XXXVI. H. D WALSH. 
Wharf and others, and I confidently look forward to a life 
of 30 years for these wharves. Without taking into con- 
sideration the piles in the numerous small jetties and private 
structures, or those used in sheet piling along the fore- 
shores (numbering probably 3,000), there are standing in 
Sydney Harbour some 7,000 unsheathed turpentine wharf 
piles ; of these I have driven over 2,600 during the past 5 
years. The majority of the remaining 4,400 have been 
standing from 20 to 30 years. In turpentine timber it is 
evident we possess a highly valuable element of wharf 
construction, which should be made the most of as long as 
it is procurable at a reasonable price. 
I may here mention that with one exception, all the 
wharves in Circular Quay and Woolloomooloo are con- 
structed of ironbark piles sheathed with yellow metal. 
These were constructed some years ago at a time when 
yellow metal could be relied upon as a safe protection for 
the piles, but as will be shown later on in this paper, 
suflicient reliance cannot now be placed in the metal pro- 
curable in this State, to warrant its use in this way. I 
regard ironbark when sheathed as the most durable of all 
our timbers for piles. Some time ago we took up the old 
Pyrmont Bridge, the piles of which were of ironbark 
sheathed with Muntz metal, and had been standing in salt 
water for 48 years, practically the whole of the piles which 
measure about 50 feet in length were sound, and I have 
driven them again in the construction of the new Pyrmont 
Bridge Wharf. The metal sheathing was upon the whole 
in bad condition, having disappeared in patches. But, 
owing probably to the amount of sewage in the water 
marine borers had not injured the timber to any appreciable 
extent. What remained of the sheathing was fairly good 
and testified to the good quality of the metal, as may be 
seen by the sample submitted. The heads of the piles for 
