for the year 1881. xxi 



The way the wind shifts tells us of this. So long as the 

 wind is north, the centre is to the west of us; if it shifts 

 from N. to N.W., as is most frequently the case here, the 

 centre passes to the south of us ; if it falls calm, with per- 

 haps clear sky and very low barometer, the centre passes 

 over us ; but if the wind backs from N. to N.E. and E., it 

 will pass to the north of us. 



More or less rain generally accompanies such occurrences, 

 but the quantity with us much depends on the magnitude 

 and depth of the cyclone, the rate of translation, whether 

 it is single or double, and also as regards our position with 

 reference to the centre. Much rain often comes in front of 

 a cyclone ; yet some of our heaviest floods have occurred in 

 the rear, and on the north or equatorial side of a large and 

 slowly moving cyclonic area. The amount and extent of 

 rainfall on our south coast also, I believe, depends a great 

 deal upon the way the advancing isobars are resisted, so to 

 speak, by the areas of higher pressure over the land ; and 

 heavy rains generally result if an area or part of an area 

 of low pressure protrudes abruptly into a resisting area of 

 higher pressure. 



There is no doubt that the majority of our cyclonic whirls 

 move from W. or S.W. easterly, many of them being de- 

 flected south clown along our coast, and perhaps south of 

 Tasmania. Some, however, pass inland to the north of 

 Victoria, and occasionally they may be found coming down 

 on us from a northerly direction, or from the south-east ; 

 these, however, are exceptional cases. New Zealand gets 

 weather warnings from Australia, and a storm reported off 

 Cape Borda arrives there in about three days. Dr. Hector 

 tells me that nearly every depression we report reaches New 

 Zealand, and can be foretold there two or three days before- 

 hand. 



One of the most important meteorological questions in 

 these colonies is that of the rainfall ; but although the ap- 

 proach and movement of storm centres along our coasts and 



