OCEANOGRAPHY 407 



the shore party on the Barrier. Neither on this trip nor on the 

 Fram's subsequent voyage to Buenos Aires were any investigations 

 worth mentioning made, as time was too short; but in June, 1911, 

 Captain Nilsen took the Fram on a cruise in the South Atlantic, 

 and made in all sixty valuable stations along two lines between 

 South America and Africa. 



An exhaustive working out of the very considerable material 

 collected on these voyages has not yet been possible. We shall 

 here only attempt to set forth the most conspicuous results shown 

 by a preliminary examination. 



BeaiJes the meteorological observations and the collection of 

 plankton — in fine silk tow-nets — the investigations consisted of 

 taking temperatures and samples of water at different depths. 

 The temperatures below the surface were ascertained by the best 

 modern reversing thermometers (Richter's); these thermometers 

 are capable of giving the temperature to within a few hundredths 

 of a degree at any depth. Samples of water were taken for the 

 most part with Ekman's reversing water-sampler; it consists of a 

 brass tube, with a valve at each end. When it is lowered the 

 valves are open, so that the water passes freely through the tube. 

 When the apparatus has reached the depth from which a sample 

 is to be taken, a small slipping sinker is sent down along the line. 

 When the sinker strikes the sampler, it displaces a small pin, 

 which holds the brass tube in the position in which the valves 

 remain open. The tube then swings over, and this closes the 

 valves, so that the tube is filled with a hermetically enclosed sample 

 of water. These water samples were put into small bottles, which 

 were afterwards sent to Bergen, where the salinity of each sample 

 was determined. On the first cruise, in June and July, 1910, the 

 observations on board were carried out by Mr. Adolf Schroer, 

 besides the permanent members of the expedition. The observa- 

 tions in the South Atlantic in the following year were for the most 

 part carried out by Lieutenant Gjertsen and Kutschin. 



The Atlantic Ocean is traversed by a series of main currents. 



