WOODS WHICH RESIST SEA WORMS.Australia, Western.—Jarrah, beef-wood, tuart.Bahama.—Stopper-wood.Brazil.—Sicupira, greenheart.British Guiana.—Cabacalli, greenheart, kakarilly, silverballi (yellow).Ceylon.—Halmalille, palmyra, theet-kha, neem.Demerara.—Bullet, greenheart (purple heart-wood), sabicu.India.—Malabar teak, sissoo, morung sál, dabu, than-kya, ilupé, anan, angeli, may-tobek. (Teak resists theteredo, but is not proof against barnacles.)Jamaica.—Greenheart.North America.—Locust.Sierra Leone.—African oak, or tortosa.South America.—Santa Maria wood.Philippine Islands.—Malacintud, barnabá, palma-brava.Tasmania.—Blue gum.West Indies.—Lignum vitæ.
Australia, Western.—Jarrah, beef-wood, tuart.
Bahama.—Stopper-wood.
Brazil.—Sicupira, greenheart.
British Guiana.—Cabacalli, greenheart, kakarilly, silverballi (yellow).
Ceylon.—Halmalille, palmyra, theet-kha, neem.
Demerara.—Bullet, greenheart (purple heart-wood), sabicu.
India.—Malabar teak, sissoo, morung sál, dabu, than-kya, ilupé, anan, angeli, may-tobek. (Teak resists theteredo, but is not proof against barnacles.)
Jamaica.—Greenheart.
North America.—Locust.
Sierra Leone.—African oak, or tortosa.
South America.—Santa Maria wood.
Philippine Islands.—Malacintud, barnabá, palma-brava.
Tasmania.—Blue gum.
West Indies.—Lignum vitæ.
Second. The chemical, viz. Kyan’s process of corrosive sublimate; Payne’s process of sulphate of iron andmuriate of lime; pitching and tarring; Burnett’s process of chloride of zinc; and arsenic, or other mercurial preparations, have all failed, with the exception of Bethell’s process of oil of tar. The failure must proceed from one of two causes; either that the sea-water decomposes the poisonous ingredients contained in the wood, or that these poisonous compounds have no injurious effect on the worms; it appears, however, that both these causes have been in operation, principally the latter.
Without a series of the most minute experiments, it is impossible to form any general notion of the action of sea-water on timber. Common salt, chlorides of calcium and magnesium, sulphate of soda, iodides and bromides of the same metals, are known to exist in sea-water, and in great abundance in the torrid zone. What effect these different ingredients may have upon saturated timber it is difficult to say, but it is extremely probable that they do have an effect.
With regard to the different poisonous compounds having no injurious effect on the worms, it should be remembered that all cold-blooded animals are much more tenacious of life than those of a higher temperament, and in descending the scale of animal creation, the tenacity of life increases, and this principle is more developed. A frog, which though cold-blooded, is an animal of a much higher order than theteredo, will not only live in hydrogen gas, but also in a strong solution of hydrocyanic acid, while at the same time a single drop placed on the nose of a rat, or in the eye of a rabbit, would produce instant death. A somewhat similar occurrence is noticed in the‘British and Foreign Medical Review,’ for July, 1841, showing the slow effects of prussic acid on the common snake and turtle.
It may therefore be inferred, that as it requires a large quantity of the most virulently poisoned matter to destroy animals of a much higher order than theteredo, it would take a still greater quantity to affect those animals as they exist in their own element.
The preserving property of soluble salts, such as corrosive sublimate, sulphate of copper, &c., was considered to be founded upon their power of coagulating the albumen, and the sap of wood, thereby rendering that sap less liable to decay; but that very quality of combining with the albumen, destroyed the activity of the poison of the salts. A given quantity of corrosive sublimate of mercury, which if administered to a dog would kill it, would, when mixed with the white of an egg, become coagulated, and if swallowed in that state would be perfectly harmless; so a piece of wood, saturated by those salts, could be eaten by a worm without injury.
A French naturalist, M. de Quatrefages,[21]in 1848, suggested that a weak solution of mercury (corrosive sublimate) thrown into the water will destroy the milt of theteredo, and consequently prevent fecundation of the eggs, thus exhausting the molluscs in the bud. He proposed that ships should be cleared of this terrible pest by being taken into a closed dock, into which a few handfuls of corrosive sublimate should be thrown andwell mixed with the water. He considered that about 1 lb. of sublimate would be sufficient for 20,000 cubic metres (metre = 39·37 English inches) of water; but on account of the cost it would be advisable to use salts of lead or copper. This proposition of de Quatrefages reminds us of Chapman’s suggestion, in 1812, to get rid of dry rot in ships, viz. by sweeping out the hold, laying from two to four tons of copperas in her bottom, and as much fresh water let in upon it as would make a saturated solution to soak into the wood.
M. de Quatrefages placed the four salts he used in his experiments in the following order, according to merit: 1st, corrosive sublimate; 2nd, acetate of lead; 3rd, sulphate of copper; and 4th, nitrate of copper.
In America, white oxide of zinc is used as a marine paint for ships and piles. In the United States Navy Yard at Gosport it is spoken well of, and very frequently employed. It is said to be much superior to white-lead, red-lead, verdigris, or coal-tar, and that timber covered with two coats of white zinc is neither attacked by the worm, nor do barnacles attach to it when immersed in salt water.
We can only find one instance of timber impregnated with water-glass having been tested against this subtle foe. Water-glass is certainly worth a further trial.
The instance we refer to occurred about forty years ago. In 1832, Dr. Lewis Feuchtwanger, of New York, was permitted by the Ordnance Department, under the direction of Commodore Perry, to perform experiments with water-glass on piles in the Brooklyn Navy Yard, andin various docks. The piles in the docks were destroyed by theteredoso fast that theyhad to be replaced every three years. The experiments proved highly satisfactory: the piles which had been so treated lasting many years, without any indication of being attacked by sea-worms.
The reader is referred to some works on water-glass mentioned below,[22]which are worthy of attentive perusal.
Third. The mechanical processes. They are few in number, and rather expensive.
At Saint Sebastian, in Spain, the piles of the wooden bridge standing in the sea have been guarded against the attacks of sea-worms in the following manner: Each pile is surrounded by a wooden box, and the space between filled up with cement. After six years it was proved that the piles were in a perfect condition, whilst the outer boxes were completely riddled by the worms. A similar method to this was adopted, some years since, to many of the piles in the Herne Bay Pier, which were affected by sea-worms. Several attempts had been made to protect the timber, by saturating it under various processes, with, however, only doubtful success. At last, a wooden casing was formed round each pile, leaving a space of about an inch all round, which was rammed full of lime or cement concrete. That process appeared to be perfectly successful, as the pier-master, who first adopted the method, stated that some of the piles had been so treated for three or four years, and although the worms had commencedtheir ravages, they appeared to have been checked, and not to have been able to exist when so enclosed.
In 1835, Brunel suggested an easy way of defending piles, which was to give them in the first instance a coat of tar; then powder them with brick-dust, which would render the wood sufficiently hard to receive a coat or two of cement. This is similar to the Dutch method.
Some foreigners use sheet lead nailed on to piles, and wrapped close round with well-tarred rope.
Copper sheathing has often been used for the protection of piling in piers and harbours. The destruction of copper by the action of sea-water is a matter which has long occupied the attention of scientific men, and it appears to be well ascertained that the decay does not result from the bad quality of the copper, for, according to Mr. Wilkinson, no difference could be discovered between the composition of copper that had endured well, and that which had been rapidly destroyed. Copper sheathing was used at Southend, but without success, for although nearly all the piles were covered with it for about 9 feet or 10 feet, thelimnorianot only penetrated between the copper and the timber, but the copper had decayed to such an extent as in some cases to be no thicker than the thinnest paper; it was soft, and peeled off the wood very easily, and in two or three years would probably have been entirely destroyed.
Covering the surface of the timber with broad-headed scupper nails, arranged in regular rows with their heads at no great distance from each other, is a method which has been satisfactorily employed in various parts of the world,in Swedish and Danish vessels, even up to the present time, and, indeed, it was also practised by the Romans. The scupper-nailed piles at Southend, after twelve years’ exposure to the sea, were perfectly sound, and although the nails were not driven close together in the first instance, yet the corrosive action was so great as to form a solid impenetrable metallic substance, upon which the worms refused to settle. Scupper nails have been proved at Yarmouth, as well as at other places, to have protected timber for forty years, but the process is expensive, as it costs one shilling per square foot. They should be about half an inch square at the head.
Captain Sir Samuel Brown, R.N., states that from numerous experiments and observations, he is satisfied that at present there is really no specific remedy against the attacks of sea-worms upon timber, except iron nails. He proposes to encase the piles with broad-headed iron nails resembling scupper nails, but considerably larger, and he says that in the course of a few months corrosion takes place, and spreads into the interstices. The rust hardens upon the pile, and becomes a solid mass which the worm will not touch. Experiments tried at the Trinity Pier, Newhaven, and Brighton Pier, have established the effectiveness of his method.
At the Cape of Good Hope, and many other places, wood piles are cased in iron, and occasionally iron piles are used instead of wood, at great cost. Further experience is desirable as to the durability of cast iron[23]in saltwater, especially as to its peculiar property of conversion, after a few years’ immersion in the sea, into a carburet of iron, closely resembling plumbago, so that it may be easily cut with a knife. This, of course, diminishes its powers of resistance acting upon the framing it is intended to strengthen. In the course of the construction of the Britannia Bridge, about one hundred thin plates were delivered, which were not used on account of some error in their dimensions. They were left on the platform alongside the straits, exposed to the wash and spray of the sea; and after about two years were literally so completely decomposed as to be swept away with a broom into the water, not a particle of iron remaining.
We have already stated that the chemical processes have failed with the exception of Bethell’s process of oil of tar, generally known as the creosoting process. This method,when properly carried out, thoroughly protects wood from the ravages of theteredoand other marine worms. The breakwaters and piers at Leith, Holyhead, Portland, Lowestoft, Great Grimsby, Plymouth, Wisbeach, Southampton, &c., have been built with creosoted timber, and in no case have theTeredo navalis,Limnoria terebrans, or any other marine worms or insects been found to attack these works, as certified to by the engineers in whose charge the several works are placed. In the cases of Lowestoft and Southampton we are enabled to give the detailed reports.
A most searching examination, lasting many days, was made in 1849, upon every pile in Lowestoft Harbour, by direction of Mr. Bidder; and the report of Mr. Makinson,the Superintendent of Lowestoft Harbour Works, contains the subjoined statement:
“The following is the result, after a close and minute investigation of all the piles in the North and South Piers.
“North Pier.—The whole of the creosoted piles in the North Pier, both seaward and inside the harbour, nine hundred in number, are sound, and quite free fromteredoandlimnoria.
“South Pier.—The whole of the creosoted piles in the South Pier, both seaward and inside the harbour, seven hundred in number, are sound, and quite free fromteredoandlimnoria.
“There is no instance whatever of an uncreosoted pile being sound. They are all attacked, both by thelimnoriaand theteredo, to a very great extent, and the piles in some instances are eaten through. All the creosoted piles are quite sound, being neither touched by theteredoor thelimnoria, though covered with vegetation, which generally attracts theteredo.”
There was only one instance of a piece of creosoted wood, in Lowestoft Harbour, being touched by a worm, and that was occasioned by the workmen having cut away a great part of one of the cross heads, leaving exposed the interior or heart of the wood, to which the creosote had not penetrated. At this spot a worm entered, and bored to the right, where it found creosote; on turning back and boring to the left, but finding creosote all around, its progress was stopped, and it then appeared to have left the piece of wood altogether.
In 1849, Mr. Doswell, who had the conduct of experimentson different descriptions of wood at Southampton, where the river was so full of the worm that piles of 14 inches square had been eaten down to 4 inches in four years, reported as follows: “From my examination, last spring tides, of the specimen blocks attached, on the 22nd February, 1848, to some worm-eaten piles of the Royal Pier, I am enabled to report that Bethell’s creosoted timbers all continue to be unaffected by the worms; that the pieces saturated with Payne’s solution continue to lose in substance by their ravages; and that the unprepared timbers diminish very fast, except the American elm, which stands as well (or nearly so) as that prepared by ‘Payne’s solution.’”
The following are the detailed particulars:
Bethell’s Creosoted Blocks, placed February 22, 1848.
Paynized Blocks, placed April 6, 1848.
Unprepared Blocks, placed April 6, 1848.
On 1st January, 1852, Mr. Doswell ascertained that, notwithstanding the number ofteredinesandlimnoriato be found in the Southampton Waters, none of the creosoted blocks had been attacked by them.
According to M. Forestier, similar results have been obtained at Brighton, Sunderland, and Teignmouth.
Allusion has already been made to Mr. Pritchard, of Shoreham, with reference to preserving timber. On July 26, 1842, he presented a report to the Treasurer of the Brighton Suspension Chain Pier Company, upon the preservation of timber from the action of sea-worms. We give a portion of it, as follows:
“Stockholm tar has been used, and proved to be of little service; this tar is objectionable owing to its high price, and also from its being manufactured from vegetable substances. All tars containing vegetable productions must be detrimental to the preservation of timber, especially when used in, and exposed to, salt water. This tar does not penetrate into the wood, and in a very few months the salt acid of the sea will eat it all away.
“Common gas or coal tar has been used to a great extent, and its effects are apparent to all. It does a very great deal of harm, forms a hard or brittle crust or coat on the wood, and completely excludes the damp and unnatural heat from the possibility of escape, owing to its containing ammonia, which burns the timber, and in a few years it turns brown and crumbles into dust. Indeed, timber prepared with this tar will be completely destroyed on this coast and pier by the ravages of theTeredo navalis, and theLimnoria terebrans, in five or six years.
“Also Kyan’s patent, or the bi-chloride of mercury, has been used, but has proved equally useless. The sleepers Kyanized five years ago, and in use at the West India Dock warehouses, have been discovered to decay rapidly,and the wooden tanks at the Anti-Dry-Rot Company’s principal yard are destroyed.
“I would recommend you for the future to use ‘oil of tar and pyrolignite of iron’ (Bethell’s patent). This process will, without a doubt, succeed. I have proved in hydraulic works on this coast that it will fully prevent the decay in timber piles, destroy sea-worms, and supersede the necessity of coating the piles with iron nails. In Shoreham Harbour, for instance, there is a piece of red pine accidentally infused with pyrolignite of iron, which after being in use twelve years is perfectly sound. There is another waleing piece, the very heart of English oak, Kyanized, and in use only four years, which is like a honeycomb or network, completely eaten away by theteredoand other sea-worms. I have fully proved the efficiency of this method at different harbours and docks. Sixteen years ago I had timber prepared with it, and in use on the shores of the Dee, and it is at the present moment perfectly sound. The pyrolignite of iron must be used of very pure quality; the timber must be dry; afterwards the oil of tar must be applied, and not on any account must it contain a particle of ammonia. The immense destruction on the coast of timber by the sea-worms, and the important fact that at the Chain Pier there are not twenty of the original piles remaining at the present time, is of itself sufficient to awaken anxiety.”
With regard to the opinion of foreigners on the subject of creosoting, we cannot do better than quote the report of the commission or committee (instituted in 1859) of the Royal Academy of Sciences, Holland, upon the meansof preserving wood from theteredo, published at Haarlem in 1866. It is as follows:
“To conclude, it results from experiments which the committee has directed during six consecutive years, that—
“1st. Coatings of any sort whatever applied to the surface of the timber in order to cover it with an envelop upon which the youngteredowill not fasten offer a very insufficient protection; such an envelop soon becomes damaged, either by mechanical action, such as the friction of water or ice, or by the dissolving action of water; and as soon as any point upon the surface of the wood is uncovered, however small it be, theteredoesof microscopic size penetrate into the interior of the wood.
“Covering wood with plates of copper, or zinc, or flatheaded nails are expensive processes, and only defend the wood as long as they present a perfect and unbroken surface.
“2nd. Impregnation with soluble metallic salts generally considered poisonous to animals does not preserve the wood from the invasions of theteredo; the failure of these salts is partly attributable to their being soaked out of the wood by the dissolving action of the sea-water, partly also to the fact that some of these salts do not appear to be poisonous to theteredo.
“3rd. Although we cannot venture to say that there may not be found in the colonies a wood that may resist theteredo, yet we may affirm that hardness of any timber is not an obstacle to the perforations of this mollusc. This has been proved by the ravages it has made on the Gaïac and Mamberklak woods.
“4th. The only means which can be confidently regarded as a preservative against the ravages of theteredois the creosote oil; nevertheless, in the employment of this agent great care should be taken regarding the quality of the oil, the degree of penetration, and the quality of the wood treated.”
These results of the experiments of the committee are confirmed by the experience of a large number of engineers of ponts et chaussées (bridges and causeways) in Holland, England, France, and Belgium. For example, very lately a Belgian engineer, M. Crepin, expressed himself as follows in his Report, dated 5th February, 1864, upon experiments made at Ostend:
“The experiment now appears to us decisive, and we think we may conclude that fir timber well prepared with creosote oil of good quality is proof against theteredo, and certain to last for a long time. Everything depends, therefore, upon a good preparation with good creosote oil, and on the use of wood capable of injection. It appears that resinous wood is easiest to impregnate, and that white fir should be rejected.”
M. Forestier, the able French engineer at Napoléon-Vendée sums up as follows the results of the experiments undertaken by him in the port of Sables-d’Olonne, viz.:
“These results fully confirm those obtained at Ostend, and it appears to us difficult not to admit that the experiments of Ostend and Sables d’Olonne are decisive, and prove in an incontestable manner that theteredocannot attack wood properly creosoted.”
It thus appears that there are three preservativemethods, which, according to experience, will save timber piles from the ravages of the worms, viz.: 1st. By using woods able to resist unaided their attacks. 2nd. The mechanical method, which is, by covering the piles with scupper nails, &c. This process is, however, very expensive, especially as the four sides of the pile must be covered; and, moreover, it affords no protection to the timber from internal rot or decay. 3rd. The chemical, or “creosoting” method. This process is cheaper than the last; it preserves the wood from decay, and no worms will touch it.
When unprepared piles are placed in the sea, there is every probability, sooner or later, of their being attacked by theteredo. This animal, however, is not left in peaceable enjoyment of the dwelling which it has constructed, and the food which it loves, but is liable to be attacked by an enemy, anannelide, to which the late M. de Haan has given the name ofLycoris fucata. This animal is to be found wherever theteredoexists, indeed its eggs and larva are to be met with in the midst of those of the mollusc. M. Kater has remarked that the adultlycorisdwelling in the mud which it enters during winter, and into which the piles are driven, climbs up the pile to the hole formed by theteredo, where, in some manner, it sucks or eats its victim; then having enlarged the entrance to the hole, it enters and rests in the place of theteredo. After a time it goes back to the entrance, and commences to seek for fresh prey.
Thelycorisis narrow and not very long, provided laterally with a great many little feet terminating in pointsand covered with hair, and having in front a pair of hard superior jaws, pointed horns, and the inferior jaws bent round in the form of hooks. Behind the head are four pairs of tubuliform gills. It is with these arms that this little animal pursues and devours theteredo.
One day M. Kater was fortunately able to observe the operations of thelycoris, One of these animals coming out of a hole in the wood which he inhabited, seized upon ateredo, which M. Kater had previously deposited at the bottom of the vessel containing the wood. He saw theannelideseize theteredo, hurry away with it to the hole which he occupied, and so completely devour it that he finally left only the two valves of the shell. Our illustrations of theteredoandlycorisare derived from the works of Mr. Paton and M. Forestier; and our own sketches.
If thelycoriswould only destroy theteredo, when the mollusc was in its infancy, what an invaluable little annelide it would be!
It appears to us a great pity that the woods we have named, or some of them, are not brought over to England in large quantities for harbour works. In Ceylon and India, the trees are felled by Indian wood-cutters at little cost; they are then dragged to the river banks by elephants or buffaloes, to be floated down the rivers to the different ports, so that labour is cheap. The question then remains, how to get the woods to England? When the ‘Great Eastern ship has finished carrying cables, perhaps its owners will not object to send the ship on a few voyages with heavy cargoes to India, Demerara, &c., bringing home “teredo-proof woods,”at moderate charges for freight?
Finally, to place the subject in a practical form, we think the Institute of Civil Engineers, of London, would be heartily thanked by the engineering world if they would appoint a committee to inquire into the damages done to works by sea-worms; why they are found in some parts of a roadstead or harbour, and not in others; to consider the different remedies which have been proposed, their cost, and method of application; what course should be adopted to prevent sea-water injuriously affecting iron piles; and lastly, to publish a detailed account of their experiments and recommendations.
Of the ant proper, or that belonging to the orderHymenoptera, there are three species[24]in particular which attack timber, viz.:
1st.Formica fuliginosa, or black carpenter ant, which selects hard and tough woods.
2nd.Formica fusca, or dusky ant, which prefers soft woods.
3rd.Formica flava, or yellow ant, which also prefers soft woods.
The carpenter bee prefers particular kinds of wood. In India it is very fond of cadukai (Tamil) wood, which is often used for railway sleepers. Round the holes it makes there is a black tinge, arising, probably, from the iron in its saliva acting on the gallic acid of the timber. Providing it meets with the wood it prefers, it is not very particular whether it is standing timber, or the beams of a residence.
The termite, or white ant, is a terrible destroyer of wood in nearly all tropical countries. There are many speciesof termite, and all are fearfully destructive, being indeed the greatest pest of the country wherein they reside. Nothing, unless cased in metal, can resist their jaws; and they have been known to destroy the whole woodwork of a house in a single season. They always work in darkness, and, at all expenditure of labour, keep themselves under cover, so that their destructive labours are often completed before the least intimation has been given. For example, the termites will bore through the boards of a floor, drive their tunnels up the legs of the tables or chairs, and consume everything but a mere shell no thicker than paper, and yet leave everything apparently in a perfect condition. Many a person has only learned the real state of his furniture by finding a chair crumble into dust as he sat upon it, or a whole staircase fall to pieces as soon as a foot was set upon it. In some cases the termite lines its galleries with clay, which soon becomes as hard as stone, and thereby produces very remarkable architectural changes. For example, it has been found that a row of wooden columns in front of a house have been converted into a substance as hard as stone by these insects. In pulling down the old cathedralat Jamaica, some of the timbers of the roof, which were of hard wood, were eaten away, and a cartload of nests formed by the ants was removed, after being cut away by great labour with hatchets.
The first indication of a house being attacked by ants in the tropics is, perhaps, the yielding of a floor board in the middle of a room, or the top hinge of a door suddenly leaving the frame to which it had been firmly screwed a short time before.
That the ants provide for winter—as not only Dr. Bancroft and many others, even King Solomon, reports—is found to be an error. Where there is an ordinary winter, the ants lie dormant, during which torpid state they do not want food.
The greater number of species belong to the tropical regions, where they are useful in destroying the fallen trees that are so plentiful in those latitudes, and which, unless speedily removed, might be injurious to the young saplings by which they are replaced. Two species, however, are known in Europe, namely,Termes lucifugusandTermes rucifollis, and have fully carried out their destructive character, the former species devouring oaks and firs, and the latter preferring olives and similar trees.At La Rochellethese insects have multiplied so greatly as to demand the public attention.
M. de Quatrefages, who visited one of the spots in which these destructive insects had settled themselves, gives the following account of their devastating energy: “The prefecture and a few neighbouring houses are the principal scene of the destructive ravages of the termites, but here they have taken complete possession of the premises. In the garden not a stake can be put into the ground, and not a plank can be left on the beds, without being attacked within twenty-four or forty-eight hours. The fences put round the young trees are gnawed from the bottom, while the trees themselves are gutted to the very branches.
“Within the building itself the apartments and offices are all alike invaded. I saw upon the roof of a bedroom that had been lately repaired galleries made by the termiteswhich looked like stalactites, and which had begun to show themselves the very day after the workmen left the place. In the cellars I found similar galleries, which were either half way between the ceiling and the floor, or running along the walls and extending, no doubt, up to the very garrets, for on the principal staircase other galleries were observed, between the ground floor and the second floor, passing under the plaster wherever it was sufficiently thick for the purpose, and only coming to view at different points where the stones were on the surface, for, like other species, the termites of La Rochelle always work under cover wherever it is possible for them to do so. It is generally only by incessant vigilance that we can trace the course of their devastations and prevent their ravages.
“At the time of M. Audoin’s visit a curious proof was accidentally obtained of the mischief which this insect silently accomplishes. One day it was discovered that the archives of the department were almost totally destroyed, and that without the slightest external trace of any damage. The termites had reached the boxes in which these documents were preserved by mining the wainscoting, and they had then leisurely set to work to devour these administrative records, carefully respecting the upper sheets and the margin of each leaf, so that a box which was only filled by a mass of rubbish seemed to enclose a file of papers in perfect order.
“The hardest woods are attacked in the same manner. I saw on one of the staircases an oak post, in which one of the clerks had buried his hand up to the wrist in graspingat it for support, as his foot accidentally slipped. The interior of the post was entirely formed of empty cells, the substance of which could be scraped away like dust, while the layer that had been left untouched by the termites was not thicker than a sheet of paper.”
It is most probable that these insects had been imported from some vessel, as they attacked two opposite ends of the same town, the centre being untouched. M. de Quatrefages tried many experiments on these insects with a view of discovering some method of destroying them, and came to the conclusion that ifchlorinecould be injected in sufficient quantities, it would in time have the desired result.
The termite or white ant is represented by Linnæus as the greatest pest of both Indies, because of the havoc they make in all buildings of wood, in utensils, and in furniture. They frequently construct nests within the roofs and other parts of houses, which they destroy if not speedily extirpated. The larger species enter under the foundations of houses, making their way through the floors and up the posts of buildings, destroying all before them; and so little is seen of their operations that a well-painted building is sometimes found to be a mere shell, so thin that the woodwork may be punched through with the point of the finger.
Many kinds of woodin Brazil[25]are impervious to the termite, which insect generally selects the more porouswoods, and especially if these are in contact with the earth. In dry places, and witha free circulation of air, it does not prefer timber thus situated; and it is found that roofs of buildings ofgoodand well-seasoned native wood resist for an indefinite period both the climate and the termite. As a general rule, Brazilian timber is very brittle.
It shows the difference of effects between one climate and another, that in Brazil the more porous and open-grained timbers are most subject to the attacks of the white ant, especially if they are in contact with the earth; butin Australiait is the reverse, for there it is the hardest description of timber that those insects first attack. There is one wood in particular, in common use, to which this remark applies, namely, “Iron Bark.” Its density is so great that it sinks in water, and its strength is extraordinary, and yet the wood the white ants are particularly fond of. In the West Indies, the ants prefer hard woods.
At Bahia, the timber is less affected by the termite thanin Pernambuco; but even in the latter place the white ant does not like dry places with a free circulation of air.
Mr. Shields, when on a short visit to Pernambuco, examined some timber bridges, and in one, which had only been constructed three years, he found the ends of the timber had been placed in contact with the moist clay; at those places he could readily knock off the crust of the wood, and the interior of the wood was almost filled with white ants: the decay was augmented by the contact of the wood with the moist clay. We have beeninformed that timber for the Government works is stored to the depth of about 1 foot 6 inches in the sea-sand, to protect it from the white ants and theteredo; and that in Pernambuco, since the establishment of the gas-works, the Brazilian engineers and constructors “pay” over the ends of all timbers used in buildings with coal-tar.
In Ceylon, no timber—except ebony and ironwood, which are too hard; palmyra, innorthernCeylon; and those which are strongly impregnated with camphor or aromatic oils, which they dislike—presents any obstacle to their ingress. Sir Emerson Tennant, in his work on Ceylon, says: “I have had a cask of wine filled, in the course of two days, with almost solid clay, and only discovered the presence of the white ants by the bursting of the corks. I have had a portmanteau in my tent so peopled with them in the course of a single night that the contents were found worthless in the morning. In an incredibly short time a detachment of these pests will destroy a press full of records, reducing the paper to fragments; and a shelf of books will be tunnelled into a gallery, if it happened to be in their line of march.”
In Ceylon, the huts are plastered over with earth, which has been thrown up by white ants, after being mixed with a powerful binding substance (produced by the ants themselves), and through which the rain and moisture cannot penetrate. This will hold the walls together when the entire framework and the wattles have been eaten, or have become decayed.
In the Philippine Islands, ambogues, a strong, durable wood, suffers much from the termites. Sir John Bowring,in his work on these islands, thus writes of the ravages of the white ants in the town of Obando, Province of Bulacan, Philippine Islands: “It appears that on the 18th March, 1838, the various objects destined for the services of the mass, such as robes, albs, amices, the garments of the priests, &c., were examined, and placed in a trunk made of the wood called ‘narra’ (Pterocarpus palidus). On the 19th they were used in the divine services, and in the evening were restored to the box. On the 20th some dirt was observed near it, and, on opening it, every fragment of the vestments and ornaments of every sort were found to have been reduced to dust, except the gold and silver lace, which were tarnished with a filthy deposit. On a thorough examination not an ant was found in any other part of the church, nor any vestige of the presence of these voracious destroyers; but five days afterwards they were discovered to have penetrated through a beam 6 inches thick.”
The red antin Batavia(north-west end of Java) is another devastator. The red ant contains formic acid (acid of ants) and a peculiar resinous oil. Thunberg[26]has found cajeput effectual in destroying the red ants of Batavia: he used it to preserve his boxes of specimens from them. When ants were placed in a box anointed with this oil, they died in a few minutes.
In Surinam, Guiana, several species of worms are produced in the palm-trees as soon as they commence to rot: they are called “groo-groo,” and are produced from the spawn of a black beetle; they are very fat, and grow tothe size of a man’s thumb. The groo-groo will very quickly destroy wood which has commenced to rot.
In Surinam, Captain Stedman[27]was obliged to drive nails into the ceiling of his room, and hang his provisions from the nails; he then made a ring of dry chalk around them, very thick, which crumbled down the moment the ants attempted to pass it. In Guiana, the young ants will swim across a small pool of water to get at sugar; some get drowned, the rest get the sugar.
In Japan, according to Kœmpfer,[28]ants do considerable damage to wood.
In Senegal, the ant (Termite belliqueux) is a formidable agent of destruction. In a season, all the carpentry of a house is destroyed by them. Spartimann, in his ‘Voyage to the Cape of Good Hope,’[29]gives an excellent account of their methods of working.
TheTermite lucifugehas been discovered in the environs ofBordeaux, in the pine-trees; also in the marine workshops atRochefort. It is believed to have been imported from America.
TheTermite flavicole, a few years since, attacked the olive-trees ofSpain, and it occasionally visits the centre ofFrance.
White or yellow pine wood can only be used in the tropics for doors, movable window frames, bodies of railway waggons, or other work intended to be kept in motion. Its use even for these purposes is questionable, as thewhite ant has such an affinity for it, that a door or a window which has remained shut for a few weeks will almost invariably be attacked by that insect.
North American pitch pine withstands very well the attacks of the termite, when used in the roofs of buildings, or in any locality not humid; but it is found after a time, when laid upon the earth, to lose its resisting powers, as well as to become subject to rapid decay.
“Greenheart” timber in its natural state is proof against the attacks of this insect in tropical climates—especially that known as the “purple-heart” wood. There are two reasons why it enjoys this immunity from attack: first, there is its great hardness; and, secondly, there is the presence of a large quantity of essential oil. It is very hard and durable wood; a little heavier than water. It is obtained at Demerara.[30]Great care is required in working it, as it is very liable to split. In sawing it is necessary to have all the logs bound tightly with chains, failing which precaution the log would break up into splinters, and be very apt to injure the men working it.
“Jarrah” wood, from Australia, is also proof against the attacks of the white ant. It is occasionally liable to shakes.
“Panao” wood, from the Philippine Islands, gives the talay oil, which destroys insects in wood.
“Bilian” wood is imported to Bombay, from Sarawak,Borneo. This wood is impervious to the attacks of the termite, and does not decay when under fresh or salt water, where it remains as hard as stone.
“Sál” wood, in India, is occasionally touched by the white ant. This wood, however, requires two years to season, and it will twist, shrink, and warp whenever the surface is removed, after many years’ seasoning. Only about 2 lb. of creosote oil per cubic foot can be injected into sál wood. “Kara-mardá” is avoided by this little insect; but when used for planks it requires twelve to fifteen months’ previous seasoning. “Neem-wood,” used for making carved images, enables an image to remain undisturbed by the white ant.
The following is a list of woods which resist for a long time, if not altogether, the attacks of the termites, or white ants: