634 PROCEEDINGS OP SECTION J. 



runners properly fixed, so as to ensure the buckets working 

 smoothly. 



Some of the water-bearing drifts are very troublesome and 

 difficult to deal with, and in such cases, if the water has a consider- 

 able rise, with a strong supply, it is often found to be advisable 

 not to sink to the drift, but to stop some few feet above it, and 

 then put down a carefully tubed bore to tap the water. Boring is 

 sometimes resorted to in order to avoid the necessity of puddling 

 back water of bad quality. Framed timber lined with galvanised 

 iron is generally adopted for tanks, although where timber is 

 scarce and stone procurable close to the work, the latter is sub- 

 stituted. Tron-framed, buckled-plate tanks and steel troughing 

 are now being used in preference to timber or masonry on all 

 new works. 



When tanks are constructed in watercourses an embankment is 

 made below the excavation, and in cases where the channel is 

 shallow, and the face of the bed considerable, this dam is carried 

 above the level of the creek banks, and flanking embankments 

 carried on the same level as the dam are continued up each side 

 of the creek until they cut the natural surface of the ground. In 

 other cases, where the face of the bed is inconsiderable, a dam is 

 constructed both above and below the excavation, and these, if 

 raised above the natural level of the creek banks, are joined by 

 lateral embankments ; an inlet pipe is laid under the upper dam, 

 which allows water to gravitate into the excavation and enclosed 

 space until it reaches the level of the water outside ; a valve is then 

 closed, and, if necessary, the outside water is pumped over the 

 embankment into the reservoir. This plan gives a greater depth 

 of water, and shuts off the tank supply from that in the shallow 

 reach above it, and considerably reduces the loss from evapora- 

 tion and soakage. In all works of this character great care 

 must be taken to provide an adenuate bye-wash, and wherever 

 possible the work is so located as to allow of a natural channel 

 being used for the purpose. The number of works completed up 

 to date are as follows : — One hundred and five tanks, twenty- 

 seven wells, and five dams. 



SYDNEY SEWERAGE WORKS. 



The high rate of mortality prevailing in the City of Sydney 

 having attracted serious attention, the Government in the month 

 of April, 1875, appointed a board called "The Sydney City and 

 Suburban Sewage and Health Board," "to inquire into and 

 report as to the best means of disposing of the sewage of the City 

 of Sydney and its suburbs, as well as of pi^otecting the health of 

 the inhabitants thereof." The board consisted of fifteen members, 

 viz. : — Messrs. M. B. Pell, B.A., Professor of Mathematics and 

 Natural Philosophy, University of Sydney (Chairman) ; P. F. 

 Adams, Surveyor-General ; H. G. Alleyne, M.D., Health Officer ; 



