(ilacial Xote.s from the Phmef Mars. — ('hajpoJi'. 97 
not yet at their maximum, for in the latter ease the Martian 
winter can exceed his summer by about 110 days. This would 
produce a winter of 398 and a summer of only 288 daj'^s. 
When we recall to mind the meteorological conditions of 
our own south polar regions it is scarcely possible to doubt 
that if eccentricity were the dominant factor in producing an 
ice-age there should be evidence of more extensive Antarctic 
snows on a planet possessing nearly the same inclination as 
the earth but an orbit six times as eccentric. On the earth S. 
Georgia, in latitude 55°, is covered with snow "many fath- 
oms deep at the sea-level and in the height of summer."'* 
Another fact deserves mention in this connection. Accord- 
ing to the " eccentricity theory" the north polar region of 
Mars should now be enjoying a warm interglacial climate. 
The inclination of his axis, which in amount is nearly equal 
to that of the axis of the earth, is such as to bring his north 
pole into the sunlight during the long aphelion passage of 
twelve months. Says Dr. CroU in "Climate and Time" (p. 
237) : "As the cold periods in the southern hemisphere become 
more and more severe, the ice would continue to advance 
northwards in the temperate regions ; but at that very same 
time the intervening warm periods in the northern hemisphere 
would become warmer and warmer and more equable, and the 
ice of the arctic regions would continue to disappear farther 
and farther to the north, till by the time that the ice had 
reached a maximum during the cold antarctic periods, Green- 
land and the arctic regions would, during the warm interven- 
ing periods, be probably free of ice and enjojang a mild and 
equable climate." 
Instead of this, however, we find the north pole of Mars 
capped with its snow and ice as regularly and almost as ex- 
tensively as his south pole, and this wintery accumulation 
lasts as long into the northern summer as does its southern 
counterpart into the warm season of the southern hemisj)here. 
If any difference existed between the glacial condition of the 
two planets it should be one that indicates greater intensity 
both of the cold and warm eras on Mars in consequence of the 
high eccentricity that now elongates his orbit so far beyond 
that of the earth. 
*Capt. CViok's Second Voyage, vol. ii. p. 2.32, 1875. 
