WHARF CONSTRUCTION, SYDNEY HARBOUR. XLV. 
are from unsheathed turpentine piles. The value of the turpentine 
is here very apparent. 
6. A longitudinal section cut from an unsheathed turpentine 
pile driven in Dalton’s wharf in 1877, and drawn after 28 years’ 
service. This sample illustrates what I have contended in the 
body of the paper, viz., that the most destructive borer to turpen- 
tine is not ship-worm but Limnoria and Sphaeroma. The large 
gap on the right hand side is the work of the Limnoria; the 
irregular erosion on the left side the action of the Sphaeroma. 
The cobra holes are insignificant. I might remark that Mr. 
Hedley, Conchologist at the Australian Museum, asserts in his 
article previously referred to in this paper, that the ship-worm in 
our waters is not quite the same as that which works so much 
destruction in European waters. He also expresses the opinion 
that the Limnoria terebans is probably not indigenous to these 
waters, but was originally imported by wooden ships trading here 
in the early days. 
7. A longitudinal section of a blackbutt pile upwards of 50 
years old, lately drawn from the head of Darling Harbour. This 
sample indicates that when the pile was driven the water, nearly 
as far up as the foot of Liverpool Street, was clean enough for the 
marine borers to be able to attack the timber. But after some 
years the water evidently became so greatly charged with sewage 
matter that the work of the borers was arrested. The deposit of 
dirt on the skin of this pile is very apparent when compared with 
sample No. 6, which was driven in clean water. 
8. A portion of a yellow metal bolt drawn from the swing span 
of the old Pyrmont Bridge after 9 years’ immersion in salt water. 
All the bolts drawn from the same structure and having been put 
in at the same time, were so brittle that they could not be got out 
without being broken in several pieces. This has been a common 
experience with yellow metal bolts in recent years. 
9. Samples of yellow metal sheathing, showing conditions after 
various lengths of service. 
