238 - Dr. Cooper on Volcanoes 
3. Sir H. Davy’s theory of the metallic oxyds (metals ? 
Ed.) of the earths, has been applied to volcanoes: they are 
supposed to become incandescent by decomposing water, or 
atmospheric air, and uniting to oxygen. 
his source of volcanic action must be renounced ; inas- 
much as the nucleus of the earth being more than 5 times 
heavier than water, cannot consist of substances that are as 
y 
cause operating at a remote period, and at present unknown 
to us: and that the nucleus has not yet had time to cool. 
I am aware of all Murray’s objections to this hypothesis, 
but I incline to it for the following reasons, viz: 
1. That there is in pointof fact, a source of heat below the 
old granite, sufficient for the fusion or ignition of the sub- 
stances ejected from volcanoes in the state of fusion or igni- 
tion in which we find them ; the great mass of which are the 
hornblende rocks, or primitive trap. Wherever we propose 
to get the fire for this purpose, there it is. 
2. That the late experiments on the temperature of mines 
in England, Germany, and France, shew that the warmth in- 
creases regularly as you descend, in the proportion of at least 
twelve degrees of Fahrenheit’s thermometer, in a thousand 
feet. I would not pretend from about twenty experiments, 
at various depths, in various mines, of various countries, 
that we have data enough to assign the ratio to the center 
of our globe; this would be presumptuous in the present 
imperfect state of our knowledge: still, these are the facts: 
there is no getting rid of them: they point directly to a grad- 
ual increase of heat in some ratio, and the general phenom- 
ena of volcanic action confirm it. 
‘Will this consideration account in any degree for the re- 
mains of animals of warm climates found in cold ones? 
