BOTTOM WATERS 135 



the settling of sediment particles, perhaps even re- 

 moving them after sedimentation, by what may con- 

 veniently be called "bottom erosion." 



The importance of these different questions was not 

 ignored in planning the Swedish Deep-Sea Expedition. 

 Thus, by means of current meters of special construc- 

 tion we had hoped to attack the problem of water move- 

 ments in the immediate vicinity of the ocean floor. 

 Preliminary attempts made in Swedish fjords before 

 the cruise had given rise to hopes that the bottom 

 currents, previously inaccessible to direct measure- 

 ments, could in fact be observed. Unfortunately the 

 time allowed us, both for preparing and carrying out 

 the cruise, was so short that this point had perforce 

 to be struck off our program. There remained, however, 

 another task more easily solved, which was to secure 

 water samples at well defined heights close to the bot- 

 tom itself without disturbing the sediment layer. This 

 aim was realized by a special technique of F. Koczy 

 which made it possible to get perfectly undisturbed 

 water samples at 3, 6, 10, 15, etc. meters above the 

 bottom.^ Not only could the chemical properties of 

 this near-bottom water be studied but also, by means of 

 a method developed by N. G. Jerlov, optician and 

 hydrographer of the expedition, the samples could be 

 examined for their content of suspended particles.- 

 The results are so important that I consider their in- 

 clusion here justified. 



The technique of water sampling may be clarified 



