THE PROSPECT AND KENNY HILL SCHEMES, 269. 
Francisco has 34 miles of large supply piping, whilst in London 
itself some of the mains have a pressure of over 200 feet head. 
Relief valves could be so fixed that in no portion of the supply 
pipe need the pressure under any contingency exceed a fixed 
ing a fracture to occur in the deeper undulations. To 
still further any chance of accident, an escape valve or sluice-gate 
might be fixed at the crossing of George’s River, so that, on any 
ure occurring nearer Sydney, any undue pressure from the 
closing of valves too suddenly might be obviated by allowing the 
water to escape into George’s River ; whilst, by using self-acting 
shut-off valves at the reservoirs, as adopted in the Dublin and 
Liverpool water-works, the flow into the piping from the reservoirs 
would be stopped in a few minutes after the occurrence of the 
fracture. Such ingenuity has been lately exercised in the inven- 
tion of stop-valves that they can be adjusted at a distance by, an 
electric wire, so that any chance of accident to a pipe conduit is 
now very remote. 
CoMMERCIAL AND ECONOMICAL QUALIFICATIONS. 
‘ . : - ‘ . . bl e; 
‘@ power always available by which, with but little trou 
he’can add considerably to his earnings Whereas if water was only 
available for domestic use, as supplied from Crown-street, “te 
gallons a head would be amply sufficient ; if it could be supp 
