THE TIMBERS OF OTAGO.

Evening Star, Issue 4269, 1 November 1876, Page 1

THE TIMBERS OF OTAGO.

A very valuable pvper on tfie above <WM read at the Otago Institute’# night by Mr Blair, C.E. Wo iunAariee the first portion of it:—

m,. J- RROPER TIBS O* UMBERS. into 18 fR IVIS T? n paper is sub-divided mto ; the headings—Structure,-' Growth, Climate, Situation, • Foil, Felling Season! on * n 8» Decay •andPresefvk-' SSS+i,'** structure of timber is ibmpaWd i^fhsk£° f k nck waU * the vertipal'jpiiita ZT^ T 5 e w g the annual nngaMmeduflary rays, and ihe horijjpntal ones by the interlacing of bundles ofwOody H** 5 thb latterthofcj only visible to thermcroscopist; The mcdullary rays are thift plafes of woody matter fro “^ e l Pitfi to the irk, and are what give called silver so mueh prized by cabSe£ SJf k P* tP the conversion-qf eap jnto neartwood under the heading Growtlu tO the eombmed action of the jmces tbeicomififeasive force exercised by Abe shrinkage ofthe ; outer rings aid bark, but againstthis idea ■ have the fact qftithS change being genei i e ur?? e: be perfect SLrt, quality. Whatever be the cauSb of‘ttiar ripening of the ' tunber, M: proSSS? i wjlfc' growt^fo^e^g^ |?* sapwood always decrease in Humbaraalliel :.W6e approaches .maturity, . •*. | .Chmat^Situation, and Soil,~The*piniow of ancient and modern authorities stl0 ? toHo whether slb?r growth in timber trees is essential'te nerfeo tion are compared, and Mr Blair inclmes to‘ theopmxpn thatrapidityof growth, is probably conducive to strength and ddfah&ty m the me tree when it is the result of good food and:vigorous health. The influence of situation and sod is shown by the following table, compiled'from the- 4 Forester*- *

fJjroaMi IWavotthie Oak 83 *nm n M Situation’, uar, Djye&n oIU ... Sliiadui ... 114 irmhoa . Boots pine, 50 do ... 17 do Larch, 35 do ... 17 a 0 "* .I* ??• ” Spruce fir, 35 do ... 15 do V.!" 142 FeUing,—The two most important considerations under this heading are -the age of the tree and the season of tha year. - Theproper age is at that stage when maturity has been reached and decline not begun, the zenith of growth, and ,ia growing itimber# this may be ascertained by observing whSt 7~e top snoots cease to grow, vigorously and the branches become stunted’ and authorities, considering■ the subject' apart irom its age, agree that the proper time for felling timber is when there is least sap in the tree,. yet a considerable variety of opinion ATinfj «ivfrr thft Bflason of thl--T*|i| in I which that time occurs.' On.the one band it is argued that there must be least sap during winter, as vegetation is then suspended: while the other side maintain that by midsummer the spring juices are expended 4 in forming leaves. Mr Blair gives it as his opinion that, as regards deciduous trees and trees m a cold climate, the chances are greatly in favor of winter felling; but with evergreens, and in a warm cfimate, there’ seems little choice between -summer frnd winter. It is admitted on all sides that" spring is the worst season for felling; and yet it is the one in which the English oak is cut, the reason of this being that , the rising sap enhances the value of the bark for tanning purposes. It is interesting, to learn that the ancients believed that the moon had , a ripening influence on timber, and that thisi belief still prevails in the forests of Ger-r many and Central America. In the latter it c has a commercial significance, as mahogany ’ guaranteed to have been out during the f proper phase of the moon commands'a comparatively high price. • -~ . Qualities,—The chief attributes of good timber are a minimum.amount of sapwood, compactness of texture, and depth bl color (where color exists). The ordinary defefita in growing timber, are the shakes or cracks and hollows that appear in the heart of full* grown and overripe trees. The “cup shake,” which;consists in a- want of coh£ sion between the .annual rings, is Otago, but the straight crack—tively harmless—and one of a stiff shape (which may seriously impair the strength of a beam) occur in several of our species, A" straight heart crack filled with gum or resin is very common in rimu, and the hollow heart is always met with m aged totara and cedar. Seasoning.—ln advocating-the great importance of this operation it is stated thjit - proper seasoning doubles the strength, of 1 timber and increases its durability to~an indefinite extent. Various methods of seasoning are then enumerated—.viz., barking a' few months before the tree is felled, naturally by the weather, and artificially by steeping in water, of by smoking, boding! steaming, or by drying in a heated atmosEhere. Natural seasoning is considered the est, the next best being to steep in running water. These methods, compared with the" others, ore slow, but what is gained in tuna by the latter is frequently lost in strength and durability. Tables are given to show the required for seasoning in several kinds of timber, also their relative weights in a green and dry state. Decay and Preservation.—This subject la dealt with at considerable length. The causes of decay are(lst) Chemical decay or natural decomposition by the'-action of the air and moisture; (2nd) cay or dry rot ; ahd (3fd) waste hy l destril'cl, tion by worms and insects. With referenda r to the first, the author ts not* aware of any cure; painting,, other m£apjs r J are employed, but they only retard the pro. gress of decay. The only safe course, says, is in the use of' durable timber, well la this connection, made of a plan to prevent decay in practice among our settlers—that Of when they , are put into the ground } and itis stated that while the benefit to be a£ riyed from this plan have generally been ro£' gjffded as experiments, wA* England have proved its efficacy, bak posts showing no symptoms of deoeyakc 16 years, ifhile those inserted in the usual way rotted in 12. Dry ret is a disease fit? duoed in unseasoned timber by defectun ; ventilation. It is little„khown in Otag& and for this exemption, we are indehta® simply to the defects in our wooden hnild* mgs, which give vhutilatimi. *~utijr met with oboasionally in* briak-vimd atone puildings in Dunedin, and is very obnuttofa

~Ea the timheiWlr 6 * third canse bf decay is aWo' of minor importance in Otago. The marine worms (which are described) have caused, some trouble, but the .land ones are scarcely known as destroyers in material that has been used. The effectual preservation of timber in all conditions is a problem not yet solved. Oleaginous and bitumirous substances retard the progress ef decomposition, but witho'ut thorough seasoning and ventilation they are of little value. Anything, that closes the pores of the timber while it contains sap, promotes decay. i * nomenclature. Under this head, it is stated that there is no subject connected with New Zealand timbers that is in such an unsatisfactory state as the nomenclature. The utmost con fusion exists in the names of many kinds, and there are very few that bear the same name throughout all parts of the Colony. In consequence of our ignorance on this point, many of the best timbers have been rejected, ■' and inferior ones accepted in their place —a proceeding which has xed to disappointment and loss both in private building and public works. With the view to remedy this evil, a table (prepared by Mr Blair) is appended to the paper, showing the various names of * all the principal Otago woods. This_ table gives the names of twenty-nine Otago"trees, classified as hardwoods and softwoods, and arranged under the headings—“ Popular Name,” “ Synonyms,” “ Authority,” “ ite marks. ” The billowing arc two examples in an untabulated.form;—Popular t ame—Karmai; Synonyms—AVeinmannia racemosa, tawhero, karmehi, towai, tawsi, black birch, red bircb j Authority—Hooker, Maoris ditto, ditto, ditto, ‘Settlers, ditto; Hem rks—B-tanic name according to Lyell, ditto to Hector, ditto to Col nso, ditto to Cunninghamso called at Catlio’a River, ditto in North I aland ano South Otago. Popular name—Red birch ; , Synonyms— Pagus fusca, butu tawhai, towai, fawai, < tawhai-rau-mti, black birch, red Varm^i; Authority—Hooker, Maoris, ditto, ditto, ditto, Settlers,, ditto; Remarks— Sotauicabname, according to Kirk, ditto to J&foiir, ditto to Bid well, ditto to Oolenso; bailed in the JN orthem Provinces and by -tWiGR*, fent not ii* Otago; so called i» 'South- Otago. - Ak the' leading Colonial authorities !k*ve been consulted in* the construction of the table* “ a y* the whole, . be considered accurate and complete. •, ■ GEOGRAPHICAL DISTRIBUTION. According to an official return, the forests of Otago occupy an area of 3,500 square miles, ' They are distributed chiefly along the seaboard ' —there being an almost continuous belt right ’'rpund the coast—and in the interior of Southland and the Lakes and West Coast . regions, and Stewart Island. It is estimated .roughly that in the interior of Southland and the Lakesdistrict there is an available supply of birch of about- 400,000 acres in extent/- Birch does not ‘ exist in forests, except on the West Coast, under an altitude of about 900 feet. At present our principle supply •{ Provincial timber comes .from Southland and Gatlin’s River, where ‘the forests are accessible by railway and water carriage.