SOME RECENT ENGINEERING EXPERIENCES. 971 
Australia has, from a social and commercial point of view, been a 
success. Our work has been more economically done, and J chal- 
lenge criticism as to its quality. 
One of the most important engineering questions which my 
department has had to deal with in recent years has been the 
attempt to carry out the very wise and liberal policy of the 
Government, and answer the demand for “cheap water” for 
domestic purposes and stock over large areas of dry country. In 
one district alone nearly 1,000,000 acres have been closely reticu- 
lated with cast-iron pipes varying from 2,/inches to 12 inches 
diameter. Into a history of our progress in water conservation 
it isnot my purpose to enter, but to relate some of our experiences 
in the use of the cheaper descriptions of reticulation pipes. The 
instance which I choose as an illustration is a steel main 70 
miles in length, 16 inches and 17 inches diameter, formed of 
riveted plates, and varying in thickness from 1-16 in. to 5-16 in., 
working under pressures varying from 0 to 300 lb. per square 
inch. Long lengths of this main are of plates 12 and 14 LS.G., 
and the use of such thin plates is, I believe, unique in permanent 
works. They were manufactured under contract, and have been 
in use for over three years, and the results are noteworthy. 
The coating was of the usual asphalt composition, ‘Tn long 
lengths the pipes are as good as when laid, but in some places 
they have failed, having been pitted from the outside and rusted 
into holes ; in a few instances, even the heads of the rivets having 
disappeared. This unsatisfactory result has occurred where the 
main was laid in damp clay formation. The clay has been found 
to have an affinity for the asphalt coating, with which it seems 
to amalgamate, and then by contracting draw it away from the 
plates, leaving them quite clean and exposed to the destructive 
action of whatever salts may be in the soil. When these cheap 
pipes were laid it was recognised that the coating was all 
important, and to find it thus removed from the steel is disap- 
pointing. The pipes laid in limestone or gravelly country are 
intact, the tenacious clay referred to being the cause of the local 
failure. There is naturally a popular re-action against the steel 
pipe as a whole, but to an engineer this is unreasonable. A cement 
coating has been tried with success on some of these damaged 
pipes, but is costly in application, and there is no adhesiveness 
between it and the steel. The cure seems to be the laying of the 
main coated with asphalt, on a gravel bed, and surrounded with 
limestone rubble or some other similar material so as to prevent 
the clay when filled into the trenches from touching the coating. 
Whether this will lengthen the life of the very, thin ] pipes so as to 
justify their continued use in new work remains to be seen, and 
the experiment will doubtless be watched with interest. In the 
meantime, I am laying no new steel pipe less than 3-16 inch in 
