only in general and at a medium, the 
the 
