It is only forty years since the Challenger sailed on the first great exploration of the oceans.  Although during these forty years a quantity of oceanographical observations has been collected with a constant improvement of methods, it is, nevertheless, clear that our knowledge of the ocean is still only in the preliminary stage.  The ocean has an area twice as great as that of the dry land, and it occupies a space thirteen times as great as that occupied by the land above sea-level.  Apart from the great number of soundings for depth alone, the number of oceanographical stations —­ with a series of physical and biological observations at various depths —­ is very small in proportion to the vast masses of water; and there are still extensive regions of the ocean of the conditions of which we have only a suspicion, but no certain knowledge.  This applies also to the Atlantic Ocean, and especially to the South Atlantic.

Scientific exploration of the ocean has several objects.  It seeks to explain the conditions governing a great and important part of our earth, and to discover the laws that control the immense masses of water in the ocean.  It aims at acquiring a knowledge of its varied fauna and flora, and of the relations between this infinity of organisms and the medium in which they live.  These were the principal problems for the solution of which the voyage of the Challenger and other scientific expeditions were undertaken.  Maury’s leading object was to explain the conditions that are of practical importance to navigation; his investigations were, in the first instance, applied to utilitarian needs.

But the physical investigation of the ocean has yet another very important bearing.  The difference between a sea climate and a continental climate has long been understood; it has long been known that the sea has an equalizing effect on the temperature of the air, so that in countries lying near the sea there is not so great a difference between the heat of summer and the cold of winter as on continents far from the sea-coast.  It has also long been understood that the warm currents produce a comparatively mild climate in high latitudes, and that the cold currents coming from the Polar regions produce a low temperature.  It has been known for centuries that the northern arm of the Gulf Stream makes Northern Europe as habitable as it is, and that the Polar currents on the shores of Greenland and Labrador prevent any richer development of civilization in these regions.  But it is only recently that modern investigation of the ocean has begun to show the intimate interaction between sea and air; an interaction which makes it probable that we shall be able to forecast the main variations in climate from year to year, as soon as we have a sufficiently large material in the shape of soundings.

In order to provide new oceanographical material by modern methods, the plan of the Fram expedition included the making of a number of investigations in the Atlantic Ocean.  In June, 1910, the Fram went on a trial cruise in the North Atlantic to the west of the British Isles.  Altogether twenty-five stations were taken in this region during June and July before the Fram’s final departure from Norway.