316 The History of our Earth. [July, 
Now we are well aware that at present the southern 
hemisphere is colder than the northern. ‘‘ Sandwich Land, 
which is in the same latitude as the North of Scotland, is 
covered with ice and snow the entire summer; and in the 
island of South Georgia, which is in the same parallel as 
the centre of England, the perpetual snow descends to the 
very sea-beach. In the Straits of Magellan, lat. 53° S., the 
direct heat of the sun ought to be as great as that in the 
centre of England. Yet in the midst of summer, when 
the day was eighteen hours in length, the thermometer 
seldom rose above 42° to 44°, and,never above 51° F.”’ Ice- 
bergs 1000 feet in height have been sighted in latitudes as 
low as 37 S. 
If we now imagine that the earth’s orbit were at present 
about or near its limit of maximum eccentricity, the 
southern hemisphere, having its winter solstice in aphelion, 
would have a summer too short, not by eight, but by thirty- 
six days, and would now be suffering all the rigours of a 
Glacial epoch. Great part of Australia, New Zealand, 
South Africa, and of temperate South America, would be 
overlaid with ‘‘thick-ribbed”’ ice. The region of highest 
temperature, instead of lying, as now, near the Equator, 
would be driven northwards as far, perhaps, as the tropic of 
Cancer, whilst the southern half of the torrid zone would be 
barely habitable. Meantime the condition of the northern 
hemisphere would be just the reverse. Its winter half year 
would be thirty-six days shorter than the summer. Thus 
the portion of the year during which snow and ice could 
accumulate would be largely abridged. Every season would 
see a decrease in the circumpolar ice-mass, and a corre- 
sponding quantity of the sun’s rays, no longer wasted in 
thawing snow, would be available for raising the general 
temperature of the arctic regions. 
A natural result would be that trees such as now flourish 
in Central Europe, would grow in Greenland and Spitzbergen 
—as has been the case aforetime—whilst Western Europe 
would display a vegetation of a semi-tropical character. 
A great period of this kind, when a high eccentricity of the 
earth’s orbit will produce Glacial epochs alternately in the 
northern and southern hemispheres, awaits us in the remote 
future. ‘It consists of three maxima, one hundred 
thousand years apart. These will occur at the periods 
800,000, 900,000, and I,000,000 years to come.” 
It is interesting to examine how far this view of a Glacial 
epoch, successively invading either hemisphere, harmonises 
with certain suggestive speculations put forward by Mr. 
