7 8 DISCOVERY REPORTS 



with a temperature of 18-19 C. and a salinity of 35-8 % , which appears to belong to 

 a movement towards the south-east from a region farther offshore in the Indian Ocean. 

 Between 35 50' and 37 S the water was colder (15-16 C), but it still had a salinity of 

 357 7oo and it: was P ro bably part of a current flowing towards the west from the region 

 south of Australia. South of 37 S there was a narrow stream of colder and less saline 

 water whose temperature and salinity, 12-14 C. and 34'9-35'4 °L suggest that it 

 probably belonged to an eastward drift in the southern part of the subtropical zone. 



South of Australia the current charts of Michaelis (1923) show that the eastward 

 movement extends roughly to 40 S in summer and as far north as a line from Cape 

 Leeuwin to Tasmania in winter. North of these limits the current has a tendency to 

 turn towards the north, and then, forming an anticyclonic movement centred in the 

 western part of the Great Bight, back towards the west. The coastal region is not, how- 

 ever, one with a strong current, and the direction of movement depends largely on the 

 prevailing wind. The current appears to set towards the east for the greater part of the 

 year, but under the influence of easterly winds which occur most frequently in November 

 to April, is reversed (Australian Pilots 1, p. 9; and 11, p. 27). The current through the 

 Bass Strait between Tasmania and Australia generally flows towards the east, but it 

 may be reversed by an easterly wind. 



Off the east coast of Australia there is a southward current of subtropical water, known 

 as the East Australian current, which resembles the Brazil current ; it starts as a tropical 

 current, a branch of the equatorial drift towards the west, which turns southwards as 

 it approaches the land. The principal winds off the coast are north-east in summer 

 and south-west in winter, but the current sets almost constantly towards the south. As 

 it flows southwards, into the region of westerly winds, it is gradually deflected to the 

 left like the southern part of the Brazil current. The most recent current chart (a 

 preliminary chart drawn by Merz, published by Wiist, 1929, fig. 10) shows that it is 

 all turned away to the east before it reaches the latitude of the Bass Strait, but our 

 observations in sections 11 and 12 (Plates XXII-XXVII) suggest that it flows farther 

 south. Both the surface and subsurface waters were found to be much warmer and more 

 saline off the east coast of Tasmania than off the west coast, and it seems most probable 

 that the difference is due partly to the continued southward movement of the East 

 Australian current, and also to the bending of the current from the Bass Strait towards 



the south. 



In the eastern half of the Tasman Sea, between Australia and New Zealand, the 

 current flows towards the north-east. Along the west coast of South Island it is mixed 

 with sub-Antarctic water, but most of the mixed water seems to escape towards the 

 east through Cook Strait, and west of North Island the temperature and salinity of the 

 water suggest that it has its origin in the subtropical current from the Bass Strait and 

 East Australian regions. According to Krummel (191 1, n, p. 7 11 ) the current bends 

 towards the east round North Cape, and then southwards past East Cape to join, in 

 the neighbourhood of the Chatham Islands, with the currents which flow eastwards from 

 the Cook Strait and round the southern end of South Island. In the southern summer, 



