In the southern hemisphere spring lasts 149 days; summer, 147 days;
autumn, 191 days; and winter, 181 days.

Thus, in the northern hemisphere spring and summer together amount to
372 days, and autumn and winter to 296 days.

In the southern hemisphere, however, spring and summer have 296 days,
whilst autumn and winter last 372 days; so that the winter period of
the year is 76 days longer than in the northern hemisphere.

On the earth the winter portion of the year is seven days longer in the
southern hemisphere than it is in the northern hemisphere.

For this reason, our south polar snow-cap is larger than the north polar
cap; and we should naturally expect to find a similar condition upon
Mars, only greatly accentuated. Astronomical observation shows that this
is the case, for while the northern snow-cap on Mars attains a maximum
diameter of slightly under 80 deg., the southern snow-cap attains a
maximum diameter of over 96 deg. The snow-caps are not perfect circles,
but irregular in shape, and are, moreover, not exactly opposite to each
other.

Notwithstanding its much greater area the southern snow-cap melts to a
greater extent than the northern snow-cap does, owing to the intensity
of the heat at the melting period. The northern snow-cap usually melts
until the diameter is reduced to about 6 deg., whilst the much larger
southern cap may be reduced to about 5 deg. In the year 1894 it
disappeared entirely! The summer must have been unusually hot.

So far as can be gathered from the records of our whaling and polar
expeditions, it would appear that our north polar snow-cap is from 20
deg. to 30 deg. in diameter when at the minimum; whilst the southern
snow-cap is nearly 40 deg. in diameter when smallest.

* * * * *

We had arrived upon Mars on the 24th of September 1909, according to
terrestrial reckoning; but according to the Martian date it was then the
26th of June in the southern hemisphere, where Sirapion, our
landing-place, is situated. The season was, therefore, midsummer, and
as Sirapion is in latitude 25 deg. south and in the sub-tropical zone,
the temperature was fairly high. The mornings were much more clear and
brilliant than those on our earth; the warmth and general "feel" of the
air at that time reminding me very much of what it is like in the south
of England between seven and eight o'clock on a hot sunny day. Those who
enjoy an early morning walk know how delightf