108 HOMES WITHOUT HANDS. 



silently and unsuspectedly reduces the plankings and timbers 

 to such a state of fragility, that when struck by the side of a 

 vessel, or even by an ordinary boat, large fragments will be 

 broken off. I have now before me two specimens of " worm- 

 eaten" timber, one of which is so honeycombed by this destruc- 

 tive mollusc, that a rough grasp of the hand would easily crush 

 it. Yet this fragment formed part of a pier on which might have 

 depended a hundred lives, and which was so stealthily sapped 

 by the submarine miners, that its unsound state was only dis- 

 covered by an accident. 



The copper sheathing, with which the bottoms of ships are 

 covered, is placed upon them for the express purpose of baffling 

 the Shipworm, and though so expensive a process, is cheaper 

 than permitting the destructive creature to work its own will on 

 the vessel. It is possible, however, that an equally effectual, 

 and very much cheaper method of protecting ships and sub- 

 merged timber may soon be brought into active operation. 

 M. de Quatrefages has discovered that mercurial salts of any 

 kind are instantaneously fatal to the Shipworm, and that, by their 

 use, not only the existing animals may be killed, but their eggs 

 destroyed also. A vessel that has been attacked by these pests 

 may be rid of them by throwing a few pounds of corrosive sub- 

 limate into the dock where she lies, and it would not be very 

 difficult to keep a special dock for the purpose. 



The most effectual method, however, of checking the ravages 

 of the Shipworm is, by saturating the timber with corrosive 

 sublimate ; a process which is effected by exposing the timber for 

 a long period of time, so as to allow the sap to escape, and then 

 by forcing a solution of the metallic poison into the minute 

 interstices of the wood. This is done in a curiously simple 

 manner, namely, by laying the logs of timber on the ground, 

 introducing a tube into one end, carrying the tube to a height of 

 forty or fifty feet, and then connecting it with a tank filled with 

 the solution. It is, of course, necessary that the timber should 

 be thoroughly seasoned before it is thus treated. M. de Quatre- 

 fages suggests that the prepared wood might be sawn into thin 

 planks, which could then be used in the same manner as the 

 copper sheathing now in use. 



Another species of the same genus. Teredo corniformis, is 

 remarkable for the locality in which it is found. Tliis curious 



