AUSTRALIAN HARDWOODS

Dominion, Volume 11, Issue 120, 7 February 1918, Page 8

AUSTRALIAN HARDWOODS

CHEAP, DURABLE, FIFE-I.'KiISTING. (By V. K. Trapp, 'n tho Melbourne "Argus.") Though there has been much groundless prejudice against tliem in the past, there arc signs that Australian hardwoods are about to eomo into their own at last. They have received their cachet, indeed, from the Koyal Victorian Institute of Architects, who have drawn up a schedule wherein these timbeis, graded, branded, and properly selected, may bo used in buildings so as to give ns good, if nut better, results than timIxr imported from the United Statw

and elsewhere. In Iho past the public have been deploijably ignorant as to the merits of the home-grown timber; and though to-day the prejudice is dying out, it has not altogether disappeared. But without doubt what the institute lias done will bear good fruit in educating

Australians to put a proper value on Australian woods. For, properly graded and selected, no other timber can be used for a greater variety of purposes. But this need of correct selection i« not yet ja matter of common knowledge.

Thus too often timber st.itab.le for bridge-building is specified for joinery, and that which would be perfectly adapted for joinery is incorporated in bridges. Tt is an instance of the round peg in (ho square hole, and vice versa. To illustrate this by a ''oncretc example, timber from Southern Tasmania, very well suited for structural work, such as bridge-building, is specified sometimes for joinery, whereas in the north timber that would be admirable for furniture often finds its way into bridges.

It may be of interest to compare tne strength of our hardwoods with that of Oregon. Let us take an Oregon beam •with a section of sin. by .tin., and 20ft. long. Under a load of 19101b. it will break. Now, compare, this with a hardwood beam of similar .span, but having a, section of 3in. by 2in. only. Here tho material is 33 per cent. less. If it will not bear so sreat a load as will the Oregon beam this will be only about fl per cent. less. A saving of 33 per cent, of material for a loss of under G nor cent, in strength is obviously worth while. And now as to price. Oregon is sold at 40s. per 100 super, feet, hardwood up to 20ft. lengths, is 18;. Od. per 100 super, feet. So far as strength is concerned, as much can Ik obtained from 14s. invested in hardwood .isfrom 40s. invested in Oregon. This reminds me of another mistak" frequently made in specifications. For certain work it may be that Din. by 3in. Oregon has been used. Well, in nlnce of Oregon it has been thought desirable ft; use hardwood. But tho superior., strength of hardwood, is overlooked, and a similar section is ordered. As a matter of fact, Slin. bySin, hardwood is stronger than 9in. by 3in. Oregon. Here is yet another instance of a similar lack of discrimination. In the past -jin. and l;in. Baltic hitve always been used for flooring, and for special work ljin. kauri. Because of this the public seem to bo under fae impression that no other thicknesses should be used, and when specifying hardwoods they want tho same thicknesses ns the imported timbers. How erroneous this is will be understood if the tensile strengths of the two classes of timbers are considered.

Tensile strength, it may be explained, is determined by the weight that a piece of timber will carry suspended withuut breaking. In the statement appended the thicknesses vary, but the width of the plank is in every w*e 6in, The tensile strengths are as follow:— Jin. hardwood has a breaking strain of 16301b.; do. Tasmanian myrtle, 12351b. ; do. kauri (N.Z.). 8211b.; do. limn, 8101b.; do. white Baltic, 73(iib.; $in. hardwood has a breaking strain ot 22071b.; do. Tasmanian myrtle. 16811b.; do. kauri (N.Z), 11211b.; do. rimu, , 11021b.: do. white Baltic, 10001b.; IJin. hardwood has a breaking strain of 37481b.; do. Tasmanian myrtle, 27701b.: do. kauri (N. 8.), 18541b.: do. rimu, 18221b.; do. white Baltic. 16641b. From this it will be seen that hardwood {in. thick is almost as strong as many other timbers of ljin. thick. In a word, our }in. timbers ought to bo used in preference to all Jin. foreign timber. An advantage of both-hardwood and myrtle over foreign timbers is their lasting properties, for, being free from knots, they do not wear so irregularly. Tn prove this look at. a Bailie flouring and one of hardwood after both have been laid down for soma time. Fails and sleepers made from myrtle hove been in use for over twelve years without showing anv.signs of decay. None of the foreign timbers would last a quarter of that time.

■Roth hardwood and myrtle are termed "fire-resisting." nnd rightly; imported timbers are jup-h. tlio reverse. Of late there have been a number of instances in which kftrdwood tins either prevented or /retarded a fire. Tt is to be regretted that in our larje cities it ban not been insisted upon in the bni'ding rop-uln-tions that haTdwoods must be nscd in preference to softwoods. r>n account of Hie.-?! 1 fire-resistin? nrnnerties. Burning tests bnvc he<"i made in America and in Australia. The results arc. practieallv the samo. They pjiow that onr hn.«l-----n-nnd" l«ke 335 wr cent, longer to ignite (liau (Venn. 2W r>°r cent, longer than white ■Raltic, and Siti ne' cent, longer than New Znalnrol rinm. i r — m