372 TEREDO NAYALIS IN XOYA 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 

 zinc, 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 mollusc 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 Beport 

 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 tho- 

 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 resume of experiments con- 



