t 2 S3 3 
meets a proper Nidus of Wood, Reed, Grafs, or the 
like, it will forfake its State of Fluidity, and become 
a folid Stone : Why then fhould it feem more un- 
accountable or difficult, to conceive that the fame 
Alteration fhould happen in the Bowels of the Earth, 
and in larger Mafles of Matter? For as the fame 
Caufe will in like and equal Circumftances produce 
the fame Effect, fo to produce a greater Effedt [viz. 
an Alteration of Form or Motion in a greater Quan- 
tity of Materials), there is need only of a propor- 
tionably greater Force in the Caufe ; it being as eafy 
for a powerful Effort to produce a Rock, or a Moun- 
tain, as for a fmaller Force to congeal a Pebble, or 
form the fmalleft Gem. If it were poffible, there- 
fore, for us to be as attentive Witneffes of the 
Changes which happen under the Surface, as we 
are of thofe which appear on the Banks of every 
petrifying Spring, we fhould difeover many new 
Stones produced every now -and -then, which by 
their Firmnefs appear now to have been as old as 
the World (3). It is indeed a vulgar Miftakc to 
imagine, that Time has added, or fhall add, to the 
Firmnefs of a Spar ; or becaufe it is fo hard and 
compadt a Body, that it cannot therefore but be as 
old as the firft: Formation of Things 5 for Spar be- 
comes as hard at the firft Time of its confolidating, 
as it will be ever after, as we find by the exa<ft 
(3) Since the Writing of the following Treatife, Mr. 1 ii/l {Nat. 
Hijl. of Fojfih, p. 157.), by a curious chemical Inveftigation of the 
lapideous Contents of Water, fays, “ That Stones and Minerals, 
“ formed of Cryftal and Spar, need not be fuppofed all of them as 
£ ‘ old as the Creation or Deluge 3 but may be, and unqueftionably 
“ are, formed to this Day.” 
Shape, 
