594: QUEENSLAND AGRICULTURAL JOURNAL. [1 Dec., 1899. 
Flowers.—The flowers are in pretty white small axillary cymes, on a 
common peduncle or flowerstalk, and appear in bloom from November to 
January, and are sweetly scented. They are much sought after by bees. 
Fruit.—The fruit isa small capsule about one-sixth inch in diameter, which 
seeds in May and June. 
Vernacunar anp Borantcat Nawes.—The Swamp Mahogany, so called 
first from its growing in swampy localities, and secondly from the resemblance 
of its timber to mahogany, is also known as the Broad-leaved Water Gum 
(from the shape of the leaves and the locality of its growth), the Sweet-scented 
Gum (from the smell of its flowers), and also the Bastard Mahogany and the 
Bastard Peppermint. The generic name Trisfania was given to this genus 
by Dr. Robert Brown (one of the greatest botanists of the age, and the one who 
laid the foundation of a thoroughscientific knowledgeof Australian botany), from 
the disposition of the flowers and leaves, and the specific names of this species — 
suaveolens—was given to this tree by Sir J. E. Smith (the gentleman who 
purchased the herbarium of the great Swedish Naturalist, Linnus, and who 
was the founder of the Linnean Society, the greatest society devoted to botany 
in the world) from the sweet scent of its flowers. 
Disprreurioy.—Che Swamp Mahogany is found along the banks of fresh- 
water streanis, and often on the borders of and even in marshes and swamps in 
the coastal districts of Queensland, and also in the northern portion of New 
South Wales and North Australia. 
Usv.—The Swamp Mahogany yields a strong, durable, elastic, tough, 
reddish-coloured timber, resembling very much that of the Spanish Mahogany, 
Tt is hard and close grained, and is a remarkably fine material for various kinds 
of work, either underground or under water, have been found to be extremely 
durable. It is extensively used for piles for wharves and jetties, as it is found 
to resist the ravages of the teredo, or cobra, much longer than many other timbers 
which have been tried up to the present. [+ is also a good timber for piles for 
bridges, and for boatbuilding. It is also useful for carpenters’ mallets and the 
cogs of wheels in machinery. When dried properly it works easily, but it warps 
very much in drying. It is used by the aborigines for making boomerangs. 
The flowers of this tree are amongst the most valuable honey producers. 
They produce, perhaps, the finest in this colony, the honey being of a delicate 
colour and of a delicious peachy aroma and flavour. 
There is a variety of this tree—Tristania suaveolens, var. glabrescens, 
which differs from the normal form in having its foliage destitute of hoariness, 
and in having bright glossy or shiny-green leaves. It is found in low, almost 
swampy, localities in South Queensland. ; 
THE CHEMISTRY OF MATERIALS OF ENGINEERING. 
By Professor A. H. SEX'TON, F.1.C., F.C.S., &c. 
MATERIALS OF CONSTRUCTION. 
z WOOD. 
Woov.—Wood is very largely used for structural purposes, both temporary and 
permanent, its strength, its elasticity, and, above all, the ease with which it 
can_be worked, rendering it specially valuable. . 5 
Structure of a Tree.—W ood is the more or less hardened tissue of certain 
perennial plants—the timber trees—and as the chemical and physical characters 
of the wood are largely determined by the way in which it is produced, it is 
necessary to describe very briefly the structure and growth of the plant. All 
timber trees belong to the botanical class of the exogens or dicotyledons ; the 
endogens or monocotyledons, such as the tree-ferns, having a very different 
structure, and being quite useless for timber, 
