78 KEPOKT— 1891. 



by the cold south-west with dehiges of ram and a fall of the 

 thermometer often of 30'^ or 40° in an hour or two — and 

 the nor' westers of Canterbury, that, making allowance for 

 differences arising from local geographical peculiarities, it is 

 impossible to suppose otherwise than that the two have some 

 similarity of origin. The Australiaii wind blows however over 

 an arid continent, and thus increases rather than diminishes 

 its heat as it travels, and it meets with little or no obstruction 

 from high mountains calculated to drive it up into higher and 

 colder regions. On the other hand, the north-west wind of New 

 Zealand by the time it reaches our shores has crossed a wide 

 ocean and gathered from it both moisture and heat as it 

 travelled, and here it meets at a comparatively high latitude 

 with mountains 10,000ft. high, which are quite capable of 

 relieving it of its watery burden. The distance between Aus- 

 tralia and New Zealand is not so great as to lead us to doubt 

 the occasional identity of some of our cyclonic disturbances 

 with those prevailing over the water, and it must be remembered 

 we are directly in the line of travel ; and cyclones, though they 

 often fill up or diverge from their path, and otherwise conduct 

 themselves in a most unreliable manner, yet as a rule keep a 

 definite track and travel very far. Notwitbstanding all these 

 considerations, I do not argue for any identity, except a very 

 occasional one, between the hot winds of Australia, and New 

 Zealaiid. Our nor'westers for the most part have quite an 

 independent origin. 



5. On the Chcuxtctcristics of the Nor -tvesters of Canterbury, 



New Zealand. 



By John T. Meeson, B.A., Christchurch, New Zealand. 



1. Introduction and description of phenomena of nor'- 

 westers. 



2. Inquiry into the cause of their excessive heat. Com- 

 pression, the usual explanation, inadequate. True explana- 

 tion must take account of — (1) Original heat of equatorial 

 aerial current,- (2) heat given out when rain precipitated, 

 (3) different capacities of wet and dry air for holding heat, and 

 Dr. Hann's reasoning about the Swiss fuhn, (1) development 

 of heat on the left front of all cyclones ; why south-west winds 

 not hot though over high mountains. Original and acquired 

 heat of equatorial winds. Great effect of warm ocean-currents 

 in heating air above them. Conclusion re heat. 



