Page:McClure's Magazine volume 10.djvu/114

300 a great influence on the conditions of the atmosphere, the circulation of ocean currents, and many other physical conditions. We also want to know the exact depth of this Polar sea in its full extent, and the water temperatures in the various strata from the surface down to the bottom. And then we must know more about the formation of the ice in that sea: the conditions which are necessary for its freezing, how the ice travels across the sea, how thick it grows, etc. A perfect knowledge of all this will not only help us to understand better the climatic conditions of the northern regions, and, we could say, of the whole surface of the globe of today, but it will perhaps throw some light on the many strange climatic changes which have taken place in the past history of the earth.

To illustrate of what importance this might be, I might mention here a discovery we made during our voyage in the "Fram." By examining the salinity of the water and its temperature in the various depths, we found that the Polar sea is covered with a layer of comparatively fresh water, with a very low temperature, about the freezing point of water of that salinity (29.3 to 29.12 degrees Fahrenheit). When, however, we penetrated this layer to a depth of one hundred fathoms, we suddenly came on water with a greater salinity, and the temperature of which would be as much as 32.9 degrees, and even 33.44 degrees, Fahrenheit. This is much warmer than we should expect the water to be in the frozen North. At a greater depth the water varied somewhat, but remained about the same to a depth of from 220 to 270 fathoms, after which it sank slowly with the depth, though without sinking to the cold temperature of the surface water. It did not, as a rule, sink below 30.65 degrees, which temperature we found at a depth of about 1,600 fathoms. Near the bottom it again rose quite slowly, I think probably on account of the internal heat of the earth. These conditions may seem somewhat astonishing, seeing that the depths of the north Atlantic Ocean north of Scotland, the Faroe Islands, and Iceland are filled with icy-cold water, the temperature of which is about 29.3 degrees Fahrenheit. The depths of the sea in the South are consequently colder than you find them near the Pole. The reason is evidently that the warm salt water from the surface of the Atlantic Ocean is carried northwards by the Gulf Stream into the Polar sea, where it, however, meets the fresher and