„6 DISCOVERY REPORTS 



140 W, the bottom current bends back to the south. The deflection of the current is in 

 each instance in agreement with the effect of a shallowing and deepening of the ocean 

 on the easterly current as deduced theoretically by Ekman (1928). The same observations 

 also show that a small part of the bottom current turns back towards the west in the 

 neighbourhood of the continental slope, giving rise to a small cyclonic movement. The 

 bottom water adjacent to the ridge which closes the Ross Sea thus appears to flow 

 towards the west, and in section 14 the coldest bottom water is not found farthest south 

 but between 65 and 70 S. The cyclonic movement is, however, only small and weak 

 compared with that in the Atlantic-Antarctic basin. 



Farther east in the Pacific Ocean the temperature and salinity of the bottom current 

 go on increasing while the oxygen content decreases, and the bottom water in sections 

 16 and 17 (Plates XXXVI I-XL, XLII) still has the properties of the eastward current 

 from the Weddell Sea mixed with more warm deep water. A comparison of the 

 temperature and salinity of the bottom water in section 18, in 8o° W (Plates XLI, XLII), 

 with those of the bottom water in section 16, leads to the same conclusion. A com- 

 parison of the oxygen data shows, however, that the water in 8o° W is slightly richer 

 in oxygen. The difference is very small (only o-o-i cc. per litre), and it may be due to 

 a seasonal change in the properties of the current ; but the close proximity of the section 

 to the Atlantic Ocean and the fact that the difference is shown by both the 1932 and 

 1934 observations (Sts. 988-94, 972-4, and Sts. 1312, 1247-1245) suggests that it may 

 be due to a very small inflow of bottom water from the Scotia Sea. 



A comparison of the temperature distribution in sections 1 and 18 (Plates II, XLI) 

 across the eastern and western ends of the Drake Passage shows that the bottom water 

 is slightly colder at the Atlantic end ; the temperature gradient, particularly below a 

 depth of 3000 m., is sharper, and on the southern side of the passage the bottom water 

 is 0-3-0-4° C. colder than it is at the Pacific end. The water at the Atlantic end is also 

 slightly less saline and richer in oxygen (Plates II, XLI-XLII), and these properties, 

 together with the low temperature, show that it does not belong entirely to the current 

 which flows eastward round almost the whole of the continent, but partly to a westward 

 movement from the Scotia Sea. A closer investigation of the data will be needed 

 before the limit of the westward current can be determined exactly ; but it is clear from 

 the temperature chart constructed by Wiist (1933, pi. ii) that the current diminishes 

 rapidly in 55-70° W, and probably not more than a trace, very close to the continental 

 slope, flows farther west. The slightly higher oxygen content of the bottom water in 

 section 18 indicates that such a trace of Atlantic water reaches 80° W. 



A more careful examination of the data must also be made before it is possible to say 

 what happens to the final traces of water from the circumpolar bottom current ; part of 

 the current may continue towards the east through the Drake Passage above the colder 

 water which flows westwards from the Scotia Sea, but it is also possible that the whole 

 of the current bends towards the north in the eastern part of the Pacific Ocean 

 together with the highly saline deep current (p. 104). 



An examination of the properties of the bottom water such as that made in the 



