9 4
*77*.
Decembei
A VOY AGE ROUND THE WORL D .
volume of ice is to that of fea-water, nearly as ten to nine:
confequently, by the known rules of hyclroftatics, the vo-
lume of ice which rifes above the furface of the water, is to
that which finks below ir, as one to nine. Suppofing the
piece which we now faw to be entirely of a regular figure,
its depth under water mud have been one thoufand eight
hundred feet, and its whole height two thoufand feet, allowing
its length as abovementioned two thoufand feet, and
its breadth four hundred feet, the whole mafs muft have
contained one thoufand fix hundred millions cubic feet of
ice.
Thefe prodigious pieces of ice, in all probability, drift
but very flowly and imperceptibly, fince the greateft
part of them being under water, the power of winds and
waves can have but little effedt; currents perhaps are the
principal agents which give them motion, though I much
queftion, whether their velocity is ever confiderable enough
to carry them two miles in four-and-twenty hours. At the
time we met with this firft ice, all our conjedlures about its.
formation could not amount to more than bare probabilities,
and had not fufficient experience to fupport them :
but after we have made the tour of the globe,, without
finding the Southern Continent, the exiftence of which has
been fo univerfally believed in Europe; it feems in the
higheft degree reafonable to fuppofe this floating ice to
have
have been formed in the fea * ; an idea the more probable, '77'-
r ’ D e c em b e r ,
as repeatéd and decifive experiments have evinced, that
falt-water may be frozen.
This ice likewife ferved to fliew us the great difference
between the temperature of the northern and fouthern he-
mifphere. We were now in the midft of December, which
anfwers to our June, and the latitude obferved at noon
gave only 5 1 0 5 fouth, notwithftanding which we had
already paffed feveral pieces of ice, and the thermometer
flood at 3 69. The want.of land in the fouthern hemifphere
feems to account for this circumftance, fince the fea, as a
tranfparent fluid, abforbs the beams of the fun, inftead of
reflecting them.
On the n th of December, about three o’ clock in the Friday,,,
afternoon, we paffed to leeward of a large piece, or ifland
of ice, at leaf! half a mile in length. The thermometer
on deck, which had been at 36° about two o’clock, was
nfen to 41 on account of the fair funfhine, which continued
all the afternoon: when we came abreaft of the ice,
the wind diredtly blowing from thence, it gradually funk
© -------------© > “‘uu6 ul. uuiucs nnea with
fea-water with him, taken up in different latitudes, which Being brought to Paris -
fromBreft in the midft of winter, the water in them froze fo-as to break them •
th em e was perfeflly frefh, and the reftduum of brind was ru'n' out. See H f
Voyage au Senegal, p. i 9o. Mr. Edward Nairne, F . R/S.. has .made expertm
m durins th? hard froftin ^ ^ the tx yi. »01»»= of
the Philofophical Tranfadtions, which put it beyond a doubt, that folidand frelh
may be formed from fea-water.
to