76 DISCOVERY REPORTS 



Australian Continent, sending a branch towards the north along the coast of Western 

 Australia. Kriimmel in 191 1 (p. 675) regarded the West Australian current as very 

 similar to the Benguela current off the west coast of Africa. Recent work by Michaelis 

 (1923), Schott (1933) and the Hydrographic Office (Australia Pilot, v, 1934) shows, 

 however, that there is no such well-marked northward current. The movements in the 

 coastal region are now known to be weak and variable, with a tendency towards the 

 south in winter and towards the north in summer. Strong currents of 30-40 miles a day 

 have sometimes been recorded, but they are not permanent, and the temperature charts 

 given by Schott (1933, pi. 28) suggest that there is no great transport of water towards the 

 north or south. The temperature charts indicate that the predominating movement 

 during the year, especially very near to the coast, is towards the south. 



We made a series of observations across the coastal region between the northern end 

 of section 9 and Fremantle on May 9-10. The temperature and salinity distribution in 

 the first 1000 m. is given in Figs. 17-18. The slope of the isotherms and isohalines 

 shows that there is a southward movement throughout the section, and the lower salinity 

 and higher temperature of the coastal water indicate that it is of tropical origin. At 

 St. 875, roughly 100 miles from the coast, the current was so strong that some difficulty 

 was experienced in handling the ship so as to keep the deep hoists vertical. 



The temperature and salinity distribution in the region south-west of Cape Leeuwin 

 shows that a continuous belt of subtropical water extends across the area, just as it does 

 south-west of the Cape of Good Hope, and the West Wind Drift does not divide on the 

 south-western extremity of the continent as many of the earlier charts have indicated. 

 The current charts given by Michaelis (1923), with modifications suggested by the 

 charts of Schott (1933, pi. 28), seem to give the best agreement with the temperature 

 and salinity distributions. The water in the southern part of the subtropical zone 

 flows approximately eastwards, bending slightly northwards in 90-1 io°E, and then 

 southwards as it approaches the region south of Australia. Farther north the current 

 charts show that the subtropical water is carried northwards in the eastern part of the 

 ocean, principally in summer, to form an anticyclonic circulation such as that which is 

 well known in the subtropical part of the South Atlantic Ocean. The temperature and 

 salinity charts given by Moller (1929, figs. 17, 21) and Schott (1934) give some support 

 for this representation, but the small advance of the isotherms towards the north suggests 

 that the northward movement is probably exaggerated. Willimzik (1929, p. 15) states 

 that in consequence of the northward movement the northern boundary of the West 

 Wind Drift is in winter carried northwards from 36 S in 30-55 E to 25 S in the eastern 

 part of the ocean ; but the temperature and salinity charts, especially the latter, give a 

 clear indication that the current does not follow this path. The convergence shown in 

 Moller's charts must therefore not be confused with the boundary between the sub- 

 Antarctic and subtropical waters, which lies much farther south, and it may possibly 

 show the southern limit of tropical water (Deacon, 1933, pp. 216-17). 



When the current flows towards the north along the west coast of Australia it is a 

 subtropical current, and it appears to have its origin largely in a movement from the 



