We entered the pack more or less on this meridian, and have been rewarded by encountering worse conditions than any ship has had before.

Worse, in fact, than I imagined would have been possible on any other meridian of those from which we could have chosen.
'To understand the difficulty of the position you must appreciate what the pack is and how little is known of its movements.
'The pack in this part of the world consists (1) of the ice which has formed over the sea on the fringe of the Antarctic continent during the last winter; (2) of very heavy old ice floes which have broken out of bays and inlets during the previous summer, but have not had time to get north before the winter set in; (3) of comparatively heavy ice formed over the Ross Sea early in the last winter; and (4) of comparatively thin ice which has formed over parts of the Ross Sea in middle or towards the end of the last winter.
'Undoubtedly throughout the winter all ice-sheets move and twist, tear apart and press up into ridges, and thousands of bergs charge through these sheets, raising hummocks and lines of pressure and mixing things up; then of course where such rents are made in the winter the sea freezes again, forming a newer and thinner sheet.
'With the coming of summer the northern edge of the sheet decays and the heavy ocean swell penetrates it, gradually breaking it into smaller and smaller fragments.

Then the whole body moves to the north and the swell of the Ross Sea attacks the southern edge of the pack.
'This makes it clear why at the northern and southern limits the pieces or ice-floes are comparatively small, whilst in the middle the floes may be two or three miles across; and why the pack may and does consist of various natures of ice-floes in extraordinary confusion.
'Further it will be understood why the belt grows narrower and the floes thinner and smaller as the summer advances.
'We know that where thick pack may be found early in January, open water and a clear sea may be found in February, and broadly that the later the date the easier the chance of getting through.
'A ship going through the pack must either break through the floes, push them aside, or go round them, observing that she cannot push floes which are more than 200 or 300 yards across.
'Whether a ship can get through or not depends on the thickness and nature of the ice, the size of the floes and the closeness with which they are packed together, as well as on her own power.
'The situation of the main bodies of pack and the closeness with which the floes are packed depend almost entirely on the prevailing winds.

One cannot tell what winds have prevailed before one's arrival; therefore one cannot know much about the situation or density.
'Within limits the density is changing from day to day and even from hour to hour; such changes depend on the wind, but it may not necessarily be a local wind, so that at times they seem almost mysterious.

One sees the floes pressing closely against one another at a given time, and an hour or two afterwards a gap of a foot or more may be seen between each.
'When the floes are pressed together it is difficult and sometimes impossible to force a way through, but when there is release of pressure the sum of many little gaps allows one to take a zigzag path.'.