ANTARCTIC EXPLORATION — THE DUTY OP AUSTRALIA. 415 



must be peculiar and extreme. All round the Antarctic Circle we 

 have a low mean l)arometor, a moist atmosphere, and a perpetual 

 grand cyclonic air movement from east to west. The co-operation 

 of these three conditions permanently and in an extreme degree 

 of development, without the circle, must surely produce within 

 its vortex an exceptional meteorological state which ouglit to be 

 studied, for its great scale and its location so near to Australia 

 must enable it to dominate our Australian climate. 



That the south polar winters must be milder than the polar 

 seems to be likely. Many estimated that the diflerence between 

 them was in favour of the Antarctic, in the same degree that the 

 English winter is milder and better than the Canadian. 



Another important branch of science which requires attention 

 is that which deals with the earth's magnetism in its three 

 elements of variation, dip, and intensity, and with their daily, 

 yearly, and secular variations. 



The exact position of the magnetic pole will be again determined 

 if possible, as also the foci of magnetic intensity. 



Connected with this subject is that of the phenomenon of 

 Auroras, the nature of which has been investigated recently by Dr. 

 Sophus Tromholt and others with some degree of success. Tromholt 

 tells us that the Aurora Borealis, with its crown of many lights, 

 encircles the North Pole obliquely, that it has its lower edge 

 suspended above the earth's surface at a height of from tifty to 

 one hundred miles ; and that it changes its latitude of maximum 

 intensity four times every year. The far-reaching, though subtle 

 nature of the influence which characterises this phenomenon is 

 shown by the fact that two years since when an Aurora was 

 observad at Hobart, the telegraph apparatus was galvanised into 

 such a state of activity that the wires were rendered simultaneously 

 useless for their normal work all the way from Hobart to Hong 

 Kong. 



Tromholt and others believe that weather changes and auroral 

 movements are in some way related. If this is so, and the eleven 

 year period of auroral activity be correlated with our Australian 

 cycles of drought and abundance, the Aurora will, in Australia, 

 have acquired a new interest. We ought therefore to ascertain 

 whether the Aurora of the Southern Hemisphere has its period as 

 that of the North has been shown to have, and this can be done 

 only by observations in higli southern latitudes. In this periodicity 

 of the Southern Auroras, we have the last problem to which I 

 would call your attention. If its determination would give us a 

 key to the periodic changes in the Australian seasons, which would 

 enable us to forecast, even partially, their mutations for, say but 

 a season in advance, it would give us in conducting those great 



