76" The Teredo Navalis on Colonial Timber. 
the soundest parts above and below the worm-eaten portions, 
and again at two points between these, and the results were 
as follows :— 
ft. in. ft. in. ft. in. ft. in. 
Girth above 3 44 Girth at worm- (3 1 \ 
3 22 m 0 
Sane A { — below 3 og mean 3 eaten parts Me 0 car ee 
Girth above 3 23 Girth at worm- ¢ 2 103 
ae Bt — below 2 11 } mean 3 8 eaten parts 2 oj pean ries 
By this it would appear that the first pile had been reduced 
in diameter about half an inch, and the second pile about 
one inch. As, however, the measurements were taken round 
the outside of the perforations made by the worm, this would 
not of course give an accurate estimate of the amount of 
injurydone. ‘The piles were therefore carefully scraped at the 
points where the measurements were made, until all trace of 
the action of the worm was nearly obliterated, or till the sound 
timber was seen; the measurements being then taken, the 
results were as below :— 
ft. in. ft. in. ft. 
Girth at worm- {3 0 Girth of sound timber ...... 3 2h 
mean 2 10 j Fe ie 
ae. f eaten parts 2 a 3 Mean of worm-eaten part ...... 2 104 
Miiffenence went 0 4 
PILE B Girth at worm- (2 8} mean2 7 Girth of sound timber ........ 3 OF 
eaten parts 27 Mean of worm-eaten part...... 2 7 
SD TTETENCE Ns leleeieteleleleteie 0 5 
The mean of these differences would be 43 inches in girth, or 
13 inches in diameter. 
The absolute amount of the action of the worm in the 
harbour of Hobart Town from these observations would 
appear to be equivalent to a reduction of 13 inches in the 
diameter of a round pile in eight years, or at the rate of 
about one-fifth of an inch per annum. 
I do not give this as a fact sufficiently established to form 
the basis of an estimate, but as an approximation ; and I 
should wish to suggest to others the advisability of commu- 
