372 TEREDO NAVALIS IN NOVA SCOTIA — MURPHY. 
teredo cannot attach itself, offer only an insufficient protection ; 
these coverings are likely to be injured either by mechanical 
means, such as the action of the water, or by being dissolved by 
the water. Just so soon as a point of surface of the wood is un- 
covered, be it ever so small, the teredo, still microscopic, pene- 
trates into the interior. Covering wood with sheets of copper or 
zine, or with nails, is a too expensive process, and only protects 
the wood so long as they form an unbroken surface. 
2. Impregnation with inorganic, soluble salts, generally con- 
sidered poisonous to fish and animals, does not protect wood 
from the attacks of the teredo. 
3. Although we do not know with any certainty if among 
exotic woods there may not be found these which will resist the 
teredo, we can affirm that hardness is not an obstacle which pre- 
vents the molluse from perforating his galleries; the ravages ob- 
served in wood of guaiacum and mamberlak prove this. 
4. The only means which can be regarded with great certain- 
ty as a true preservative against the injury to which wood is ex- 
posed from the teredo, is the oil of creosote; nevertheless, in 
employing this means care is necessary that the oil be of good 
quality, that the impregnation be thorough, and that such woods 
be used as will absorb oil readily. 
The conclusions arrived at by our Commission are confirmed 
by the experience of a large number of engineers in the Nether- 
lands, and also in England, France and Belgium. M. Crepin, a 
celebrated Belgian engineer, expresses himself thus, in a Report 
on experiments tried at Ostend, under date of February 5, 1864: 
“The result of our experiments now seems decisive, and we 
think we can draw from them this conclusion: that soft woods, 
well prepared with creosote, are protected from the attacks of 
the teredo, and are in a condition to assure a long duration. The 
whole matter, in our opinion, is reduced to a question of thor 
rough impregnation with good creosote oils, and the use of such 
woods as are adapted to the purpose. It has been found that 
resinous woods are impregnated much better than other varieties.” 
Mr. Fourtier, a French engineer at Napoleon-Vendu, in a re- 
port dated March 3, 1864, makes a resumé of experiments con- 
