34 UNDERGROUND WATERS. 



decreased flow. After explaining in detail the injuries 

 to the bores through closing the valves, he remarks, " It 

 is quite possible, indeed very probable, that this (closing 

 down the valves) is the true reason why many of the flows 

 are diminishing." 



In the case of the Longreach town bore, Central 

 Queensland, I found on examining it, before beginning 

 the reticulation works of the town from the artesian bore, 

 the water was flowing almost as much outside the bore 

 casing as within it. Evidently some injury had been done 

 previously to this bore, probably through a shock from 

 water ram. The depth to the water-bearing bed is about 

 2400ft. ; the pressure of the water at the surface was about 

 75lbs. to 901bs. per square inch. The shock from water 

 ram which occurs when a bore is valved down, would be 

 a heavy one, and most probably suifi.cient to burst the 

 casing, and cause a diminution of the flow inside the bore 

 casing, and also make the water leak away underground. 

 It is well known that if a valve in a line of system or water 

 pipes be suddenly closed while the water is flowing freely 

 under pressure, such sudden closing of the valve will pro- 

 duce a strain upon the pipes far greater that that due to 

 the static head of water. I have known cases where town 

 water pipes were burst by the closing of the street valve, 

 and water ram caused by such closing. The bursts occurred 

 so frequently that the matter was investigated by me, 

 and it was found the bursts of pipes were caused by closing 

 a hydrant valve from time to time, and the pipes were also 

 found weak through corrosion. In the case of an artesian 

 bore well, the bursting of the casing pipe, from water ram 

 and corrosion of the pipe, would show by water coming 

 up outside the casing, or the water would find an escape 

 underground into some porous beds of rock, or some open- 

 ings in the shale, or some permeable rock through which 

 the bore has passed. 



Waste Caused by Restriction of Flow. 



From inquiries I have made respecting some of the 

 artesian bores of Queensland I consider the facts and 

 conditions point strongly in the direction of the conclusion 

 that the diminished flow of artesian wells is mostly caused 

 by the closing down of the valves, and thereby bursting 



