HISTORY of the SOCIETY. 9 
veins one connected and uninterrupted mafs, muft have flowed 
in a foft or liquid ftate into its prefent pofition. 
In giving an account of thefe obfervations, Sir JamEs Hat 
was led, by finding it impoflible for him to exprefs his ideas 
clearly on the’ fubjeét, to enter at confiderable length into a dif- 
cuffion of the terms of mineralogy, the imperfection of the 
language of that fcience, and the principles on which a lefs am- 
biguous nomenclature might be formed. He particularly 
pointed out, as the bafis of fuch a nomenclature, the grand di- 
vifion which nature has made in the mineral kingdom, into 
ftratified and unftratified bodies, the former comprehending 
both the primary and fecondary ftrata, the latter comprehend- 
ing granite, porphery, bafaltes, trap or whinftone, and lava. 
He next ftated the argument which the facts concerning 
granite that have been referred to above, afford in fupport of 
Dr Huttown’s Theory of the Earth. He remarked alfo the , 
great number of facts which he had met with in Scotland, and 
in the volcanic countries of Italy, that were connected and ex- 
plained by that theory, and by no other; concluding on the 
whole, that there was fcarcely any fyftem in phyfics eftablifhed 
on more folid principles, and that the publication of it was 
likely to form a very important epoch in the hiftory of this 
branch of philofophy. 
To atheory, however, which embraces fo great a variety of 
objects, fome difficulties muft be expected to occur; and this 
is the more likely to happen, that though the agents employed 
in it be fuch as we are well acquainted with, yet they are in- 
. troduced as acting in circumftances very different from thofe 
in which we ufually fee them act. 
Or thefe difficulties the moft confiderable appeared to Sir 
James Hatt to be the following: In granites which contain 
quartz and felt-fpar, it frequently occurs, that the felt-{par is feen 
with the form of its cryftals diftin@lly defined, whilft the 
quartz is a confufed and irregular mafs, being almoft univer-. 
Vou. IIL (B) fally 
