DUN
309
DUN
*• ev;,j d<dl are first infected with the rot, the cause of whichf?etie ra | < f nt ’ as those parts that are between tlie beams are^ *i uite sound. Sixthly'-, in the beams of ships the^eci,j e , asu ally commences in the internal parts, which ist'fep ar j y °'ving, in my opinion, to the erroneous method of80 t , n ° *^6 timber, as before-mentioned ; but when timber,s 0 r e<1 ' is used, I would recommend, as the best preven-at) , le rot, that a few holes be bored through the beama hotl ler , aPt > an d, what would still add to the benefit, to bore8f e bor e lengthways of the grain, to meet those which• w cross ' va y s - But the best preventive, I am con-NbeJ. be the adoption of my mode of preparing the
“7 \vl,j’r' z '> to saw it lengthways right through the heart,S r fcat e n °t only greater durability would be obtained, butThJ^my in the consumption of the timber.”
' Vf ittg ri ® as we have before observed, volumes have beenthe subject of dry-rot, the causes of it are still,Jr. ’ 88 little understood as ever ; and, as was stated bye }% of Leeds, in a paper read to the Society for the
e Xtw ernent °f Arts, &c., “ to bring the matter to the test
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the
.. <ll selected situations.” “ Wood used for _
Nt PUr ?° Sfts °f m an >” be observes, “is cut down at‘Soti, i* er '°ds ; and although it may be felled at the proper
g'^ys to' i' v * len most free from sap or moisture, it is not;«t dovy.^ . effected. Nay, even admitting it to have beenf ’ l b 8 . ln the most favourable situation, it still aboundsi^Sular ey„ an extra proportion of moisture, as to require a
t wixlf° SUre to 4 b e a ‘ r prior to its being applied to use,■ Plac *° S uai 'd against that shrinking which alwayse where this precaution has not been taken. And
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% ISl *refj] 6 ® r ~kind contains less of this watery portion, yetRe es > b ^ ^° saess es a considerable share ; and it is in thisit ■'^Hy 6 "^Prebends, that the evil, called the dry-rot , mostas, from the facility of working the same,w be ( 5 P generally applied to buildings. But, supposing itt|, a Hy e ° r an y other species, wood felled when aboundingC Pro Per* tra P ro P°rtion of sap, and applied to use without’■ ’1 8 easonintr or exposure to a free current of air,
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ti^*d 0ll ] a S a >nst it, would be the precaution of felling allSR^^tiori N! le proper season, or when the sap is not in
e xti'a moisture has had time to exhale, is most
f; Htj 0n le disease in question ; and the cure, or principal
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to W 00( j A ‘*e next mode of prevention would be to use
^0 inf],. n v as has been for a considerable period exposedii, ? Win j 10 ? °f a free current of air, or, where conveni-to f 1 tit g X( . nilt > to that of air heated to a moderate degree;\’ an d i n !° tln g, with greater facility, the enclosed mois-’bfPWe a more certain ratio than the irregularity of ourttw.'s ij n 1 ' allow under other circumstances.”fij f lfs of t |° *bc place for examining into the comparative. ®" eren t processes which have been introducedt> t’mher. The most noted of these are Kvan’s,' N%l\. Ne’s
ll i s Mt)e d by J7 n . e s ’ an d Bethell’s, all of which have been^fitcien* le ' r advocates as perfect preventives of dry-rot;(j i 4 y _ v e a j s to »ay, that they have all been found successful,pinion f ;„ a " Whiled. The best preventive of dry-rot, in
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8r led ’ *? have the timber thoroughly dry before
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it is
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nylPleteci' to i et plenty of air get to it when the buildin.
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ln bricklaying, is replacing and making
ea yed brickwork, when the wall is to be
”', B CRGH, th, nam, of on metal: mecta of'Cl od’Ll 8 cil 'cular form, common in the Orkney and■ Th! , ds > ‘fie Hebrides , and northern parts of bcot-latter term points out the founders, who at the4 K
same time bestowed on them their natal name of borg, “ adefence or castle,” a Suco-Gothic word ; and the Highlandersuniversally apply to these places the Celtic name dun , signify-ing a hill defended by a tower, which plainly points outtheir use. They are confined to the countries once subjectto the crown of Norway . With few exceptions, they arebuilt within sight of the sea, and one or more within sight ofthe other ; so that on a signal by fire, by flag, or by trumpet,they could give notice of approaching danger, and yield amutual succour. In the Shetland and Orkney islands, theyare most frequently called wart or ward hills, which showsthat they were garrisoned. They had their wardmadher, orwatchman, a sort of sentinel, who stood on the top, andchallenged all who came in sight. The gackman was anofficer of the same kind, who not only was on the watchagainst surprise, but was to give notice if he saw any shipsin distress. He was allowed a large horn of generous liquor,which he had always by him, to keep up his spirits. Alongthe Orkney and Shetland shores, they almost form a chain ;and by that means not only kept the natives in subjection,but were situated commodiously for covering the landing of Itheir countrymen, who were perpetually roving on piraticalexpeditions. These towers were even made use of as stateprisons ; for we learn from Torfaeus, that after Sueno had !surprised Paul, count of Caithness, he carried him intoSutherland, and confined him there in a Norwegian tower.Out of our own kingdom, no buildings similar to these '•are to be found, except in Scandinavia . On the mountainSwalherg in Norway is one ; the Stir-biskop, at Upsal inSweden , is another ; and Umseborg, in the same kingdom,is a third.
In these buildings, there is no appearance of an arch ; thewall, which consists of the best flat stones the workman couldfind, is well laid, is in thickness about 14 feet, and in someinstances not more than 12 feet high ; the structure of a dunis upon ‘a circular plan, about 20 or 30 feet in diameter.The door of entrance is very low, and was shut up occasion-ally with a broad flat stone. In some instances, where thestones were not flat or well bedded, the wall is found proppedup with heaps of stones, like buttresses, on the outside ; soas to give the whole more the appearance of a mount, thanof a building, as is particularly the case with one at Loth-beg, ni the parish of Lothis. The most entire dun is that atGlenby, not far from Inverness , and described by Mr. Pen-nant, in his voyage to the Hebrides ; from whose verycurious and original account, the following particulars areextracted :— j
“It is placed about two miles from the mouth of the !valle}'. The more entire side is about thirty feet sixinches in height, and was, some years ago, about ten feethigher. The whole structure appears to have been, on theoutside, of a conical form ; but on the inside, the surround- iing wall is quite perpendicular ; so that it must have beenmuch thicker at the bottom than at the top. It enclosed asmall circular area of thirty-three feet and a half in diameter ;and was constructed merely of flat stones neatly placed oneupon another, without any cement or mortar. At ten feetfrom the ground it was found to be seven feet four inchesthick : and within this thickness were two surroundinggalleries ; one quite in the lower part of the tower, about sixfeet two inches high, and two feet five inches wide at thebottom ; but made narrower at the top ; and flagged and :covered with great flat stones. And the other gallery was jplaced directly over this, having these flag-stones for its |floor, and being only five feet six inches high, and only |twenty inches wide at the bottom ; but covered at top, inlike manner, with other great flat stones.