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742 KERGUELEN’S VOYAGE TO THE NORTH.
to freezing ; for the air which is at reft on the furface of a liquid, participates by de-
grees of the coldnefs thereof, and keeps at that temperature ; fo that the fubtil matter
which circulates in the interftices of the liquid, and the motion of which is always in
proportion to the motion of that which immediately furrounds it, is not yet fufficientl
weakened to admit of freezing taking place; but if the communication of cold to the
furface of the liquid be haftened by a violent impulfion of the air, which immediately
adjoins its furface, and fubftituting (which the wind does) a more cold and denfe air,
fuch as is requifite for occafioning congelation, the fubtil exterior matter impofed on
the liquid will be weakened, and by this means, that in the interior as well, which mutt
neceflarily lofe in its action as much as the external, in order to preferve an equilibrium.
Neverthelefs, fhould the freth airs remain at reft, freezing would not fucceed ; but if
continually cold air in fucceflfion fhould drive away that which preceded it, until
that which fhould be of a temperature to excite freezing fhould be in contact; it is evi-
dent, that ultimately it muft communicate its frigidity to the liquid, and paralize the
motion of the internal matter fo as to occafion froft; thus wind produces froft, as a
fan excites in our frame the fenfation of coolnefs, by expelling from around us the airs
warmed by our fecretions and breathing.
The third accidental caufe of the formation of ice, is the diminution of the exterior
heat of the fun, arifing from the diftance of its fource, the oblique and ungain difpofi-
tion of the furface which receives its rays, and, laftly, the interpofition of vapours, and
denfe and dark atmofphere, fuch as a fog, which in meafure intercepts its rays.. It is
to be obferved as well, that the obliquity of the globe caufes the folar rays to be inter-
‘cepted by a greater column of air.
There are befides many other accidental caufes, fuch as climate, local circumftances,
and the fuppreflion of the central afpirations, or vapours, which are continually arifing
from the bofom of the earth. Many naturalifts, and particularly a celebrated acade-
mician, M. Dortous de Mairan, have maintained the theory of a central fire.
From this fhort difflertation, and from examination of circumftances, it is eafy to
conceive that the fea may freeze in the neighbourhood of the poles, even as far as ©
forty leagues from the fhore*; and that confiderable maffles of ice may be met with
at fea; but how are we to account for the pyramids, the iflands, and towering heaps
of ice of fix or eight leagues in length which are found floating ? Thefe mountains of ice,
formed at firft by the union of different maffes, owe their height to fnow, and rain,
frozen on its reaching them; and Iam inclined to imagine, that when become of a
certain fize, they always increafe in bulk. A learned Englifhman, who wrote in the
middle of the laft century, adopted the idea of their being perpetual, efpecially near the
poles, and computed that they rofe fo high as to caufe the figure of the earth to be
fenfibly lengthened thereby at the extremities of its axisT: it is on this theory that he
explains the elliptic appearance of the fhadow of the earth on the difk of the moon in two
eclipfes, the one obferved by Kepler, the other by Tycho Brahe; but all thefe reafon-
ings are unfounded. ‘The feais not frozen round the poles for a greater diftance than
fifteen or twenty leagues from land, and the mountains of ice which various navigators
have feen, have no more effect in altering the rotundity of the globe, than five or fix
grains of millet floating on the furface of a globe of four or five feet in diameter.
The twenty-fecond, the wind was N. W., avery frefh gale, the weather foggy with
a heavy fea; and peceiving every appearance of a tempeft, I decided on making land to
take fhelter in the gulph of Patrixfiord. At eleven in the morning, during a moment’s
* Memoires de Trévoux. + Mr. Childrey’s Hiftory of the Singularities of Scotland.
I clearnefs,
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