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Partitions and minor timbers: American red wood or red pine, which not being so strong as that from the Baltic, must be cut to a little larger size.

Sleepers, window sills, and some parts of the roof: Oak.

Framing: Norway and Christiania white deals; Christiania yellow deals are sappy; Swedish deals are bad, as they warp much.

Panelling: Christiania white pine; or American yellow pine.

Best ordinary floors: Drammen and Christiania white deals; American pitch pine; American deals are bad for floors, as they are a softer wood.

Ground floors: Stockholm and Gefle yellow deals.

Warehouse floors, and Staircases: Archangel and Onega planks, and American pitch pine. Best floors: Petersburgh, Onega, and Christiania battens.

Interior finishings generally: Baltic red and white wood, and American red and yellow pine. 1729g. Memel timber is generally considered the most convenient for size, and is superior in strength to the Swedish, or Norwegian; Riga, the best in quality; Dantzic, when free from large knots, the strongest; and the Swedish, the toughest, but weakest, Riga can always be depended upon, and although the dearest in price, is the cheapest in the end.

1730. We shall now place before the reader, observations on timber made by the cele brated Evelyn though perhaps at the risk of repetition in what follows after them.

1731. “Lay up your timbers very dry, in an airy place, yet out of the wind or sun, and not standing very upright, but lying along, one piece upon another, interposing some short blocks between them, to preserve them from a certain mouldiness which they usually contract while they sweat, and which frequentiy produces a kind of fungus, especially if there be any sappy parts remaining.

1732. "Some there are yet who keep their timber as moist as they can by submerging it in water, where they let it imbibe, to hinder the cleaving; and this is good in fir, both for the better stripping and seasoning; yea, not only in fir, but other timber. Lay, therefore, your boards a fortnight in the water (if running the better, as at some mill-pond head); and there, setting them upright in the sun and wind, so as it may freely pass through them (especially during the heats of summer, which is the time of finishing buildings), turn them daily; and thus treated, even newly sawn boards will floor far better than many years' dry seasoning, as they call it. But, to prevent all possible accidents, when you lay your floors, let the joints be shot, fitted, and tacked down only for the first year, nailing them for good and all the next; and by this means they will lie staunch, close, and without shrinking in the least, as if they were all one piece. And upon this occasion I am to add an observation, which may prove of no small use to builders, that if one take up deal boards that may have lain in the floor a hundred years, and shoot them [plane their edges] again, they will certainly shrink (toties quoties) without the former method. Amongst wheelwrights the water seasoning is of especial regard, and in such esteem amongst some, that I am assured the Venetians, for their provision in the arsenal, lay their oak some years in water before they employ it. Indeed, the Turks not only fell at all times of the year. without any regard to the season, but employ their timber green and unseasoned ; so that though they have excellent oak, it decays in a short time, by this only neglect.

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1733. Elin felled ever so green, for sudden use, if plunged four or five days in water (especially salt water), obtains an admirable seasoning, and may immediately be used. I the oftener insist on this water seasoning, not only as a remedy against the worm, but for its efficacy against warping and distortions of timber, whether used within or exposed to the air. Some, again, commend burying in the earth; others in wheat; and there be seasonings of the fire, as for the scorching and hardening of piles, which are to stand either in the water or in the earth.

1734. "When wood is charred it becomes incorruptible; for which reason, when we wish to preserve piles from decay, they should be charred on their outside. Oak posts used in enclosures always decay about two inches above and below the surface. Charring that part would probably add several years to the duration of the wood, for that to most timber it contributes its duration. Thus do all the elements contribute to the art of seasoning.

1735. Timber which is cleft is nothing so obnoxious to reft and cleave as what is hewn; nor that which is squared as what is round: and therefore, where use is to be made of huge and massy columns, let them be bored through from end to end. It is an excellent preservative from splitting, and not unphilosophical; though to cure the accident painter's putty is recommended; also the rubbing them over with a wax cloth is good; or before it be converted the smearing the timber over with cow-dung, which prevents the effects both of sun and air upon it, if of necessity it must lie exposed. But, besides the forner remedies, I find this for the closing of the chops and clefts of green timber, to anoint and supple it with the fat of powdered beef broth [we do not quite agree with our author here], with which it must be well soaked, and the chasms filled with sponges dipped into it. This to be twice done over.

1736. "We spake before of squaring; and I would now recommend the quartering of such trees as will allow useful and competent scantlings to be of much more durableness and effect for strength, than where (as custom is and for want of observation) whole bes.ns and timbers are applied in ships or houses, with slab and all about them, upon false suppo sitions of strength beyond these quarters.

1737. "Timber that you have occasion to lay in mortar, or which is in any part cɔntiguous to lime, as doors, window cases, groundsils, and the extremities of beams, &c., nave sometimes been capped with molten pitch, as a marvellous preserver of it from the burning and destructive effects of the lime; but it has since been found rather to heat and decay them, by hindering the transudation which those parts require; better supplied with loam, or strewings of brick-dust or pieces of boards; some leave a small hole for the air. But though lime be so destructive, whilst timber thus lies dry, it seems they mingle it with hair to keep the worm out of ships, which they sheathe for southern voyages, though it is held much to retard their course.

1738. " For all uses, that timber is esteemed the best which is the most ponderous, and which, lying long, makes the deepest impression in the earth, or in the water being floated; also what is without knots, yet firm and free from sap, which is that fatty, whiter, and softer part called by the ancients albumen, which you are diligently to hew away. My Lord Bacon (Exper. 658.) recommends for trial of a sound or knotty piece of timber, to cause one to speak at one of the extremes to his companion listening at the other; for if it be knotty, the sound, says he, will come abrupt."

PRESERVATION OF TIMBER.

1739. The preservation of timber, when employed in a building, is the first and most important consideration. Wherever it is exposed to the alternations of dryness and moisture, the protection of its surface from either of those actions is the principal object, or, in other words, the application of some substance or medium to it which is imperviable to moisture; but all timber should be perfectly dry before the use of the medium. In Holland the application of a mixture of pitch and tar, whereon are strewn pounded shells, with a mixture of sea sand, is general; and with this, or small and sifted beaten scales from a blacksmith's forge, to their drawbridges, sluices, and gates, and other works, they are admirably protected from the effects of the seasons. Semple, in his work on aquatic building, recommends, that "after your work is tried up, or even put together, lay it on the ground, with stones or bricks under it to about a foot high, and burn wood (which is the best firing for the purpose) under it, till you thoroughly heat, and even scorch it all over; then, whilst the wood is hot, rub it over plentifully with linseed oil and tar, in equal parts, and well boiled together, and let it be kept boiling while you are using it; and this will immediately strike and sink (if the wood be tolerably seasoned) one inch or more into the wood, close all the pores, and make it become exceeding hard and durable, either under or over water." Semple evidently supposes the wood to have been previously well seasoned.

1740. Chapman (on the preservation of timber) recommends a mixture of sub-sulphate of iron, which is obtained in the refuse of copperas pans, ground up with some cheap oil, and made sufficiently fluid with coal-tar oil, wherein pitch has been infused and mixed.

1741. For common purposes, what is called sanding, that is, the strewing upon the painting of timber, before the paint dries, particles of fine sand, is very useful in the preservation of timber.

1742. Against worms we believe nothing to be more efficacious than the saturation of timber with any of the oils; a process which destroys the insect if already in the wood, with that of turpentine especially, and prevents the liability to attack from it. Evelyn recommends nitric acid, that is, sulphur immersed in aquafortis and distilled, as an effectual application. Corrosive sublimate, lately introduced under Kyan's patent, has long been known as an effectual remedy against the worm. Its poisonous qualities of course destroy all animal life with which it comes in contact; and we believe that our readers who are interested in preserving the timbers of their dwellings may use a solution of it without infringing the rights of the patentee. But the best remedy against rot and worms is a thorough introduction of air to the timbers of a building, and their lying as dry and as free from moisture as practicable. Air holes from the outside should be applied as much as possible, and the ends of timbers should not, if it can be avoided, be bedded up close all round them. This practice is, moreover, advisable in another respect, that of being able, without injury to a building, to splice the ends of the timbers should they become decayed, without involving the rebuilding of the fabric; a facility of no mean consideration.

1743. The worm is so destructive to timber, both in and out of water, that we shall not apologise for closing this part of our observations with Smeaton's remarks upon a species of worm which he found in Bridlington piers. "This worm appears as a small white soft substance, much like a maggot; so small as not to be seen distinctly without a magnifying ass, and even then a distinction of its parts is not easily made out. It does not attempt

to make its way through the wood longitudinally, or along the grain, as is the case with the common ship worm, but directly, or obliquely, inward. Neither does it appear to make its way by means of any hard tools or instruments, but rather by some species of dissolvent liquor furnished by the juices of the animal itself. The rate of progression is, that a three inch oak plank will be destroyed in eight years by action from the outside only." For resisting the effects of these worms, Smeaton recommends the piles to be squared, to be fitted as closely as possible together, and to fill all openings with tar and oakum, to make the face smooth, and cover it with sheathing.

1744. The destructive effects of the white ant are so little known here, that it is unnecessary to make further mention of them, than that in India they are the most inveterate enemies with which timber has to contend. From Young's Annals we extract the following curious statement of experiments made upon inch and a half planks, from trees of thirty to forty-five years' growth, after an exposure of ten years to the weather.

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Whence we may be led to some inference of the value of different sorts of timber in resisting weather; though we must not be altogether guided by the above table, inasmuch as it is well known that the soil on which timber is grown much increases or deteriorates its value, and that split timber is more durable and stronger than that which is sawn, from the circumstance of the fibres, on account of their continuity, resisting by means of their longitudinal strength; whereas when severed by the saw, the resistance depends more on the lateral cohesion of the fibres. Hence whole trees are invariably stronger than specimens, unless these be particularly well selected, and of a straight and even grain; but in practice the results of experiments are on this account the more useful.

DECAY OF TIMBER.

1745. If timber, whatever its species, be well seasoned, and be not exposed to alternate dryness and moisture, its durability is great, though from time it is known to lose its elastic and cohesive powers, and to become brittle if constantly dry. On this account it is unfit, after a certain period, to be subjected to variable strains: however, in a quiescent state it might endure for centuries. Dryness will, if carried to excess, produce this category. The mere moisture it absorbs from the air in dry weather is not sufficient to impair its durability. So, also, timber continually exposed to moisture is found to retain for a very long period its pristine strength. Heat with moisture is extremely injurious to it, and is in most cases productive of rot, whereof two kinds are the curse of the builder, the wet and the dry rot, though perhaps there be but little difference between the two. They appear to be produced by the same causes, excepting that the freedom of evaporation determines the former, and an imperfect evaporation the latter. In both cases the timber is affected by a fungus-like parasite, beginning with a species of mildew; but how this fungus is generated is still a vexata quæstio; all we know is, that its vegetation is so rapid, that often before it has arrived at its height, a building is ruined. From our inquiries on the Continent, we believe the disease does not occur to the extent that it does in this country; a fact which we are inclined, perhaps erroneously, to attribute to the use of the timber of the country, instead of imported timber. Our opinion may be fanciful, but there are many grounds on which we think that is not altogether the case. Our notion is, that our imported timber is infected with the seeds of decay long before its arrival here (we speak of fir more especially), and that the comparative warmth and moisture of the climate bring more effectually the causes of decay into action, especially where the situation is close and confined. Warmth is, doubtless, known to be a great agent in the dry rot, and most especially when moisture co-operates with it, for in warm cellars and other close and confined situations, where the vapour which feeds the disease is not altered by a constant change of air, the timbers are soon destroyed, and become perfectly decomposed.

1746. The lime, and more especially the damp brickwork, which receive the timbers of a new building, are great causes of decay to the ends of them; but we do not think that the regulations of the 19 Car. II. cap. 3., which directed the builders after the fire of London, to bed the ends of their girders and joists in loam instead of mortar, would, if followed out in the present day, be at all effective in preventing the decay incident to the ends of timbers. Timber, in a perfectly dry state, does not appear to be injured by dry line; and indeed, lime is known to be effectual in the protection of wood against worms. Timber in contact with masonry is constantly found to decay, when the other parts of the

beam have been sound. This will be entirely obviated by inserting the wood in an iron shoe, or by placing a thin piece of iron betwixt the wood and the stone. Cases are known in which the iron shoe appeared to have proved a complete protection against dry rot and decay; a hard crust being formed on the timber in contact with the metal. The system of prouting must contribute to the early decay of wood bond; but at Manchester, where it was used very generally, it appeared to answer well, for the high temperature kept up in the buildings may cause the walls to dry very soon. Sea-sand, used for outside and inside purposes, in a spirit of economy, soon shows the result by inducing the appearance of rot in timber. Wood laid in sandy soil is well preserved, as was found to be the case in the specimens lately dug up at Birkenhead from depths varying from 8 feet to 32 feet; they were considered to have been buried for centuries.

1747. Nothing is more injurious to the floors of a building than covering them with painted floorcloth, which entirely prevents the access of atmospheric air, whence the dampness of the boards never evaporates; and it is well known that oak and fir posts have been brought into premature decay by painting them before their moisture had evaporated; whilst in the timber and pewing of old churches, which have never been painted, we see them sound after the lapse of centuries. Semple, in his Treatise on Building in Water, notices an instance of some field gates made of the fir of the place, part whereof, near the mansion, were painted, and had become rotten, while those more distant from the mansion, which had never been painted, were quite sound.

1747a. According to Baron Liebig, the decay of wood takes place in the three following modes:-I. The oxygen in the atmosphere combines with the hydrogen of the fibre, and the oxygen unites with the portion of carbon of the fibre, and evaporates as carbonic acid; this process is called decomposition. II. The actual decay of the wood which takes place when it is brought in contact with rotting substances. And III. The inner decomposition of the wood in itself, by losing its carbon forming carbonic acid gas, and the fibre under the influence of the latter is changed into white dust; this is called putrefaction.

PREVENTION OF DECAY.

1748. After timber is felled, the best method of preventing decay is the immediate removal of it to a dry situation, where it should be stacked in such a manner as to secure a free circulation of air round it, but without exposure to the sun and wind, and it should be rough squared as soon as possible. When thoroughly seasoned before cutting it into scantlings it is less liable to warp and twist in drying. The ground about its place of deposit should be dry and perfectly drained, so that no vegetation may rise on it. Hence a timber yard should be strewed with ashes, or the scales from a foundry or forge, which supply an admirable antidote to all vegetation. It is thought that the more gradually timber is seasoned the greater its durability; and as a general rule, it may be stated, that it should not be used till a period of at least two years from its being felled, and for joiners work at least four years. Much, however, is dependent on the size of the picces. By some water seasoning has been recommended; by others the steaming and boiling it; smoke drying, charring, and scorching have also been recommended. The latter is, perhaps, the best for piles and other pieces that are to stand in the water or in the ground. It was prac tised by the ancients, and is still in use generally for the posts of park paling and the like 1749. In Norway the deal planks are seasoned by laying them in salt water for three of four days, when newly sawed, and then drying them in the sun, a process which is con sidered to be attended with advantage; but it does not prevent their shrinking. Mr. Evely recommends the water seasoning for fir.

1749a. The effectual seasoning obtained by Davison and Symington's patent process o forcing heated air in a continued current through timber under pressure, effectually drie it, and coagulates the albumen. The timbers for the flooring of the Coal Exchange a London have been so treated, and show no signs of shrinkage. The wood was taken in it natural state, and in less than ten days it was thoroughly seasoned; in some cases from 1 to 48 per cent of moisture was taken out of it. The air when heated to about 110° or 120 is sent through the timber at a rate of about 48 miles per hour; the heat being regulate according to the quality of the timber. Honduras mahogany exposed to a heat of 300° would have the whole of the moisture taken from it in 48 hours. This process, howeve sometimes splits the timber. Out of a hundred specimens of wood experimented upor varying from one inch to twelve inches square, not one of them split: even some opening which were visible before the process was applied, were found to be closer after it. Perhap 9 inches square is the limit to which the operation can be successfully applied.

1750. Notwithstanding, however, all care in seasoning, when timber is employed in damp situation it soon decays; and one of the principal remedies against that is goo drainage, without which no precautions will avail. It is most important to take care tha earth should not lie in contact with the walls of a building. for the damp is quickly con municated, in that case, by their means to the ends of timbers, and rot soon follows. xpedient to guard against this contingency is so good as what are called air drains.

1751. When the carcass of a building is complete, it should be left as long as possible to dry, and to allow to the timbers what may be called a second seasoning. The modern practice of finishing buildings in the quickest possible period, has contributed more to dry rot than perhaps any other cause; and for this the architect has been blamed instead of his employer, whose object is generally to realize letting or to enjoy occupation of them as early as possible. After the walls and timbers of a building are once thoroughly dry, all means should be employed to exclude an accession of moisture, and delay is then prejudicial. 1752. Among the many inventions to preserve wood from decay, those of England have proved the most successful. In 1737 a patent was granted to Mr. Emerson to prepare timber with hot oil. This was followed by various recommendations early in the present century; those of later date consist of:-I. Kyan's process, 1832, who steeped the timber in a solution of bichloride of mercury, known as corrosive sublimate (par. 1742.) It appears to penetrate fir less than some other woods (Faraday). The wood thus treated becomes of less specific gravity, less flexibility, and more brittle. II. Sir William Burnett's patent of 1836, was for using the chloride of zinc. III. M. Bréant in 1837 suggested sulphate of iron, which was found not to alter the qualities of the timber as did the corrosive sublimate. IV. Margary's patent, 1837, is for steeping timber in a solution made of one pound of sulphate of copper with eight gallons of water. Wood impregnated with sulphate of copper (blue vitriol) will not last longer in sea water than any other wood. But wood so treated will last longer in the soil than if either tarred or charred. Its application for the prevention of rot is beneficial, and it might be used where not exposed to the action of water, on account of the solubility of the salts. The proportion of the sulphate should be one pound to four gallons of water; we have also met with the proportion of one pound to two gallons; perhaps the strongest is the best (par. 1752b.) V. Payne, 1841, patented a system for using two solutions; first, sulphate of iron, which would form an oxide of iron in the cells; and secondly, carbonate of soda: some very good results were obtained, but the process must be done under pressure and with the greatest care.

17524. VI. Bethell's patent, 1838, consistz in the injection of oil of tar, containing creasote and a crude solution of acetate of iron, commonly called pyrolignite of iron, after the air in the wood has been extracted. This process is effective to a great extent, and full particulars are given by G. R. Burnell in his paper read before the Society of Arts 1860, from which we have been quoting. It, however, can only be recommended for railways and other large works; the offensive smell and increased danger by fire should deter its use in house building. In the best creasoting works, the oil is injected at a temperature of 120° and under a pressure of 150 lbs. on the square inch, so that ordinary fir timber absorbs 10 lbs. weight of the creasote per cubic foot; the wood should be weighed to ascertain that it did absorb that quantity. For all engineering purposes, fir timber thus treated is far more durable than the best oak, teak, or other hard woods, and the cost of the operation is very small. Timber which has just been taken out of water contains so large a quantity that it resists the entrance of the oil; unless time, therefore, be given for it to be first dried, it would necessarily be badly prepared.

17526. VII. Dorsett and Blythe, 1863, patented the injection of heated solutions of sulphate of cop:er (par. 1752, IV.), a process said to have been adopted by French, Spanish, Italian, and other railway companies. Amongst its advantages, they state that wood so prepared is rendered to a great extent incombustible; and that for out-door purposes it has a clean yellowish surface, without odour, requires no painting, remaining unchanged for any length of time.

1752c. Experience of the English processes shows that creasoting is the most generally successful; the application of the sulphate of copper is satisfactory in many cases; while the other processes, although no doubt of occasional value, have been practically abandoned. They all depend for their success upon the skilful and conscientious manner in which the are applied; for as they involve chemical actions on a large scale, their efficiency must depend upon the observation of the minute practical precautions required to exclude any disturbing causes.

1752d. Carbolineum Avenarius is said (1887) to be an efficient preservative of wood against all external and internal injurious influence s, driving the moisture out of it by making it impervious to damp, and is stated to be a preservative against the attack of white ants in hot climates. Being thin and liquid it Boaks into the wood readily. One gallon will cover from 30 to 50 square yards.

1753. It is no easy matter to cure the dry rot where it has once taken root. If it be found necessary to substitute new timbers for old ones, every particle of the fungus, known as the Merulius lacrymuns, must be removed from the neighbourhood of such new timbers. After scraping it from the adjoining walls and timbers, perhaps no better application than one of the washes above mentioned can be employed. About 300° of heat would effect the same purpose, but this is difficult in application. Coal tar has been found useful, but its odour, arising at a moderate degree of heat, is an objection to its use. A weak solution of vitriolic acid with water will generally stop the rot if it have not gone too far. Pyroligneous acid is recommended for preventing the spreading of the disease. The precautions indicated above for the prevention of decay, although not always successful, must be deemed preferable to the application of after remedies.

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