PROCEEDINGS OF SECTION D. m5 FS 
i$in. In 1840 this gentleman went to look at them again, and 
found them sound. When Mr. Randall took the contract for 
the Circular Quay he did not take the trouble to pull these piles 
out, as they were not in his way, and my informant told me 
where to go and find them, so this specimen must be seventy- 
three years old. There is the Ironbark quite sound” (g). No 
doubt these piles were effectually protected by the foul and 
muddy water. 
A proposal, which cannot be considered practical, is to destroy 
the shipworms by pouring such a poison as corrosive sublimate 
into the water in which infected piles stand, especially directing 
it against larva and spermatozoa as they issue from the parents. 
The volume of sea-water to be treated is an insuperable obstacle 
to this plan. 
Any method which protects timber from the ravages of ship- 
worms will incidentally save it from boring Crustaceans. 
Artificial protection has proceeded along two directions—to 
render the interior proof against perforation, and to sheath the 
external surface with a substance impenetrable by the shipworm. 
In the former direction, various experiments have been con- 
ducted in Europe and America with creosote. Ten to sixteen 
pounds of heavy creosote to the cubic foot was forced into the 
timber before the piles were driven in. This process has yielded 
very uncertain results, and cannot be relied on to protect the 
wood. Only the lighter and more absorbent kinds of timber ad- 
mit of saturation. The dense woods usually employed by Aus- 
tralasian constructors do not lend themselves to this treatment. 
The cooking which the wood undergoes in the process renders it 
brittle, and unfits it for pile driving. 
In defending timber by some worm-proof coat it is necessary 
to extend the armour over the area of contagion, which is from 
half tide level down to the ground. How deep the Cobra goes 
is uncertain. A deep record is 1400 fathoms, east of Cape York, 
Queensland (h), but this may represent a log infected and water- 
logged and sunk, not infected where it was found. 
An even deeper record is that of Xylophaga abyssorum, which 
burrowed in the hempen covering of the first Atlantic cable at a 
depth of over 1500 fathoms (2). 
The most primitive method of obtaining an impenetrable coat 
for piles and vessels was to thoroughly char the whole external 
surface. Dr. Wright describes how “The Hindoo fishermen 
suspend the boat infested across two upright poles and light a 
fire beneath it, which in a short time destroys all the mollusks, 
and by slightly charring the wood hinders for some time a second 
attack” (7). In the seventeenth century the Portuguese mariners 
(7) Booth. Report from the Select Committee on Wharf Accommodation in Sydney 
Harbour. 1874, p. 20. 
(h) Smith. Challenger Report. Zoology, xiii, 1885, p. 27. 
(i) Dall. Bull. Mus. Comp., Zool., xii, p. 318. 
(j) Wright. Op. cit., xxlv., p. 452. 
