OF CORNWALL. 107 
fea-ftiore ; nay, fome of thefe inland pebbles are fometimes large 
from ten to twenty inches, and fome three and four feet diameter. 
The queftion therefore is, Whence this fimilarity of fhape? Flow 
come the inland pebbles to be of that fhape, which, in fuch nu- 
merous inftances as the fea-fhore and rivers afford us, is manifeftly 
owing only to the agitation of fea and river-waters. Dr. Wood- 
ward (who left few parts of Natural Hiftory unattempted, and 
many particulars very fuccefsfully explained) labours hard to prove, 
that the inland pebbles are indebted to the departing waters of the 
Deluge for their roundnefs ; and that thefe waters had the fame ef- 
fect upon them as the fea upon thole of the fhores : but it is very 
juftly replied to this opinion, that the departing waters o: the deluge 
had neither time nor fufficient force in general, nor violence of 
agitation enough in all iituations to produce the effedt in queftion ; 
the caufe therefore afligned is not equal to the eftedt, and all the 
phenomena in pebbles produced by him u , may be rationally ac- 
counted for upon much lets difputable principles w . The truth is, 
this pebbly form is either natural or adventitious ; where the form 
is adventitious, it is owing either to the force of lea or river- waters ; 
on the fea and river-beach tbofe pebbles of the fofter kinds, and 
thofe which appear to have been fragments of the adjoining rocks 
(cr nodules which never arrive to the flze of rocks) owe their 
roundnefs to the neighbouring waves ; at the fame time it muff 
be confefled, that many which are on the fhore, as well as moft of 
the inland pebbles, are really found in their own original, and natural 
form in which they ftrft concreted. Natural pebbles may be fafely 
diilinguifhed from fadlitious : firft, by their having a coat or fhell 
moftiy of an even thick nefs, but of a different colour from the 
inward fubftance of the ftone : fecondly, when the pebble has a 
nucleus in or near the center, round which the body of the pebble 
is formed in ftrata ; thirdly, when the fibres of the body fpring 
like rays from a central point ; fourthly, thofe pebbles, which have 
nodulous bunches or excrefeer.cies of equal hardnefs to the reft of 
the body, may be looked upon as in the fame ftate and figure which 
nature lert them in ; fifthly, if a pebble ferments with acids, it is 
not a natural one ( HilL page 406); but whether this criterion be 
conclufive may be queftioned ; for I cannot fee why ftones of a 
fparry bafe may not be formed into a pebbly figure by the fame 
“ Ibidem ut fupra £sf pn(ftm. 
The ftone which Dr. Woodward ( ibidem ut 
fupra, page 47,) lays fo much ftrefs upon, may 
be explained without having recourfe to the de- 
parting waters of the deluge. This ftone conftfts 
of feveral fmall pebbles cemented together into 
one nodule. No more need be faid, than that 
the ground and the charge might be liquefeent at the 
fame time ; and though by the attraction of hnu- 
lar parts die little pebbles were kept together in 
feparate mafles, and the cement, at the lame time 
that it furrounded them, repelled them to their 
own limits, yet being both fupple enough to con- 
form to die force of external bodies, they became 
comprefled and rounded, and formed one nodule 
under one convex furface. 
principle 
