THE TEREDO AND ITS DEPREDATIONS. 557 



a point of surface of the wood is uncovered, be it ever so small, the 

 teredo, still microscopic, penetrates 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 consid- 

 ered poisonous to fish and animals, does not protect wood from the 

 attacks of the teredo. This want of efficacy must be attributed in part 

 to the fact that the salts absorbed by the wood are extracted by the 

 dissolving action of sea-water, and in part, also, because those salts do 

 not appear to have a poisonous effect upon the teredo. 



3. Although we do not know with any certainty if, among exotic 

 woods, there may not be found those which will resist the teredo, we 

 can affirm that hardness is not an obstacle which prevents that mollusk 

 from perforating his galleries ; the ravages observed in the wood of 

 guaiacum and mamberklak prove this. 



4. The only means which can be regarded with great certainty as a 

 true preservative against the injury to which wood is exposed 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. 1 



The conclusions arrived at by our commission are confirmed by the 

 experience of a large number of engineers in the Netherlands, 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 

 thorough impregnation with good creosote-oils, and the use of such woods as 

 are adapted to the purpose. It has been found that resinous 2 woods are im- 

 pregnated much better than other varieties." 



M. Forestier, a French engineer at Napoleon-Vendee, in a report 

 dated March 3, 1864, makes a resume of experiments conducted by 

 himself in the port of Sables-d'Olonne, in the following words : 



" These results fully confirm those established at Ostend, and it seems to us 

 difficult to refuse to admit that the experiments at Ostend and Sables-d'Olonne 

 are decisive, and prove in an incontestable manner that the teredo will not 

 attack wood properly creosoted." 



Under date of Haarlem, April 20, 1878, Prof. Von Baumhauer writes 

 to Edward R. Andrews, of Boston : 



" I have deferred answering your favor of the 22d of February until I had 



1 The efficacy of creosote-oil in protecting wood from decay and marine worms is 

 largely due to the fact that it is insoluble in water. E. R. A. 



s The yellow pine of the Southern States absorbs oil very readily. E. R. A. 



