The Destructive Teredo

The teredo is the most destrnctive marine animal we have. It enters the submerged part of the piling of wharves or railroad trestles and bores into tbe interior. When it penetrates the surface of the wond it is abont the size of a pin, but increases in size, ahvays lengthening, but never leaving any part of tbe hole it boies until its fnll mission is accomplished. In this way it stretches from the original pin hole entrance far into the interior of the wood and swells in size to th9 diameter of a large lead pencil. At the big end are the cutters, two clam shells that rotate from side to side and cut a srnooth, round hole. The worm sometimes attains the length of ten inches. Hundreds of such woiids attack the exposed wood at the same time, and in a short time honeycomb it. However numeroïis they are, they never interfere with one another, and no instance is found where one borer has cut into or crossed the boring of his neighbor, though the partitions left between the boriiigs are sornetimes no thicker tbau. a sheet of paper. Ariothei peculiarity is that as the places of entrance are 110 larger thau pin heads and the worms romain and do their growing inside, the wood may be almost entirely consumed inside, yet the surface appears sound and uuaffected. Suddenly, without the slightest warning, the wooden pile gives way and its fellows follow in short order, and the wbarf which appeared subetantial is wholly rnined. To combat the teredo many expedients have been resorted to. One is to sheathe the piling incopper. Another is to cover the surface of the wood with broad headed tacks - the rust from which spreads soas to discourage the teredo's operations. Still another ruethod is to boi] the wood in creosote under heavy steam pressure, so that the creosote satura tes the fibers of the wood. AH these inethods are efficacious, and the creosote process is used with perfect success in wharf and trestle building all aloiig the gulf coast. lts cost is the chief drawback, a single stick of creosote timber costing soruetimes as mucb as