-mate, if it had any, was in opposition to that of the astronom- 
eal and physical agencies. It would prove a hindrance nota 
elp. 
Referring now to Mr. Wallace’s argument. When glacial 
conditions in the North Atlantic attained their maximum de- 
lion, and the physical causes to remain unchanged. It 18 
ussumed as possible that the astronomical conditions might be 
o 
a 
| 
et 
me 
oe} 
> 
— 
fe 
s 
= 
a 
ra) 
BD 
oe 
ag 
oO 
er 
oO 
ee 
Qu 
ct 
5 
| 
2) 
ard 
4 
=H 
° 
me 
n 
2) 
sss | 
° 
§ 
oD 
2 
jo] 
n v 
solstice being in aphelion during a high state of eccentricity, 2 — 
glacial condition of things is produced, will the fact of the — 
solstice-point being moved round to perihelion remove the gla- 4 
cial condition, if the physical causes remain unchanged m their 
mode of operation? My reply is, it certainly would not. Here — 
it is assumed that the physical causes are working in opposition 
to the astronomical; that when the solstice is in perihelion the — 
action of the physical causes, instead of being reversed, as It 
should be according to theory, still continues to produce and | 
maintain a glacial state of things, the same as it did when the — 
solstice-point was in aphelion ; and he asks, will the astronomical 
causes in this struggle manage to overpower the physical and 
produce a melting of the ice? I unhesitatingly reply, n0;,70° 
the physical causes are far more powerful than the astronomical, 
The astronomical causes, as we have seen, are perfectly unable — 
to produce a glacial state of things without the aid of the nie ‘ 
ical. How, then, could we expect that they could remove this 
glacial state if the physical causes were actually working” 
against them. ee 
In thus setting the physical causes against the astronomical, 
Mr. Wallace is basing his argument for the non-disappearayy” 
of the snow and ice on a state of things which cannot possibly 
under the circumstances exist. His question, to have cons®™ 
