Bucwanan.—On Charring Timber as a Protection from Teredo. ^ 188 
Art. XII. On Charring Timber as a Protection from Teredo. 
Jonn BUCHANAN. 
[Read before the Wellington Philosophical Society, 25th November, 1876.] 
Tux purpose of the following notes is to call attention to some portions of 
charred piles presented to the Colonial Museum by the Hon. G. M. Water- 
house. They were taken from a wharf in Tasmania by Mr. Watson, and 
forwarded by him to Wellington with an accompanying letter, which 
contains matter of much importance at the present time in New Zealand, 
regarding the advantages of charring piles for wharves or other constructive 
marine works. As explained by Mr. Watson, and also as shown by the 
specimens, charred piles thoroughly resist the boring of sea-worms, thereby 
ensuring durability to the works concerned. Specimens are also sent, 
showing the destructive action of the worms on uncharred piles of the same 
species of Eucalyptus. 
The protection of timber by charring from marine worms appears to have 
been a very ancient practice, and sometimes with complete success. As an 
instance of this, charred piles have been found in a sound state in the 
Thames, below London, the driving of which is accredited to the Romans. 
It is strange therefore that this well-known method of protecting timber 
has not been more frequently adopted. 
Charring fence posts to ensure durability is also a common practice, but 
is often brought into disrepute through ignorance of its particular use in 
this case, which is only to prevent beetles boring the post at the surface 
it is called, between wind and water. Charring must 
So much is the necessity for thorough charring 
f the process is essential to success 
of the ground, or, as 
be well done in this case. 
that an intelligent idea of the use o 
in the practise of it. 
In charring timber as a pro 
it ghould always be borne in mind that the 
cal obstruction to the boring apparatus of the worm or beetle; hence the 
necessity of deep charring, and not merely blackening the timber. The 
to the hard mandibles of the worm is exactly similar to 
be found if an attempt were made to bore with an auger 
k; and, indeed, if the bark be left on and charred, the 
tection against marine worms or land beetles 
é , 
charring offers only a mechani- 
opposition offered 
that which would 
into thick fibrous bar 
obstruetion would be more efficient. ; 
It has been proved in Australia that the bark alone, without charring, is 
a sufficient protection against marine worms, but not, as stated by some, in 
virtue of its juices. There is always, however, à tendency in driving piles 
with the bark on that it strips off; but as the process of charring would 
‘make it cling close to the wood, or even become semi-united, the advantage 
of charring with the bark on is obvious. 
