LXXXII PRESIDENTIAL ADDRESS 



The subject of the ocean currents off the Australian coast has 

 been specially discussed in an able paper by Mr. G. H. Halligan.^ 

 Those interested are also referred to the carefully prepared account 

 of the East Australian current^ called by him the Notonektian 

 current, by Mr. Charles Hedley.^ Professor J. W. Gregory, late 

 of Melbourne University, has also written on the climate of Aus- 

 tralasia in reference to its control by the Southern Ocean. 3 



The accompanying map, the most complete and reliable to 

 which I have access, is after Mr. G. H. Halligan (Fig. 6). 



It will be noticed that on the map of the world showing ocean 

 currents, the cold currents of the Southern Hemisphere are chiefly 

 on the west coasts of the great continents, and the warm currents 

 on the east coasts. These currents depend for their direction 

 chiefly on the prevalent winds. The roaring forties tend to drive 

 the cold water of the Antarctic up the west coasts. To this cause 

 is due the Peruvian current, the Benguelan current, and the 

 Western Australian or Humboldt current. Warm water flows 

 down the east coasts of South America, South Africa, and East 

 Australia, recurving from the east to west current set up by the 

 trade winds. 



Mr. C. Napier Bell, of New Zealand, called the attention of 

 this society ^ to the very interesting fact that the temperature on 

 the west side of New Zealand was quite an exception to the rule, 

 for it is no less than 8 deg. to 10 deg. F. higher than that on 

 the east coast. This is due to a recurving of the East Australian 

 current, the current flowing eastwards from Gabo Island until it 

 strikes New Zealand, when it is deflected northwards, thus raising 

 the temperature along all the west coast of New Zealand. The 

 current of Bass Strait in winter, when the centre of the high 

 pressure belt is well north of the southern coasts of Australia, 

 and consequently the westerly winds control the strait, sets strongly 

 from W. to E.; but in summer, when the high pressure belt has 

 moved down to the latitude of Bass Strait, and so the westerly 

 winds are displaced southwards, the easterly current becomes very 

 sluggish. In the Great Australian Bight the current is normally 

 easterly. On the west coast of Australia the current sets north, 

 and is a relatively cold current. The currents along the north 

 coast of Australia are controlled by the trade winds, and are 

 derived from the south equatorial current, which is probably some- 

 what checked or driven on shore in summer by the N.-W. monsoon. 



Past Climatic Chamjes. — A study of these in detail would 

 easily supply material for several addresses, and indeed they have 



' Proc. Linn. Soc. N. S. Wales, New Series, Vol. xxxi., PI. lii. 

 = Ihid. N. S. Wales, New,Series, Vol. xxxv., Pt. 1, pp. 9-21. 



' The climate of Australasia in reference to its control by the Southern Ocean. By J. W. 

 Gregory, L>.Sc., F.R.S., Melbourne, Whitcome and Tombs Limited. 

 * Rep. Austr. Assoc. Adv. Sci., Christchurch, N.Z. 



