Correspondence. Coolgardie Water Supply.

Abstract

The Author. they should be sufficient at any rate to begin with, for he had provided bypasses at each, so that any one could be thrown out of working without disturbing the daily supply. Moreover, the main was of wrought steel, and therefore not subject to the bursts which might be expected in a cast-iron main, and, in addition, the main was kept under as low a head as possible by regulating the outflowing discharge from Bakers Hill, West Northam, Bulla Bulling, and so on, instead of by means of valves at the respective receiving-reservoirs. When the demand increased largely, it would no doubt be advisable to increase correspondingly thecapacity of the service-reservoirs. The advantages of the circular form in service reservoirs, to which Dr. Deacon had drawn attention, were more or less generally acknowledged ; and where deemed advisable the circular form had been adopted in the service-and suctionreservoirs of the Coolgardie water-supply, though this was not stated in the Paper. The relative advantages of thick and of thin linings, also raised by Dr. Deacon, must always be one for argument ; and, personally, the Author preferred to expend %I at once, and another S1 after 20 years, rather than 51 15s., or even somewhat less, to begin with. The general statement,, referred to by Mr. Fitzmaurice, as to the improvement of mortar by the use of a proportion of loam in lieu of the same quantity of sand, was, of course, not based on the Author's opinion, but on the results obtained by Professor Sherman. The tests carried out for the Bulla Bulling reservoir confirmed that writer's results, and the Author would like in this connection to draw attention to the universal Indian practice of adding clay more or less burnt to pure limes. The clay was added in the presence of water, and unquestionably a stronger and more hydraulic mortar was produced than if the place of the clay had been taken by an equal quantity of sand. It was possible that similar good effects were produced by combination of clay with the free lime premnt in most Portland cements, but extreme care was necessary, as Mr. Hawksley had pointed out.