64 
On November 25, 1841, the expedition again shaped its 
course southwards. On December 16, in 57° S. lat., Ross 
reached the first ice, and on January 1, 1842, crossed the 
Polar Circle in 156° 28’ W. long., surrounded at times by 
pack-ice. On February 2, 1842, in 68° 23’ S, lat. and 159° 52’ 
W. long., the vessels reached open water, and on the 
23rd of the same month, they approached, in 77° 49’ S. 
lat. and 162° 36’ W. long., a perpendicular wall of ice, 
only half the height of that in the neighbourhood of 
Mount Terror. On this day also they reached in 161° 27’ 
W. long. their highest latitude, 78° 9’ 30" S., where they 
observed unmistakeable signs of neighbouring land. On 
the following day was commenced the return journey, and 
on April 6 the ships anchored at Port Louis, in the 
-Falkland Islands. 
On December 17, 1842, Ross set out a third time for the 
far south, this time to explore D’Urville’s Louis Philippe 
Land, and to penetrate to the region which Weddell had 
reached in 74° 15’. There is little to record for our 
present purpose concerning this journey, but that, amid 
the greatest difficulties and dangers from the ice, the two 
plucky ships penetrated as far south as 71° 30’in 14° 
51’ W. long., on March 5, 1843. On September 2, the 
-two ships Zyebus and Terror reached England, and 
fifteen months later, under the guidance of Sir John 
Franklin, they set out again towards the north, from 
which they never returned. 
Such is a brief review of the progress of geographical 
knowledge in reference to the South Polar regions. 
In what follows it is not intended to give a comprehen- 
sive analysis of the valuable material contained in the 
journals of the various voyages concerning the nature and 
physical conditions of these regions, but only to bring 
into prominence what is of greatest importance, and, incon- 
nection therewith, what is of importance to any expedition 
that may yet be organised, to draw some general conclu- 
sions as to the form of the South Polar regions. By this 
means a rational plan may be suggested for the further 
investigation of these regions. 
In these observations the conditions as to ice claim our 
attention in the first place, as they enable us to draw im- 
portant conclusions with respect to the extent of the land 
and the currents inside the Polar Circle, With reference 
to the latter, the drift-ice is of special value, as it enables 
us to recognise them in spite of the surface-currents 
caused by the winds and obliterating the main pheno- 
mena. In the southern hemisphere drift icebergs of 
200, 300, and even more feet in height above the water 
are common; and if we take into consideration that 
their depth under the water must be six or seven 
times greater, we shall be able to understand that the 
movement of these ice-masses, which, moreover, are of 
colossal extent horizontally, must be the result of various 
forces working upon them. Under-currents, surface- 
currents, and prevailing winds, have to be considered in 
interpreting this phenomenon, according to the size and 
proportion of the mass presented ; though the compara- 
tively feeble surface-currents are of subordinate impor- 
tance. 
It would lead us too far here were we to attempt a 
thorough discussion of all the modifying causes and phe- 
nomena; it need only be mentioned that the water- 
masses of the Polar zone move, so to speak, to lower 
aa wa 
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[Wov. 28, 1872 
“ Antarctic Drift.” And by the south-east winds, which — 
prevail in the southern summer, colossal masses of — 
ice during that season push their way northwards, where 
they partly break up, but partly also are driven back by 
the north-west winds of autumn to the south. Although 
nothing certain can be said concerning their course 
towards the Pole, and only in particular circumstances is 
a south-easterly return movement established, yet it may 
in general be stated with regard to the masses which out- 
last the summer, that their northward and southward 
course may be explained by a periodical prevalence of — 
the impulse from the surface or under-current. In 
winter, when the Antarctic drift-current, on account of the 
smaller differences of temperature and evaporation in 
lower latitudes, is less powerful, will the impulse, strength- 
ened by the north-west winds, be directed towards the — 
south-east or the south? Also, the movements of the ice 
during the other seasons can only be explained in this 
way ; and on this account is the study of the various 
ice-charts of considerable advantage, especially the chart 
of the British Admiralty, on which are registered the re- 
sults obtained from the commerce of the world. 
The glacier ice-walls, of which we have accounts in 
several narratives of voyages, are, through the almost 
unbroken, and in winter specially rapid formation of ice, 
pushed continually farther and farther on into the sea, 
until at last, being insufficiently supported at the bottom, 
and subject to the buffetings of the waves, they break into 
pieces. Towards the end of the cold season this disinte- 
gration is still further assisted by the great differences of — 
temperature betwixt air and water in high south latitudes, 
and with the setting in of September commences the 
journey of the masses of drift-ice from the south. Jt is in 
consequence of this that during the southern winter, — 
scarcely any drift-ice is found on the great highways of 
the world’s commerce. The result of a strict comparison — 
is that the frequency of the occurrence of ice in June and 
December is in the proportion of 1 to 13. Further, that 
the prevalence of the drift-ice is greater in March and 
April than in September and October, is only a further 
proof of what has been stated, seeing that in the last- 
mentioned months the ice is still in the neighbourhood of 
the spot where it was formed, while in the former months 
it has either not yet been broken up, or has not got 
beyond the bounds of traffic on its return journey. 
The masses of drift-ice do not everywhere move equally 
far to the north: in some places they are met with much 
nearer the equator than in others, as will be seen if we 
examine the region around the poles on the charts on which 
the position of the ice in the various months is laid down. 
The causes of this inequality are to be seen partly in the 
conditions of the current, but also in the difference of the 
distances from the pole of the places of formation of the 
various masses of ice : indeed, the greater this distance is, 
so much farther to the north, ceferis paribus, will the ice 
be driven. We might now attempt to construct an 
average boundary line for the equatorial drift-ice, but 
from the variety of the boundaries and the lack of material 
for this purpose, its course would be very indefinite. We 
shall best arrive at useful results if we draw these bound. 
aries in accordance with trustworthy notes, leaving mean- — 
while peculiar, and evidently altogether abnormal circum- 
