1886. | The. Teredo, or Shipworm. 135 
eighteen months, and have heard of even a more rapid destruc- 
tion of wharf piles in the harbor of that city. In one instance 
reported to me the destruction was accomplished in about six 
months. In the case which came under my notice, as above, the 
wood of the pile had not lost its original fresh or bright appear- 
ance when it had to be removed from the wharf and a new one put 
in its place. My friend, Mr. Dall, informs me of a case of the de- 
struction of the supports of a small pier made of piles (probably 
pine) six to eight inches in diameter in about six weeks. The 
structure was at one of the small capes near the entrance to 
Chesapeake bay. 
As the shipworms are gregarious, and furthermore as they grow 
and multiply with astonishing rapidity, their destructive work is, 
as shown above, often accomplished in a very short time. 
The extent of their operations and the money loss entailed 
thereby, both upon private parties and business corporations en- 
gaged in commercial marine enterprises and on the naval equip- 
ment and appurtenances of the great maritime nations, are enor- 
mous. 
This has led to a great number of experiments by govern- 
ments and inventors for the protection of wood work used in 
Marine structures. 
Jeffreys remarks that “in all probability the constitution of a 
shipworm is poison-proof,” Most of the remedies proposed in the 
last century were of this nature, and they signally failed. 
The saturation or impregnation of the wood with creosote or 
some other carbolic preparation by hydrostatic pressure, the 
kyanizing of piles, and sheathing with copper, the filling of the 
exposed surface with large-headed nails have all been tried. The 
two last, copper sheathing and scupper nailing, Jeffreys says, — 
“have been successfully used, but the former is expensive and 
the crust of iron (unless they are closely driven in so as to com- 
pletely cover the piles) is superficial and liable to scale off. I 
have known the Teredo to bore through a pile which was sup- 
posed to be protected by large broad-headed nails in the usual 
way. At Christiania, in April, 1863, I found that Teredo navalis 
was very destructive to the woodwork in the harbor, and to boats 
lying at anchor in the fiord. The chief engineer told me that all = — 
the piles had been creosoted (ten pounds to the square foot) be- 
re they were driven in, but not to much purpose!” 
