352 REPORT OF THE FOREST, FISH AND GAME COMMISSIONER. 



Besides charring, coating and impregnation, there are a few other 

 methods of protection which have had some success, and which deserve 

 mention, although it is now generally recognized that no method compares 

 in effectiveness with impregnation, and especially impregnation with dead 

 oil of coal tar, or creosote. 



Removal of submerged timber during the breeding season of the borers 

 has been tried, but it is often impracticable, and always so when the 

 breeding season is long, as it is in the South. 



A change of water will sometimes save timber from the attacks of 

 marine borers. Wooden vessels have sometimes been hauled into fresh 

 or muddy water and thus made immune. The suggestion has been made 

 that expensive wood-work might be surrounded by fresh water, which is 

 never infested by the teredo, limnoria or chelura. 



It is claimed that if the bark is left upon piles when submerged they 

 will be safe against attacks by the teredo, which seems to be reluctant 

 to cross seams. But this method is hardly of any use against the limnoria; 

 and the bark soon wears away, when the pile is as vulnerable as manu- 

 factured lumber. 



Metallic sheathings, such as copper and zinc, have been used with 

 considerable success. The chief objection to such sheathing is the large 

 cost, because it cannot be denied that they are effective, especially sheath- 

 ings of copper. 



Sheathings of many other materials have been tried. Such attempts 

 have included : 



A mixture of paint with some fabric such as burlap or wire netting. 



Paraffine, tar, asphalt, etc. 



i 

 Portland cement. 



A jacket of ordinary cylindrical sewer-pipes of earthenware, with joints 



sealed. 



"Teredo nails," sometimes called "worm nails," have been in use in 

 Holland for many years, arid are said to have been employed by the ancient 

 Romans. They have short spikes, with large, flat heads. These nails are 

 driven into the piles, or piece of timber, very close together, and are reported 

 to be very effective in repelling the teredo. But the nails rust and wear 

 out in time, and have other disadvantages. 



