Returning to the fortunes of the air-tractor sledge, which was to start west early in December. Bickerton has a short story to tell, inadequate to the months of work which were expended on that converted aeroplane. Its career was mostly associated with misfortune, dating from a serious fall when in flight at Adelaide, through the southern voyage of the 'Aurora', buffeted by destructive seas, to a capacious snow shelter in Adelie Land—the Hangar—where for the greater part of the year it remained helpless and drift-bound.
Bickerton takes up the story:
I had always imagined that the air-tractor sledge would be most handicapped by the low temperature; but the wind was far more formidable. It is obvious that a machine which depends on the surrounding air for its medium of traction could not be tested in the winds of an Adelie Land winter. One might just as well try the capabilities of a small motor-launch in the rapids at Niagara. Consequently we had to wait until the high summer.
With hopes postponed to an indefinite future, another difficulty arose. As it was found that the wind would not allow the sea-ice to form, breaking up the floe as quickly as it appeared, the only remaining field for manoeuvres was over the highlands to the south; under conditions quite different from those for which it was suited. We knew that for the first three miles there was a rise of some one thousand four hundred feet, and in places the gradient was one in three and a half. I thought the machine would negotiate this, but it was obviously unsafe to make the venture without providing against a headlong rush downhill, if, for any reason, power should fail.
Suggestions were not lacking, and after much consideration the following device was adopted:
A hand rock-drill, somewhat over an inch in diameter, was turned up in the lathe, cut with one-eighth-inch pitched, square threads and pointed at the lower end. This actuated through an internal threaded brass bush held in an iron standard; the latter being bolted to the after-end of a runner over a hole bushed for the reception of the drill. Two sets of these were got ready; one for each runner.
The standards were made from spare caps belonging to the wireless masts. The timely fracture of one of the vices supplied me with sufficient ready-cut thread of the required pitch for one brake. Cranked handles were fitted, and the points, which came in contact with the ice, were hardened and tempered. When protruded to their fullest extent, the spikes extended four inches below the runners.
The whole contrivance was not very elegant, but impressed one with its strength and reliability. To work the handles, two men had to sit one on each runner. As the latter were narrow and the available framework, by which to hold on and steady oneself, rather limited, the office of brakesman promised to be one with acrobatic possibilities.
To start the engine it was necessary to have a calm and, preferably, sunny day; the engine and oil-tank had been painted black to absorb the sun's heat. On a windy day with sun and an air temperature of 30 degrees F., it was only with considerable difficulty that the engine could be turned—chiefly owing to the thickness of the lubricating oil. But on a calm day with the temperature lower -20 degrees F. for example—the engine would swing well enough to permit starting, after an hour or two of steady sun. If there were no sun even in the absence of wind, starting would be out of the question, unless the atmospheric temperature were high or the engine were warmed with a blow-lamp.
It was not till November 15 that the right combination of conditions came. That day was calm and sunny, and the engine needed no more stimulus than it would have received in a "decent" climate.