148 C. W. DARLEY. 



duty of this class being to store at least one to two days supply 

 of water close at hand and immediately available in case of a 

 sudden demand for extinguishing fires, and to maintain an uni- 

 formity in the supply. It is to this class of Reservoir I propose 

 to invite your attention this evening. 



Where a town is supplied by gravitation from a distant Storage 

 Reservoir it may not at first sight be apparent why a "Service" 

 Reservoir is necessary as well, but when it is borne in mind that 

 at least one half the whole daily consumption is used within eight 

 hours, or, in other words, that the maximum hourly consumption 

 of a town is more than double the average hourly consumption, 

 it becomes clear that unless a very large gravitation main is laid, 

 the supply will be unduly restricted when the greatest demand 

 exists, therefore as a matter of economy alone, a Service or dis- 

 tributing Reservoir within the town becomes a necessity, for by 

 its adoption, the size of the gravitation main can be reduced to a 

 capacity sufficient to carry the maximum average daily consump- 

 tion with an uniform discharge throughout the whole twenty four 

 hours. 



Again, Service Reservoirs are almost essential in towns supplied 

 by pumping, and their use in this Colony has in the generality of 

 cases to be resorted to, for out of fifteen towns where works have 

 been carried out by the Government, it has only been possible to 

 supply one town wholly, and one partially by gravitation. 



I wish you to note that I qualified the above statement by 

 saying "almost essential" as it is not absolutely necessary to con- 

 struct a Service Reservoir when pumping is resorted to, many 

 towns in other parts of the world being supplied either through 

 stand pipes or by direct pumping into the main, but as either of 

 these systems renders it necessary to keep the pumps constantly 

 at work through the twenty four hours to avoid an intermittent 

 supply, it must be at once admitted that when a Reservoir can be 

 constructed with sufficient altitude, no reasonable cost should be 

 spared in providing one. Modern steam pumping appliances are 



