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A kindred work of scarcely less importance than the capture, storage, and conveyance of water in adequate quantities for the people, will be the reorganization later on, of the system of its distribution among the people. The streets and houses of the town will have to be divided into three parallel level zones or belts: high-level, middle-level, and low-level, and each zone will have to be fed from its own central main. Much of the present distributing apparatus may be utilized and expense kept down, but a large proportion of new mains will be required, if efficiency is to be attained and waste prevented. I do not know that any outlay under this head is chargeable to the Tytam water-works, but that it is a service which will before long-with a large supply in prospect-require the close atten- tion of the Government is indubitable. The matter, however, is too large a one to be dealt with here, and must form the subject of a special report which will shortly be submitted.
PROGRESS OF THE WORKS.
Dam.-The design for the dam shows a wide pedestal or table of cement concrete twenty feet high, stretching across the bottom of the gorge and going down deep into the rock in search of good foundations. Upon this pedestal a masonry and cement concrete wall over sixty feet thick at its base, will be built to a height of ninety feet, tapering upward as it rises, and divided into nine successive steps or stories each ten feet high. Of these stories two have already been built in addition to the concrete pedestal, there remain therefore the seven yet to finish, provided the wall is carried up to its full height. The latter is being made with exterior faces of granite masonry, the hearting or interior being entirely of cement concrete, with large blocks of rubble stone packed into the mass in order to economize the use of cement. The progress of the concrete work is slow and tedious and exacts much careful supervision. It is not, however, without advantage that the process should be a slow one, for this will admit of the thorough setting and hardening of the entire heart before the dam is called into use. There have been instances of work of this description in England pushed forward with undue expedition, where the superposition of large masses of concrete over equally large masses of the same, has had the effect of impeding or retarding the induration of the whole. There will, however, be no need to await the attainment of its final height before utilizing the dam to form a lake. I have said before that this work may be stopped short at any height that money considerations may impose. With a wall only sixty feet high, a volume of water over twice that of the Pokfoolum reservoir can already be impounded, and, if it is decided to raise it higher as the wall continues to be carried up from month to month, and the work dries and hardens, the top water- level of the new lake may also be gradually raised and its contents increased until the ultimate volume desired to be impounded is attained.
In former Departmental reports to the Government I have expressed the opinion that the reservoir would be finished before the tunnel, but latterly, due to the efficiency of the new and heavier drilling machinery, the boring has gone ahead so rapidly, that in the race towards completion between these two works, it is now problematical whether after all, the tunnel will not reach the winning post first. Should this be the case Tytam reservoir water may be used in town earlier in 1887, than I had allowed myself to anticipate.
P
Tunnel. The tunnel in course of construction from Tytam to Wong-nei-Chung for the passage of the waters from the new reservoir to the northern side of the island will be when completed, about 7,300 feet long or roughly speaking, a little under a mile and a third. It is six feet wide and seven feet high from the floor to the crown of the arch, these being the least admissible dimensions consistent with convenience of working. The excavation has been driven so far entirely through a hard, solid and fissured granite formation, that has proved most adverse to progress and there is now no reasonable hope left that the character of the rock will change to anything more favourable.
The mountain is being pierced from both sides in the same straight line and on the same level, and the two headings are now each advancing towards one another at the rate of twenty feet per week and therefore lessening the distance between them by forty feet every week. The Tytam heading has been carried in to a distance of 2,132 feet, and the Wong-nei-Chung heading 1,868 feet, making a total of tunnel finished of 4,000 feet, or over one half of the whole work. There remain therefore about 3,300 feet of tunnel to drive, and at the rate of actual progress which I have mentioned, i.e. forty feet per week,--a progress which there is no reason to doubt will be maintained-it will take eighty-two weeks to
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