8 Proceedings of the Royal Physical Society. 
apparent. But these phenomena are seldom seen, except 
when found by those desirous to support their Plutonic views, 
a race of philosophers by no means rare, and who, I am 
sorry to say, are now occupying the highest places in the 
science. Formerly these gentlemen asserted that the gra- 
nite crystallised by slow cooling ; now it is found that this 
doctrine is untenable, and it must have crystallised by rapid 
cooling. If this latter view is correct, I ask the supporters 
of the hypothesis how they explain the fact that the lowest 
granite differs in no mineralogical character from the upper- 
most peak of the Himalaya mountains ? Surely the lowest 
portions of those great ribs on which the foundations of our 
fair earth were built must have been more highly molten, 
being so much nearer to their favourite central heat than 
the upper ranges, and therefore more slowly cooled. By 
the first view (that is Hutton and Hall's), the lower layer 
of granite should be more crystalline than the upper, hut it 
is not so. By the more recent theories of Harcourt and 
others, the upper layer ought to be the more crystalline ; 
hut it is not so, — and on the horns of this dilemma I leave 
the supporters of Hall, Hutton, and Harcourt. 
The last two dogmas of the new school of geologists are 
contained in the following words, which I quote from the 
Eev. Vernon Harcourt's report: — 
Is^, " All the consolidated strata, viewed chemically, bear 
marks of subjection to an action of heat agreeable to the 
theory of the earth's refrigeration in direct proportion to the 
age of their deposit ; and that they show that action most ex- 
plicitly in the presence throughout, but more abundantly as 
the series descends, of that peculiar form of silica which is che- 
mically reproduced by the action of heated volatile matter. 
2d, " That the igneous minerals were formed by molecular 
aggregation at a heat not exceeding perhaps that of an 
ordinary fire, either as a residuum from the expiration of 
fusible and volatile materials, or more generally as a deposit 
from volatile forms of matter." 
These seem very heavy dogmas to deal with ; but before 
accepting them, it is the duty of every mineralogist and 
geologist to test them before adoption as a part of their 
