ourse of the winter
reached a considerable thickness.[250]

In this immense ice-sheet there often arose in the course of the
winter cracks of great length. They ran uninterruptedly across newly
formed ice-fields, and old, high ground-ices. One of the largest of
these cracks was formed on the night before the 15th December right
under the bow of the vessel. It was nearly a metre broad, and very
long. Commonly the cracks were only some centimetres broad, but,
notwithstanding this, they were troublesome enough, because the
sea-water forced itself up through them to the surface of the ice
and drenched the snow lying next to it.

The causes of the formation of the cracks were twofold. Either they
arose from a violent wind disturbing somewhat the position of the
newly formed ice, or through the contraction of the ice in severe
cold. The formation of the cracks took place with a more or less
loud report, and, to judge from the number of these reports, more
frequently than could be observed from the appearance of the
snow-covered ice. Thus even during severe cold the apparently
continuous ice-sheet was divided into innumerable pieces lying in
the close proximity of each other, which either were completely
loose or bound together only by the weak ice-band which was
gradually formed under the snow on the surface of the water which
had forced its way into the crack. Up to a distance of about six
kilometres from the shore the ice in any case lay during the course
of the whole winter nearly undisturbed, with the exception of the
small cracks just mentioned. Farther out to sea, on the other hand,
it was in constant motion. So-called _polynias_ or open places
probably occur here all the year round, and when the weather was
favourable we could therefore nearly always see a blue water sky at
the horizon from true N.W. to E. A southerly wind after some days
brought the open water channel so near the vessel that it was
possible to walk to it in a few hours. It then swarmed with
seals--an indication that it was in connection with a sea that was
constantly open. The neighbourhood of such a sea perhaps also
accounts for the circumstance that we did not see a single seal-hole
in the ice-fields that surrounded the vessel.

The ground-ice, to which the _Vega_ was moored on the 29th
September, and under which she lay during the course of the winter,
was about forty metres long and twenty-five metres broad; its
highest point lay six metres a