On the Botany Watershed. 81 



must have been running from the Long Swamp into the sea 

 near Bunnerong, we may safely conclude that the conserving 

 powers of the Botany watershed are seven times greater than 

 those of the Cataract, equal to those of the Warragamba, and 

 greater than those of any other catchment visited by the Water 

 Commission during its investigation. After writing in such 

 high praise of the Botany watershed, strange as it may appear, 

 the report of the Water Commission goes on to state : — " We 

 have come, after mature consideration, to the conclusion that 

 it (the Botany supply) can barely be made adequate to the 

 existing wants of Sydney, and cannot keep pace with the 

 demands of an increasing population ; that it should therefore 

 be abandoned for another scheme which we will describe in the 

 sequel." The scheme in the sequel is that which comprises the 

 Cataract and the ISTepean at the Pheasant's JSTest. This source, 

 in consequence of the non-absorbent nature of the watershed, 

 it being composed of sandstone rock without any sand to absorb 

 or conserve the rainfall, has, so I am informed by a gentleman 

 of high respectability, been so free from water in the dry season, 

 that he could walk across dry-footed. So much for the Cataract 

 and Nepean watershed in comparison with that of Botany. It 

 will be seen by the returns from the Grovernment Observatory 

 that the average annual rainfall during the ten years from 1859 

 to 1868 inclusive, amount, within a small fraction, to 50 inches. 

 It amounted to about the same in 1869. The greatest rainfall 

 in any one of those years was 82-81 inches=21,870,730 gallons 

 per diem on the catchment, and the lowest 23 '98 inches, equal 

 to 6,333,294 gallons per diem. I commence with the year 1859, 

 because the returns from that date were made by the late 

 Government Astronomer. I have great faith in those returns. 

 In the next place, I completed the pumping machinery at 

 Botany in the end of 1858. Since that period I have been 

 professionally and practically engaged, more or less, in and 

 about the Botany watershed. I have studied the rainfall closely 

 and believe the returns to be perfectly reliable. The returns 

 made previously to 1859 do not appear to have been kept or 

 supervised by any responsible oiEcial, or at any particular place ; 

 for this and other reasons I ignore them. The superficial area 

 of the Lachlan and Botany catchment, which would naturally 

 discharge its waters into the sea at Botany, is 4249 acres. It 

 will be found by calculation that 50 inches of rain falling upon 

 4249 acres during one year will amount to 4,819,959,375 gallons, 

 and this qiiantity divided by 365, shows that the quanity ot 

 water which has fallen upon this catchment alone averages for 

 every day throughout the last eleven years, 13,205,368 gallons. 

 Then we have, in addition, the Long Swamp catchmeat, which 

 contains a superficial area of 1224 acres, and now discharges 



