The sounding equipment was new on this expedition, never having been taken on previous trips, and consisted at the start of two thousand fathoms (twelve thousand feet) of specially made steel piano wire in two reels of a thousand fathoms each, the net weight of each reel being twelve and a fraction pounds. The sounding-lead was cut down from its original weight to a final weight of about fourteen pounds, and had at the lower end an automatic clam-shell device for bringing up samples of the bottom.
The sounding wire was marked in one hundred fathoms by bits of brass soldered to it, and was wound round a wooden reel that could be attached temporarily either to the front or rear end of a sledge for making soundings, and then, by the attachment of cranks at both ends, the wire could be reeled up again when the sounding had been completed.
Some five hundred fathoms of this were lost by breaks in the earlier part of the trip north, but when Bartlett left me there were some fifteen hundred fathoms left, and fearing to lose more of it, I did not attempt to make any more soundings until just south of the pole on the return trip. It was fortunate that I did this, as in making the sounding the mishap which I had feared occurred, resulting in the loss of all but a hundred or two feet of the wire and making it impossible for me to make further soundings on the return trip, as I had planned, to supplement those made by Marvin and Bartlett.
The one sounding, however, showing that the central polar ocean is probably not less than two miles in depth, is of pronounced interest to the geographer and oceanographer.
Our instruments were all kept in a special instrument box. This was a milk case covered carefully with canvas to keep the fine snow from being blown into it, and reinforced with tin on the corners to withstand rough usage on the trip. The sextant was suspended from the cover of the box to protect it from shocks.
The instrument box was always stowed on the middle of the special sledge used to carry such equipment, where it would get the least motion and pounding, and rested on a cushion of spare clothing.
The theodolite, in its box, was carried in a canvas case in front of the upstanders of the sledge, resting on some item of spare fur clothing, and kept in place by elastic lashings of rawhide line.
The camera, thermometers, note-books, field-glasses, and Winchester carbine were carried in canvas pockets by the upstanders of the sledge, and arranged in such a way that any one of them could be obtained instantly for use without having to unlash any portion of the load.
CHAPTER X
SLEDGE-TRAVELING
Sledge-traveling is the other twin of ice navigation, the two together forming polar exploration. The purpose of sledge-traveling is the transformation of food into miles, and the test of its perfection is the maximum number of miles for the minimum amount of food. Sledge-traveling may be of several kinds. It may be over the frozen surface of polar seas, or along a coast line, or over the elevated snow surfaces of the great interior ice-caps of Greenland and the antarctic continent.