198 The Rainfall of Victoria. 



find it only reaches to about half the annual evapora- 

 tion, which, according to Professor Neumayer's determinations 

 and observations since made at the Observatory, amounts to 

 about forty-five inches per annum. The largest amount of 

 this evaporation, of course, takes place dming our spring and 

 summer months, with our strong dry winds ; in winter the 

 rainfall exceeds the evaporation by a considerable amount. 



An opinion has often been expressed, that there is a kind 

 of periodicity of seasons in Australia, that dry and wet years 

 recur at intervals, which, if our observations extended back 

 far enough, would be found to be in some degree regular. I 

 think it within the bounds of possibility, that by a long and 

 systematic record of the rainfall over the Australian conti- 

 nent, that some rough law would be deduced by which the 

 recurrence of dry or wet years at stated intervals might be 

 looked upon as probable. A glance over the diagram 

 of rainfall in Melboin^ne for tlie last twenty-six years, 

 does not, however,, give us much foundation for such 

 an hypothesis — the missing years come in at an awk- 

 ward period — that is immediately after the abnormal 

 rains of 1849 — a few more years record subsequent to 

 our heavy fall of. 1863, are also required, when it would be 

 seen if any similarity existed in the curves immediately 

 following these very large defiections. Professor Newmayer, 

 in a very interesting and valuable essay, in the Catalogue of 

 the Yictorian Exhibition, " On the Climatology of Victoria, 

 stPutes that the average rainfall from 1855 to 1860 difiered 

 but little from the average rainfall for any six consecutive 

 years, from 1840 to 1848, excluding the abnormal rainfall 

 of 1849 ;" but our rainfall of 36 "43 inches in 1863, again 

 thrusts up the curve high above the average, showing that 

 that of 1849 was not a singular instance, and ought not to 

 be excluded from the means. 



An extended knowledge of our rainfall and evaporation I 

 feel sure would teach us much that might be done to 

 mitigate the disastrous consequences of so inadequate a 

 rainfall as we have just sufiered from. And above all, would 

 point to the necessity of a large and general system of stor- 

 age. The increased evaporation we are subject to indicates 

 that the mere collecting the water in reservoirs is not the 

 only consideration. The ratio of evaporation to the bulk 

 increases with the surface- — the reservoirs should rather be 

 deep than of large surfaces. The greatest evaporation takes 

 place during high, and especially high and dry winds — the 



