Nm 
W. Hopkins on Changes of Climate. 335 
its surface had commenced. Undoubtedly this cause may be ap 
pealed to as sufficient for the production of almost any amount of 
terrestrial temperature ; but, if the temperatures thus to be ac- 
counted for be many degrees above the existing temperatures, we 
can account for them by this theory only with reference to peri- 
ods of very remote geological antiquity. I have also shown that 
any sensible effects of a difference of intensity in stellar radiation 
can be referred only to similarly remote epochs, and even for 
those periods the theory founded upon this notion appears to me 
vague and unsatisfactory. 
lat radiation. This cause, once admitted, might undoubtedly be 
deemed adequate to account for all the changes in question, nor 
oes there appear to be any well-defined d-priori objection to it. 
class of allied, but independent phenomena. The reception of 
such a theory must always be accompanied with great reserve, 
and must depend less on its own positive claims, than on an equal 
% greater want of such claims on the part of rival theories. 
The theory which attributes the changes of terrestrial temper- 
“old is by local elevation. If we attribute the former presumed 
Cold of western Europe to this cause alone, it would be necessary 
®T have shown ($ 24, p. 253), to elevate the whole region into a 
Vast Mountain-range, attaining in some parts the height of 10,000 
leet or upwards. But all geological experience assures us that 
ouch mountain-range exists without numerous dislocations and 
ether phen the 
Phenomena of elevation having determinate relations to 
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