570 Transactions. — Chemistry and Physics. 



Art. LVII. — Further Light on the Circulation of the At- 

 mosphere in the Southern Hemisphere. 



By Major-General Schaw, C.B., E.E. 



[Read before the Wellington Philosophical Society, 14th March, 1899.] 



Plate LV. 



Having been favoured by J. L. Barthorp, Esq., an experienced 

 officer of the New Zealand Shipping Company's steamers 

 trading between England and New Zealand, with extracts 

 from the logs of twelve voyages between the Cape of Good 

 Hope and New Zealand, and of eleven voyages between New 

 Zealand and Cape Horn, during the years 1891 to 1898, 1 have 

 learned so many interesting facts from the ships' logs regard- 

 ing the circulation of the atmosphere in these southern oceans 

 that they appear to me worthy of record for general informa- 

 tion. 



These voyages have been made between the south latitudes 

 of 35° and 57°, those to Cape Horn being, of course, more 

 southerly than those from the Cape of Good Hope, though in 

 both a soixiewhat southerly course has been pursued, both to 

 shorten the distances by great-circle sailing and also to 

 benefit as far as possible by the usual westerly counter-trade 

 winds. It will be seen, however, by the logs that this latter 

 advantage is not always obtained, easterly winds being not 

 infrequently experienced. These easterly winds are some- 

 times experienced with a high barometer, indicating an anti- 

 cyclonic circulation very much farther south than has generally 

 been supposed to be the case. Strong indications indeed 

 are given that there is a second belt of anticyclones between 

 the latitudes of 60° and 70° south, in addition to the well- 

 known belt of anticyclones usually lying between the latitudes 

 of 20° and 40° south, and that between these two anticyclonic 

 belts cyclones move eastwards, their northern parts giving 

 the westerly strong winds usually felt ; but occasionally, as 

 the ship goes far south and the cyclone travels northwards, 

 the southerly part of the circulation is felt, with low baro- 

 meter and east winds. 



The rate of eastward travel of these cyclones appears to 

 correspond generally with that of the steamers, averaging ten 

 to twelve knots an hour ; so that a vessel may voyage eastwards 

 for many days in the comparatively fine weather of the inter- 

 vals between the following cyclones, or in the stormy weather 

 within one of them ; but occasionally the cyclones travel much 



