and mahogany are examples of woods which discourage their advances. It has been stated that Robert Stevenson (not the son of the "Father of Railways"), of Edinburgh, at Bell Rock Lighthouse (of which he was engineer), between 1814 and 1843, found that greenheart wood, beef wood, and bullet tree were not perforated by the Teredo navalis, and teak but slightly so. Later experiments show that the "jarrah" of the East, also, is not attacked. Lignum vitæ is said to be exempt. The cost of these woods prevents their general use.

In 1810, Stevenson first noticed the teredo in piles, and specimens of the creatures in wood were sent to Dr. Leach, of the British Museum, in 1811, who examined them, and noticed their peculiarities. Stevenson, settled on Bell Rock during many years (like a new Robinson Crusoe), was enabled to watch the injuries done to the piles by the teredo. With piles which had been subjected to Kyan's process before immersion, the wood was attacked at the end of the twenty-eighth month, and was entirely destroyed in the seventh month of the fifth year. With Payne's, it lasted a year longer.

We can give the names of those who have given much time and attention to this subject. At the bottom of this page a list of works of reference* will be found useful. Messrs. Stevenson (engineer of Bell Rock Lighthouse), Harting (Member of the Academy of Sciences of the

* See 'Proceedings of the Royal Society of Edinburgh,' v. 7, page 433; 'Tredgold's Carpentry,' by J. T. Hurst, 1871; 'Histoire de l'Acad.,' 1765, page 15; 'Ann. des Ponts et Chaussées,' v. 15, page 307; 'Mem. sur la Conservation des Bois à la Mer,' 1868, by Forestier; 'Bois de Marine,' by Quatrefages, 1848.

Pays-Bas), de Quatrafages, Deshayes, Caillaut, Hancock, Dagneau, de Gemini, Kater, Crepin (Engineer-in-Chief, of Belgium), and A. Forestier (Engineer-in-Chief of the Bridges, &c., of France).

The termite, or white ant, is the most destructive insect to timber on land, whilst the teredo reigns supreme of sea worms in the sea. The former we shall treat of in our next chapter, the latter we propose considering at some length in this.

The marine worm, of which there are accounts in all parts of the world, has been known, by its effects, for hundreds of years; indeed, Ovid spoke of it nineteen hundred years ago, and it is even mentioned by Homer. Fossil terredines of great antiquity have been found near Southend; also pieces of petrified wood from the greensand, near Lyme and Sidmouth, bored by ancient species of teredo; also from Bath, and from Doulting, near Shepton Mallet, specimens of oolite, with petrified corallines in it, pierced by boring shells.

It is said that this worm is a native of India, and that it was introduced to Holland some 200 years ago, from whence it has spread through the ports of northern Europe.

The Teredo navalis* is very destructive to harbour works and piling. The Southampton water is particularly infested with it; in fact, the teredo is found in every port to which coals are carried south of the Tees; in the Thames, as high up as Gravesend; and northward as far

* There are eight kinds of teredines, of which three are to be found in European waters, viz. the Teredo fatalis, Teredo navalis, Teredo bipennata.

as Whitby. It is also found at Ryde, Brighton, and Dover. Traces of the ravages of the Teredo navalis, and of the Limnoria terebrans, have at various periods been found from the north of Scotland and Ireland, on almost every coast, to the Cape of Good Hope and Van Dieman's Land, in the eastern hemisphere; and, in the western. hemisphere, from the river St. Lawrence to Staten Island, near Terra del Fuego, almost in the Polar Sea; so that although this maritime scourge is rifest in warm climates, yet cold latitudes are not exempt from it.

At the Crystal Palace, Sydenham, may be seen the destructive Teredo navalis in a bottle, and there may also be seen mahogany perforated by it, and fir piles from Lowestoft Harbour, which were rendered useless by the ravages of the worm and the limnoria three years after they were driven, showing the necessity of defending timber intended for marine construction. A specimen of American oak from the dock gates of Lowestoft Harbour, which had been four years under water, and a part of a fir-pile from the dockyard creek at Sevastopol, also show the destructive powers of the teredo. At the South Kensington and British Museums, London, specimens of this worm may also be seen, as well as pieces of timber perforated by it.

The bottoms of ships, and timbers exposed to the action of the sea, are often destroyed by the teredo.

The gunboats constructed during the Crimean war suffered far more from dry rot and the teredo than the shot and shell of the Russians. One cannot even guess at the mischief perpetrated every year all along our

shores, in docks and harbours, by the boring animals that penetrate all woods not specially protected. We cannot count the number of the ships that have foundered at sea, owing to those few inches of timber, on which all depended, being pierced or destroyed by the worm or fungus.

In the short space of twelve years these destructive worms were known to make such havoc in the fir piles of a bridge at Teignmouth, that the whole bridge fell suddenly, and had to be totally reconstructed.

The wooden piers of Bridlington were nearly wholly destroyed by worms; and the pile fenders on the stone piers at Scarborough were generally cut through in a few years.

At Dunkirk, wooden jetties are so speedily eaten away that they require renewal every twelve or fifteen years. At Havre, a stockade was entirely destroyed in six months. At Lorient, wood only lasts about three years in the seawater; and at Aix, the hull of a stranded vessel was found to have lost half its weight in six months, from the ravages of these animals.

The reason why Balaclava, in Russia, is not a place of considerable mercantile importance is owing in a great measure to the destructive ravages of the worms with which its waters are infested, and by which the hulls of ships remaining there for any length of time become perforated.

The piles of the jetties in Colombo Harbour, Ceylon, which are mostly of satinwood, and about 14 inches in diameter, are so pierced by these worms in the course of twelve months as to require renewal. ·