64 THE CLIMATE OF AUSTRALASIA 



rainfall appear to be very irregular. The rainfall 

 conditions for Sydney and Adelaide are less so, 

 although, as Russell has pointed out, they are 

 reversed (fig. 15). Years of heavy rainfall at 

 Sydney are years of light rainfall at Adelaide, 

 because Sydney has entirely a coastal rainfall, and 

 the Adelaide rainfall is mainly continental. This 

 fact explains the apparent caprice of the Mel- 

 bourne rainfall. Melbourne is intermediate 

 between the conditions of Sydney and Adelaide. 

 It receives some of the rains of the Australian 

 coastlands, while it shares the inland rains 

 which are the most powerful at Adelaide. If 

 we could separate the Melbourne rainfall into 

 its two distinct sources, we should probably 

 find that each of them would be represented 

 by regular curves ; but when combined the 

 results are capricious and unintelligible. 

 Looked at from this point of view, instead of 

 the rainfall statistics of Adelaide and Sydney 

 being fatal to a belief in a periodic system, 

 they flash into agreement, and those of Mel- 

 bourne are not inconsistent with the existence 

 of the great cycle. 



CHAPTER III. THE WEATHER CYCLE 

 IR'REGULAR IN LENGTH. 



There is another essential precaution to be 

 observed in search for a weather cycle. We 



