362 ANNUAL OF SCIENTIFIC DISCO VERY. 



up to the light after the death of the animal, the meandering of the worm can 

 be traced very close to the outside, and as close to the inside surface ; but 

 never passing through into the water, or to open space inside of the surface. 

 As they progress through the wood, they take care to keep in separate cells ; 

 and how strange it is, when their mouth-pieces come to an inconceivable 

 thinness of the outside surface, or very near one of their species, they " try 

 back" turn from the opening they would cause by interfering with their 

 neighbor's habitation. 



Many vessels proceed to sea having parts of their bottoms destroyed, which 

 is unknown to the captain, owners, or underwriters. One nail-hole in a sheet 

 of copper neglected, having no nail driven in to stop the vacancy, might be 

 the cause of the loss of a ship ; for wherever the water has access to the wood, 

 certainly there the worm will be found. A ship with a copper bottom may 

 be in Norfolk harbor, and her bottom supposed to be perfect ; at the same 

 time one or two sheets of copper may be off, and the worms may have com- 

 pletely destroyed the inside of the plank that is betwixt the inner and outer 

 surface. This perforated part of the bottom may strike against a hard object 

 at sea, the plank be broken in, and the ship lost. I do not doubt the above 

 has frequently been the case. "Where a ship's bottom is not protected with 

 copper, frequent search should be made for these animals, by which many 

 lives might be prolonged and valuable property saved. 



It has been observed by a writer, that these animals do a great benefit 

 to commerce by destroying the floating wrecks at sea, and sunken logs in 

 harbors. 



In specimens of wood which are left in the river for more than one season, 

 there will be found, after the winter has passed away, the animal alive in 

 many of the cells. There will be seen also many cells without the animal : 

 after its death the shell gets broken, and the animal (a mere paste) is washed 

 away by the waters. 



I believe I have said enough of these enemies to the commercial world, to 

 all foundations requiring piling, and to the wood material generally, wher- 

 ever kept in the salt water in a temperate climate. 



In regard to the preventives against the ravages of these destructive 

 creatures, I will offer a few remarks. 



Tredgold says that they never touch bitter wood. I tried all kinds of wood 

 used in building ; they bore all. He also says, that charring the surface is 

 not found to be of any use. He is certainly mistaken : no worm is found in 

 charcoal ; it is too pure. The charcoal must rub off before the worm can do 

 damage ; a pile may remain submerged for a century, if the charcoal part be 

 perfect. Should the charred part be worn*bff by the ebbing and flowing of 

 the tide, and the wood be subject to the action of the water, the sb ell-fish is 

 sure to appear. One great neglect in charring is, that the heat required to 

 burn the wood to charcoal on its outside surface will cause a disruption, a 

 fissure, that the fire does not reach ; this crack remains uncharred, the water 

 reaches the naked wood, and the terrible animal appears. Fill these fissures 

 or cracks with hot coal tar, and the piles will be safe as long as the charring 

 is perfect, and the coal tar does not pass off: or you might fill the fissures 



