160 METEOROLOGICAL PEEIODICITT. 



It will he seen that tlie Brisbane rain curve follows Sydney 

 very well ; it is below the average in 1859, above it for the two 

 years 1860-61, very low in 1862, high again in 1863-4, A^ery low 

 in our memorable 1865, and so on, running to maxima in 1870 

 and 1873, like the rain curve at Sydney. Melbourne is some- 

 times with Sydney, as in 1862, 1865, 1868, and 1870, when 

 droughts or heavy rains involved the whole eastern coasts ; but 

 it often accords with the Adelaide curve, to which I wish to draw 

 your particular attention, as it bears strongly on the opinions 

 expressed in this paper. {Diagram 1). 



The Adelaide curve, if inverted, agrees very closely with that 

 for Sydney, or, in other words, their rain seasons are the 023posite 

 of ours ; and when the dry seasons prevail here, the rain precipi- 

 tation, as I have before stated, is pushed southward, and recorded 

 in Adelaide, and often in Melbourne. From 1840 to 1859 this 

 fact is most striking, and, excepting 1854, 1864, and 1869, when, 

 as before stated, droughts seemed to envelope the whole of 

 Australia, we have a very marked agreement. For the first 

 nineteen years, seventeen are the reverse of Sydney, two agree 

 with it ; for the second period, eight out of fourteen are the 

 reverse of Sydney, and the others indifferent ; so that, twenty- 

 five years out of thirty-three, the rain curve at Adelaide is the 

 reverse of Sydney. At Melbourne these phenomena are not so 

 marked ; but in many cases the salne may be observed, notably 

 of our driest year. 1849 ; it was at Melbourne the wettest on 

 record. 



The remarks just made form a very good illustration of what I 

 have to state presently, viz., that the same cause, even a distant 

 one, will not produce the same effects on different portions of the 

 earth's surface. The force that brings us a drought usually 

 carries rain in abundance to South Australia. 



Let us now take the years in series, as they are arranged in 

 the diagrams, only remarking that the year 1783 to 1787 are with 

 us pre-historic : — 



1802. A medium year, but there is little information. 



1821. Moderate rain in July ; heavy rain and floods in Sep- 



tember. 



1840. Moderate rains ; heavy in July and September. 



1859. Heavy rain in January and February ; rain in July ; very 

 heavy and flood in September. 



1803. Early part, very dry ; latter part, wet and favourable. 



1822. Early part, very dry ; abundant rain in February ; latter 



part, wet. 



1841. February, dry ; terrific rain in April 29 ; abundant rains 



latter part. 



