Investigations in the South Atlantic, June to August, 1911.

In the South Atlantic we have the southward Brazil Current on the American side, and the northward Benguela Current on the African side.  In the southern part of the ocean there is a wide current flowing from west to east in the west wind belt.  And in its northern part, immediately south of the Equator, the South Equatorial Current flows from east to west.  We have thus in the South Atlantic a vast circle of currents, with a motion contrary to that of the hands of a clock.  The Fram expedition has now made two full sections across the central part of the South Atlantic; these sections take in both the Brazil Current and the Benguela Current, and they lie between the eastward current on the south and the westward current on the north.  This is the first time that such complete sections have been obtained between South America and Africa in this part of the ocean.  And no doubt a larger number of stations were taken on the Fram’s voyage than have been taken —­ with the same amount of detail —­ in the whole South Atlantic by all previous expeditions put together.

When the Fram left Buenos Aires in June, 1911, the expedition went eastward through the Brazil Current.  The first station was taken in lat. 36deg. 18’ S. and long. 43deg. 15’ W.; this was on June 17.  Her course was then north-east or east until Station 32 in lat. 20deg. 30’ S. and long. 8deg. 10’ E.; this station lay in the Benguela Current, about 800 miles from the coast of Africa, and it was taken on July 22.  From there she went in a gentle curve

[Fig. 5 and caption]

past St. Helena and Trinidad back to America.  The last station (No. 60) was taken on August 19 in the Brazil Current in lat. 24deg. 39’ S. and about long. 40deg.  W.; this station lay about 200 miles south-east of Rio de Janeiro.

There was an average distance of 100 nautical miles between one station and the next.  At nearly all the stations investigations were made at the following depths:  surface, 5, 10, 25, 50, 100, 150, 200, 250, 300, 400, 500, 750, and 1,000 metres (2.7, 5.4, 13.6, 27.2, 54.5, 81.7, 109, 136.2, 163.5, 218, 272.5, and 545 fathoms).  At one or two of the stations observations were also taken at 1,500 and 2,000 metres (817.5 and 1,090 fathoms).

The investigations were thus carried out from about the middle of July to the middle of August, in that part of the southern winter which corresponds to the period between the middle of

[Fig. 6]

Fig. 6. —­ Currents in the South Atlantic (June —­ August, 1911).

December and the middle of February in the northern hemisphere We must first see what the conditions were on the surface in those regions in the middle of the winter of 1911.