408 THE ANTARCTIC MANUAL. 
way south we did not fall in with ice-islands until we reached latitude 
61° 8. The Peacock was the first to return, and nearly upon the track 
by which we had gone south; the last seen by her was in 55° 8. The 
Vincennes, on her return fifty days later, saw them in 51° 8. The Por- 
poise, about the same time, in 53°S. The observation in the Vincennes 
gives a distance of ten degrees of latitude, or 600 miles to be passed 
over in fifty days, which would give about half a mile an hour ; or, 
taking the Peacock’s observations, a more rapid rate would be given, 
nearly three-fourths of a mile. Many icebergs were met in the latitude 
of 42°S., by outward-bound ships to Sydney, in the month of November; 
these, I learned, were much worn, and showed lofty pinnacles, ‘exhibit- 
ing no appearance of having ever been of a tabular form. These no 
doubt are such as were detached during a former season, and being dis- 
engaged from the barrier, would be naturally, early the next season, 
drifted by the easterly current as well as the westerly wind, and would 
pursue the direction it gives them. They would, therefore, be driven 
to the north-east as far as the south-west winds prevail, and when these 
veer to the westward would receive an easterly direction ; it is where 
these winds prevail that they are most frequently found by the out- 
ward-bound vessels—between the latitudes of 40° and 50°S. 
Respecting the period of time required for the formation of these 
ice-islands, much light cannot be expected to be thrown on the subject; 
but the few facts derived from observations lead to some conclusions. 
Many of them were measured, and their altitude found to be from 50 
to 250 feet; eighty distinct stratifications were counted in some of 
the highest, and in the smallest thirty, which appeared to average a 
little more than two fect in thickness. Supposing the average fall of 
snow in these high latitudes to be an inch a day, or 30 feet a year, the 
largest icebergs would take more than thirty years to form. They 
were seen by us in all the stages of their growth, and all bore unequi- 
vocal marks of the same origin. The distance from the land at which 
they were forming, fully satisfied me that their fresh water could only 
be derived from the snows, etc. 
The movement of the ice along the coast is entirely to the west- 
ward, and all the large range of ice-islands and bergs were found in 
that direction, while the eastern portion was comparatively free from 
it. A difference was found in the position of the floe-ice by the dif- 
ferent vessels, caused rather by the wind than by the tide. When the 
Vincennes and Porpoise passed the opening by which the Peacock entered, 
it was found closed, although only twenty-four hours had elapsed. It 
has been seen that the ice had much movement during the time the 
Peacock was beset by it, and the bay was all but closed when she 
effected her escape. Another instance occurred where the Porpoise, in 
about the longitude of 130° E., found the impracticable barrier a few 
miles further south than the Vincennes did six or seven days after; but 
