As the Gulf Stream is of so great importance to Northern Europe in general, but especially to us Norwegians, it was not a mere accident that three separate expeditions left Norway in the same year, 1910 -- Murray and Hjort's expedition in the Michael Sars, Amundsen's trial trip in the Fram, and Nansen's voyage in the gunboat Frithjof -- all with the object of investigating the conditions in the North Atlantic. The fact that on these three voyages observations were made approximately at the same time in different parts of the ocean increases their value in a great degree, since they can thus be directly compared; we are thus able to obtain, for instance, a reliable survey of the distribution of temperature and salinity, and to draw important conclusions as to the extent of the currents and the motion of the masses of water.
Amundsen's trial trip in the Fram and Nansen's voyage in the Frithjof were made with the special object of studying the Gulf Stream in the ocean to the west of the British Isles, and by the help of these investigations it is now possible to chart the current and the extent of the various volumes of water at different depths in this region at that time.
A series of stations taken within the same region during Murray and Hjort's expedition completes the survey, and provides valuable material for comparison.
After sailing from Norway over the North Sea, the Fram passed through the English Channel in June, 1910, and the first station was taken on June 20, to the south of Ireland, in lat. 50º 50' N. and long. 10º 15' W., after which thirteen stations were taken to the westward, to lat. 58º 16' N. and long. 17º 50' W., where the ship was on June 27. Her course then went in a northerly direction to lat. 57º 59' N. and long. 15º 8' W., from which point a section of eleven stations (Nos. 15 -- 25) was made straight across the Gulf Stream to the bank on the north of Scotland, in lat. 59º 88' N. and long. 4º 44' W. The voyage and the stations are represented in Fig. 2. Temperatures and samples of water were taken at all the twenty-four stations at the following depths: surface, 5, 10, 20, 30, 40, 50, 75, 100, 150, 200, 300, 400, and 500 metres (2.7, 5.4, 10.9, 16.3, 21.8, 27.2, 40.8, 54.5, 81.7, 109, 163.5, 218, and 272.5 fathoms) -- or less, where the depth was not so great.
The Fram's southerly section, from Station 1 to 13 (see Fig. 3) is divided into two parts at Station 10, on the Porcupine Bank, south-west of Ireland. The eastern part, between Stations 1 and 10, extends over to the bank south of Ireland, while the three stations of the western part lie in the deep sea west of the Porcupine Bank.
[Fig. 2 and caption: Fig. 2. -- The "Fram's" Route from June 20 to July 7, 1910 (given in an unbroken line -- the figures denote the stations).
The dotted line gives the Frithjof's route, and the squares give five of the Michael Sars's stations.]
In both parts of this section there are, as shown in Fig. 3, two great volumes of water, from the surface down to depths greater than 500 metres, which have salinities between 35.4 and 35.5 per mille. They have also comparatively high temperatures; the isotherm for 10º C. goes down to a depth of about 500 metres in both these parts.
It is obvious that both these comparatively salt and warm volumes of water belong to the Gulf Stream. The more westerly of them, at Stations 11 and 12, and in part 13, in the deep sea to the west of the Porcupine Bank, is probably in motion towards the north-east along the outside of this bank and then into Rockall Channel -- between Rockall Bank and the bank to the west of the
[Fig. 3 and caption: Fig. 3. -- Temperature and Salinity in the "Fram's" Southern Section, June, 1910.]