While Mawson was still engaged on cooking experiments, Mackay and I went to the highest point of the island, and chose a spot for a cairn to mark our depot and Mackay began to build the cairn.
It had, of course, become clear to us, from what we had already seen of the cracking sea-ice, combined with our slow progress, that our retreat back to camp from the direction of the Magnetic Pole would probably be cut off altogether through the breaking up of the sea-ice.
Under these circumstances we resolved to take the risk of the Nimrod returning safely to Cape Royds, where she would be instructed to search for us along the western coast; and also the risk of her not being able to find our depot and ourselves.
We knew that there was some danger in this course, but we also felt that we had got on so far with the work entrusted to us by our commander that we could not honourably turn back.
Under these circumstances we each wrote farewell letters to those who were nearest and dearest, and at 4.30 A.M. on the following morning we posted them in one of our empty dried-milk tins, which had an air-tight lid, and, having walked up to the cairn, I lashed our post-office to the flagstaff by means of cord and copper wire.
There we also left several bags of geological specimens, and with lighter loads were prepared to go onwards towards the Pole.
It was later than usual when we left our depot, and as the sun's heat was already thawing the surface of the snow our progress was painfully slow. So terribly hard, indeed, was it to get along at all, that, after going two miles, we camped and resolved to go on again at midnight, when we hoped to avoid the sticky surface.
This experiment was fairly successful, and by November 5 we were opposite to a most interesting panorama some twenty miles north of Granite Harbour.
During that same day we had a very heavy surface to hamper and tire us, but as an offset to these troubles we had that night, for the first time, the use of a new frying-pan, ingeniously constructed by Mawson out of one of our empty paraffin tins. Indeed, Mawson's cooking experiments continued to be highly successful and entirely satisfactory to the party.
At this time we encountered a good deal of brash ice, and noticed that this type of ice surface was most common in the vicinity of icebergs. The brash ice is, I think, formed by the icebergs surging to and fro in heavy weather and crunching up the sea-ice near to them. The sea-ice, of course, refreezes, producing a surface covered with jagged edges and points.