This may explain the very
rapid diminution of the polar ice-caps in the summer of either, but
especially of the Southern hemisphere; and also the occasional
appearance of large dark spots in their midst, where the shallow snow
has probably been swept away by the rare storms of this planet from an
extensive land surface. It is supposed that no inconsiderable part of
the ice and snow immediately surrounding the poles covers land; but,
though balloon parties have of late occasionally reached the poles,
they have never ventured to remain there long enough to disembark and
ascertain the fact.
Towards evening the stream turned more decidedly to the north, and at
this point Esmo brought out an instrument constructed somewhat on the
principle of a sextant or quadrant, but without the mirror, by which
we were enabled to take reliable measures of the angles. By a process
which at that time I did not accurately follow, and which I had not
subsequently the means of verifying, the distance as well as the angle
subtended by the height was obtained. Kevima, after working out his
father's figures, informed me that the highest peak in view--the
highest in Mars--was not less than 44,000 feet.
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