METEOEOLOGICAL PERIODICITY. 169 



Or, taking another line o£ the nineteen years series : — 



1797. January was very hot, March and April wet, and from 



May to the end of the year very dry. 

 1854. January, hot ; March, April, and June wet ; all the rest 



of the year very dry. Of the intermediate year, 1816, 



though there was, like these, a dry spring, there were 



very high floods, May 30 and June 20, and heavy rain in 



November. 

 While 1873, the fifty- seventh year from 1816, there were floods 



on the 5th and 18th June, almost returning to the day, 



and there was a dry spring. 



It is needless to multiply instances — pages might be filled had 

 we the time ; those which have been given are sufficient to estab- 

 lish a very strong probability in favour of this law. To others, 

 who have not investigated the facts, it may come with less force 

 than it does to me ; but those who are interested will shortly 

 have before them more complete information about the meteor- 

 ology of New South Wales for past years than it is possible to 

 give in this paper. 



Of the probable cause or causes which produce the effects we 

 have been considering, volumes might be written ; but space 

 requires me to condense into a few pages my views on this sub- 

 ject ; and, at the risk of leaving out some points of importance, 

 I will try to be as brief as possible. 



And first, allow me to say, that I still hold the opinion (which 

 was expressed in my " Notes on the Climate of New South 

 A¥ales " in 1870), viz., that it is wet or dry with us, just as the 

 trade winds are weaker or stronger. In other words, that when 

 from some cause the trade winds and N.W. monsoon set to the 

 southward with more force than usual, we have a preponderance 

 of northerly and north-westerly winds, and, of course, dry 

 weather, because the region of rain precipitation is on the mar- 

 gin of the trades ; and if this is pushed to the south of us, we 

 have dry winds here, and an extra rainfall on the south coast ; 

 and if the trade wind is weaker we are in the rain region and 

 have abundance of it ; and I have by no means given up the 

 opinion expressed at the same time, that the moon has a great 

 influence upon our weather. Every year only adds to the facts 

 which, to me at least, prove lunar influence on the weather ; and 

 had I time I should be glad to introduce here many of them from 

 my own observation which go to prove the moon's influence in 

 forming and in dissipating clouds, besides many collateral facta 

 proving her influence on the atmosphere, volcanoes, &c., but these 

 must be left for another opportunity. 



Since 1870 many facts bearing upon the interdependence of 

 the parts of the solar system have been brought to light, more 

 especially by the study of meteoric astronomy, which seem to 



