RIVERS OP NEW SOUTH WALES. 403 



occasional strata of inferior holding capacity, Ave have still a 

 storage capacity equal to a reservoir 5,262 acres in extent and 

 twenty-two feet deep. The area here mentioned is that given in 

 one part of ^Ir. Clark's Report on the Water Supply of Sydney ; 

 but at another place in the same repoi-t he gives the Botany 

 catchment as .5.8 square miles, or 3,712 aci'es. Assuming only 

 the latter area as representing the storage, we find that with the 

 depth stated above, the storage capacity of the Botany basin is 

 over twenty-two thousand millions of gallons, or more than three 

 times the available storage capacity of the Prospect Reservoir, 

 Taking as tlie total catchment the larger area mentioned by Mr. 

 Clarke, namely, 5,262 acres, we lind that more than three inches 

 of rain actually stored from that extent of surface would be 

 sufficient to give a uniform supply of one million gallons per day 

 for a year. So long as the total demands of Sydney did not 

 exceed the quantity contributed to the sands by the rainfall, the 

 supply at Botany appeared inexhaustible. The case is similar in 

 regard to our undei-ground supplies in the western districts. Just 

 as the Botany storage atiorded a uniform supply, within certain 

 limits, to Sydney, or as Lough Neagh in Ireland acts in equalising 

 the flow in the River Bann, or, on an immense scale, as the great 

 lakes of North America give a comparatively uniform flow in the 

 River St. Lawrence, so the deposits of drift under our table-lands 

 and under our alluvial plains, act in affording a steady supply in 

 the underground streams. 



In India irrigation from wells has been carried on from time 

 immemorial, and throughout the Bengal Presidency wells are now 

 to be seen in use for this purpose in thousands. I have no doubt 

 that there are many places in New South Wales where wells 

 could be so used to great advantage ; but, with the exception of 

 tliose in Chinamen's gardens, I have seen only two wells used for 

 irrigation in this colony, altliough my opportunities for observation 

 have been numerous and widespread. In the districts of the 

 Murrumbidgee, the Macquarie, and the Namoi, I believe there are 

 places where the underground supplies can be utilised in this 

 manner ; but I think it improbable that either the quantity or 

 quality of the water obtained from Avells or borings at a distance 

 of more than a hundred miles from the hills will warrant expendi- 

 ture for irrigation. 



Deep underground supplies of water frequently flow in narrow 

 channels ; but tliey are more frequently met with in widespread 

 deposits of drift. A prominent instance of the latter class of 

 cases is that furuislied by the Punjab, and the Noi'th West Pi'O- 

 vinces in India Tliere, over A-ery extensive ai-eas, so regular is 

 the slope of the underground streams as well as the surface of the 

 ground, that the landliolders can almost always estimate to within 

 a very few feet, the depth at which a good supply of water can be 



