Opening Address. 



"When the report on the water supply was drawn up the Com- 

 missioners had no means of determining the rainfall towards the 

 sources of the Nepean, but they assumed that it would not be 

 less than in Sydney, giving at the same time reasons for believing 

 that it might be greater. After an abortive attempt to establish 

 a rain gauge near the head of the Cordeaux, in the beginning of 

 last year, I succeeded in starting one in that locality in July. I 

 now give the results for ten months, along with the returns from 

 the gauge at the University, and it will thus be seen that a great 

 deal more rain falls on the head of the Cordeaux than at 

 Sydney. 



E.AIN IN Inches. 



1870. 



ITniversity. 

 2-90 

 2-57 

 1-41 

 5-14. 

 6-62 

 9-00 



4-93 



5-28 



8-24 



12-50 



Cordeaux. 



July 4-10 



August 293 



September 2-84 



October 14-62 



November 13-92 



December 11-78 



1871. 



January 11-37 



February 12-72 



March 818 



April 13-74 



The consideration of water supply and rainfall leads, by an 

 easy transition, to the general meteorology of the colony, and to 

 the valuable paper thereupon contributed by Mr. Russell to the 

 recently published volume on the Industrial Progress of New 

 South "Wales. Mr. E-ussell there shows (and I believe he is the 

 first to do so) that there are distinct indications of a period of 

 nineteen years in the rainfall of Sydney. I have carefully 

 examined his diagram along with the scanty notices found in 

 books and newspapers anterior to the regular record of rainfall, 

 most of these being quoted by Mr. Jevons in his paper on the 

 climate of Australia, and some being noted by myself while 

 searching for data for my paper on the " History of the Water 

 Supply of Sydney." TTsing all the facts available, I have con- 

 structed a number of tables, arranging groups of similar years 

 under the headings " wet years," " medium years " (being those 

 where the rainfall differs little from the mean) ; " medium dry 

 years " (being those where the rainfall is under the mean, but 

 not much) ; and " dry years," A mark of interrogation implies 



