80 On the Botany Waterslied. 



to show tlie amount of evaporation not being applicable to 

 large reservoirs, ought to have been treated as such by the 

 Water Commission, and their results should in no way have 

 influenced their calculations. If the Water Commission allowed 

 its judgment to be guided by the results of these observatory 

 experiments in India, and fixed an absolute loss at two-thirds 

 of the rainfall on the Botany watershed accordingly, it should 

 tell us what becomes of it, or where this large body of water 

 goes to. That which is absorbed by the sand can afterwards lose 

 nothing by evaporation until it comes to light again at a lower 

 level. It will descend into the sand, at most, as far as the rock, 

 then with an elevation in the watershed of 110 feet, and a 

 sandstone bottom with a declivity towards the south, the water 

 absorbed in the rainy season will percolate through the sand and 

 appear at Botany, or before it reaches there, some time or other. 

 It cannot be lost in such a watershed by absorption. If it were, 

 the accumulation in the earth of two-thirds of the rainfall of 

 past ages on the Botany watershed would be something fabulous. 

 We have a right to conclude that it reaches Botany in the dry 

 season of each year — that is, in the months of November, 

 December, January, and part of February — and keeps up that 

 continual and copious flow which surprises every beholder. 

 The Water Commission eulogises it in its report (page 18), in 

 the following words : — " As the Lachlan Swamp is about 110 

 feet above the sea, and the stream has a gradual slope (in about 

 five miles) to Botany, we have here an immense body of sand 

 to get saturated with water in time of rain, and to give out 

 this water slowly by percolation at the lower level. In our 

 investigation we have found no similar locality with an equal 

 power of conserving water. Tv hen we visited the extensive 

 swamps at the head of the Cataract River, in December, 1867, 

 we found them delivering less than half the water delivered at 

 the same time at Botany, although the drainage area was more 

 than double the extent ; and in 1868, the AVarragamba, with its 

 drainage area of more than 3000 square miles, was delivering 

 no more water than is usually supplied to Sydney from the 

 Botany stream." Now, if the members of the Water Com- 

 mission found the extensive swamps at the head of the Cataract 

 Eiver delivering less than half the water delivered at the same 

 time at Botany, although the drainage area was more than 

 double the extent, they must readily admit that the conserving 

 powers of the Botany catchment must be nearly, if not quite, 

 five times greater than those of the Cataract. Then, when it is 

 considered that at the time this observation was made, the head 

 waters of the Botany catchment were passing from the Lachlan 

 Swamp through the tunnel into Sydney at the rate of 1,200,000 

 gallons per day at the very least, and that a similar quantity 



