‘ 
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na 
matic conditions are brought about on the two hemispheres; 
that, when the winters are in perihelion, the melting of the 
snow and ice and the increase of the Gulf-stream and other 
northward-flowing currents are as necessary a result as were 
the formation of the snow and ice and the decrease of the Gulf 
stream and those currents when the winters were in aphelion. 
And if this holds true in reference to recent and postglacial 
imes, when the eccentricity was small, it must, for reasons — 
which will presently be stated, hold true in a higher degree in 
reference to the glacial epoch, when the eccentricity was more — 
than three times its present-value. 
Melting of the Ice.—-When the winter solstice is in aphelion It 
sets in operation, according to theory, as has been shown,4 — 
action of the physical agents, 
one another. ‘The effect of this mutual reaction is very 
winters are in aphelion, but their efficiency in bringing about: 
this result is actually strengthened by their mutual reactions — 
on one another. ‘To illustiate this effect I quote the following 
i : aoa 
from a former article: Be, 
‘To begin with, we have a high state of eccentricity. This — 
leads to long and cold winters. The cold leads to snow, and - 
