At the seventy-six-mile camp we tried the experiment of a break-wind. The tent was so small and light that it was necessary to protect it in the heavy winds. Hurley and I took about three-quarters of an hour to build the first one, but later we improved, getting into the knack of hewing snow with a sharp-pointed shovel.
That night in bag I wrote: "The result of the breakwind is that for once we have the wind bluffed. It is blowing seventy-five miles per hour—a full hurricane—but all the viciousness is taken out of the flapping and there will be no damage done to the tent by morning."
The wind was too strong for travelling early in the day (November 25). While outside we suddenly observed two snow petrels. It was hard to realize that they had actually flown seventy-six miles inland to a height of two thousand four hundred and fifty feet. I dashed inside for the fishingline; Hurley got out the camera. They were a beautiful sight, hovering with outspread wings just above the snow, tipping it with their feet now and then, to poise without a flutter in a sixty-five-mile gale. Hurley secured a couple of "snaps" at the expense of badly frost-bitten hands. Just as I arrived with the line hooked and baited, the birds flew away to the north-east; our visions of fresh meat went with them. The line was always ready after this.
Towards evening the wind dropped suddenly to twenty miles per hour. Our camp was stationed on the southern side of the large valley we had entered on the 18th, and we could identify the ridge crossed on that date, blue and dim, forty miles away to the north. To the north-east could be seen a distinct dip in the skyline, indicating the bed of the valley, on whose northern side the dip met the higher skyline in a steep bluff, twenty-five miles off. This bluff under the glasses was of heavily crevassed, blue ice.
The wind did not rise again much until 10 P.M., when we had moved on seven and a half miles, rising about three hundred feet over several ridges and practically losing our view to the north.
A steady breeze on the 26th, and, on the whole, good light, allowed us to make twelve miles.
Each day, now, Webb took an approximate magnetic dip and declination in the lee of the break-wind. This was necessary in order to get some idea of local disturbances. Also, it gave us some vague idea as to the direction in which lay the South Magnetic Pole. For instance, at the eighty-three-and-three-quarter-mile camp, the needle showed the Pole to be 18 degrees east of true south, while at our lunch camp that day, six miles farther on, it was given as 50 degrees east of south. The dip was so great that our prismatic compass would not set closer than about 15 degrees, but the long compass needle of the dip-circle, though of course sluggish, continued to give excellent results.
Under these conditions it is obvious that the magnetic needle is quite useless for steering purposes. The sun compass proved itself a more than efficient substitute. On a snowfield there is usually a total absence of landmarks of any kind, so the direction of wind, sastrugi, or perhaps a low cloud is found with the sun-compass, frequently checked, and the course kept accordingly. On camping we would generally carefully note the direction in which the sledge was left, in case the next day proved overcast. Thus we would march in the morning by the wind's direction till the sun, gleaming through the clouds for a few moments, enabled us to use the compass again.
Sastrugi, only six inches high, seen on the 26th, showed the effects of wind-erosion exquisitely. In an individual case the windward end of a sastruga might be completely undercut for six or nine inches, leaving a hard crust, sometimes only one-eighth of an inch in thickness and a couple of inches wide. This would sag downwards under its own weight in a fine curve till the tip rested on the snow beneath. It is marvellous how such a delicate structure can withstand the heavy wind.
November 27 proved a very hard day. The wind kept up sixty miles per hour all the time, so that, after taking four hours to do four and three-quarter miles, we were all thoroughly exhausted. It was not a great run, but the century was hoisted—one hundred and three-quarter miles by sledge-meter; altitude two thousand nine hundred feet. There was a mild celebration that night over a square of butter-scotch and half an ounce of chocolate, besides the regular hoosh and cocoa.