At these low temperatures the ice became very hard and brittle, and was readily cracked or broken up by a blow or by packing. In the summer, on the other hand, when its temperature was near melting-point, the ice became tough and plastic, and was not so readily broken up under packing. This difference between the condition of the ice in summer and winter was apparent also to the ear, as the ice-packing in winter was always accompanied by the frequently mentioned loud noises, while the packing of the tough summer ice was almost noiseless, so that the most violent convulsions might take place close to us without our noticing them.
In the immediate vicinity of the Fram the ice remained perfectly at rest the whole year through, and she was not at this time exposed to any great amount of pressure; she lay safe and secure on the ice-floe to which she was firmly frozen; and gradually, as the surface of the ice thawed under the summer sun, she rose up higher and higher. In the autumn she again began to sink a little, either because the ice gave way under her weight, or because it melted somewhat on the under surface, so that it no longer had so much buoyancy as before.
Meanwhile, life on board went on in its usual way. Now that we had daylight, there was of course more work of various descriptions on the ice than had been the case during the winter. I have already alluded more than once to our unsuccessful endeavors to reach the bottom by sounding. Unfortunately we were not prepared for such great depths, and had not brought any deep-sea sounding apparatus with us. We had, therefore, to do the best we could under the circumstances, and that was to sacrifice one of the ship’s steel cables in order to make a lead-line. It was not difficult to find sufficient space on the ice for a rope-walk, and although a temperature of from 22° Fahr. below zero (-30° C.) to 40° Fahr. below zero (-40° C.) is not the pleasantest in which to manipulate such things as steel wire, yet for all that the work went on well. The cable was unlaid into its separate strands, and a fresh, pliant lead-line manufactured by twisting two of these strands together. In this way we made a line of between 4000 and 5000 metres (2150 to 2700 fathoms) long, and could now at last reach the bottom. The depth proved to range between 3300 and 3900 metres (1800 to 2100 fathoms).
This was a remarkable discovery, for, as I have frequently mentioned, the unknown polar basin has always been supposed to be shallow, with numerous unknown lands and islands. I, too, had assumed it to be shallow when I sketched out my plan (see page 24), and had thought it was traversed by a deep channel which might possibly be a continuation of the deep channel in the North Atlantic (see page 28).
From this assumption of a shallow Polar Sea it was concluded that the regions about the Pole had formerly been covered with an extensive tract of land, of which the existing islands are simply the remains. This extensive tract of polar land was furthermore assumed to have been the nursery of many of our animal and plant forms, whence they had found their way to lower latitudes. These conjectures now appear to rest on a somewhat infirm basis.
This great depth indicates that here, at all events, there has not been land in any very recent geological period; and this depth is, no doubt, as old as the depth of the Atlantic Ocean, of which it is almost certainly a part.
Scott-Hansen Johansen taking water temperatures
Another task to which I attached great importance, and to which I have frequently alluded, was the observation of the temperature of the sea at different depths, from the surface down to the bottom. These observations we took as often as time permitted, and, as already mentioned, they gave some surprising results, showing the existence of warmer water below the cold surface stratum. This is not the place to give the results of the different measurements, but as they are all very similar I will instance one of them in order that an idea may be formed how the temperature is distributed.
This series of temperatures, of which an extract is given here, was taken from the 13th to the 17th of August.