CAUSES OF DECAY AND DESTRUCTION OF TIMBER 267 



the surface and makes a hole from to f inch diameter 

 and about 2 inches deep. 



An excellent shout and interesting paper dealing with 

 these timber borers, by Mr. Charles H. Snow, M.A.Soc.C.E., 

 is published in the Proceedings of the American Society of 

 Civil Engineers, Vol. XL., 1898. 



So far as the author knows, there is no wood which is 

 not liable to attack by the sea worm with the possible 

 exception of billian from North Borneo, and that has not 

 been much used, but appears immune, and some of the 

 palms or similar timbers which the teredo will not generally 

 attack, as the animal prefers a compact wood for its abode. 

 In the paper previously referred to Mr. Walsh mentions 

 turpentine as the only Australian timber which the teredo 

 dislikes, and he found this timber quite sound after an 

 immersion of thirty to forty years, although occasionally the 

 sapwooi showed signs of attack by limnoria and sphseroma. 



Engineers for a long while pinned their faith on green- 

 heart, as it was considered that the sea worm would only 

 attack the sapwood of that timber, and greenheart certainly 

 resists the attack of the worm for a longer period than any 

 other timber in general use, but, as has been pointed out 

 elsewhere, it is now known that even greenheart only lasts 

 for a limited time in places where the teredo or limnoria 

 is active. 



These borers will not attack certain timbers if others 

 more to their liking exist in the neighbourhood, hence the 

 reason of the statements so frequently made to the effect 

 that many timbers are proof against the marine worm. 

 Piles standing by themselves appear to be more open to 

 attack than when placed close to others. 



White Ants. Boring insects of other kinds attack timber 

 all over the world. The most destructive is the termite 



