ScHAw. — Australasian Weather-charts and N.Z. Storms. 67 



sion is much more notable than over the land. This last 

 observation, if established, would seem to favour the view 

 that the inherent force of the storm is due to the vapour of 

 water drawn up from the sea, which gives out its latent heat 

 when condensed in the upper strata of the atmosphere. 



Occasionally the first appearance of one of these depres- 

 sions is near Tasmania. I have not yet found in the records 

 more than one case where it first appeared at New Zealand. 

 This leads one to suppose that there is some special nursery 

 for storms on the shores of Antarctica, whence one after 

 another is constantly being launched on their ocean voyage. 

 How far a storm can travel before it ceases to maintain 

 its rotary character is yet, I think, uncertain, but a few cases 

 are recorded where the same storm seems to have been traced 

 halfway round the globe. 



In this Southern Hemisphere circular storms seem to be 

 more regular and persistent than in the Northern Hemi- 

 sphere, which probably is due to the smaller interference of 

 land in this hemisphere. The trade winds and counter-trades 

 are more powerful in the Southern than in the Northern Hemi- 

 sphere. The whole air-circulation is freer and more active, 

 and probably this is the main cause of the displacement 

 northwards of the equatorial belt of calms. Cyclones are 

 generally now called "lows," because the barometer shows a 

 low pressure of the atmosphere towards the centre of a 

 cyclone circulation, and the anti-cyclones are called " highs " 

 for the contrary reason. 



Now, w^e have every reason for believing that when a 

 cyclone borders on an anti-cyclone the surplus air from the 

 anti-cyclone pours down into the cyclone, and yet that the 

 circulation within the anti-cyclone is screwing downwards and 

 that in the cyclone is screwing upwards from below. 



We conceive, therefore, that, as air-motion depends on 

 gravity (apart from the motion due to the rotation of the 

 earth), the altitude of the plane where the air leaves the anti- 

 cyclone must be above the level of the plane where it enters 

 the cyclone. The latter appears to be at the level of the 

 earth's surface, and for an unknown height above it. Evi- 

 dently, if the cyclone is not filled up, and so quenched, the 

 air pouring in must escape upwards and outwards, and this 

 we believe it does, while the anti-cyclone is replenished by 

 air pouring in from above. Now, if the level of the atmo- 

 sphere above the anti-cyclone be above the average level of 

 the atmosphere, what force causes the surrounding air to rise 

 up and flow down into it ? To this I can find no answer in 

 books, although some German meteorologists attribute it to 

 the rotation of the earth. Hence it appears possible that 

 really the true height of the column of air near the 35th 



