October i, 1887.] THE TROPICAL AGRICULTURIST, 
231 
possibly contemporaneous with the cedars of Lebanon. 
The word " eucalyptus "—from eu, "well," and 
lcalypto, " to cover "—is aptly chosen to distinguish 
this splendid family of plants from all others. This 
characteristic is observable in the limb of the calyx, 
Completely covering the flower before expansion ; and 
during its gradual development, the operculum, or lid, 
in uplifted iu shape like an extinguisher, which falls 
nil immediately the llowcr becomes matured. The 
chief characters of all eucalypts are in the firmness 
of the calyx, the absence of petals, the numerous 
rows of stamens inserted close to the edge of the calyx 
tube, the stamens being nearly always fertile, and 
also the many form-variations of the anthers in the 
different species. It is upon these variations of form 
that the division of the geuus is arranged. This sys- 
tematic arrangement was made by the late vener- 
able lientham, and acquiesced in by our Government 
botanist, liarou von Mueller, as being the wisest to 
adopt. The eucalyptus is an evergreen ; it casts its 
hark annually, but this does not take place, like the 
falling leaf of England, at one given period of the 
year, hence there is always a rough and ragged appear- 
ance on the trunk of the tree. In the vegetable 
kingdom the Eucalypti belong to the myrtle family, 
so placed on account of its bearing certain botanical 
outliues to that of the garden myrtle of Eugland ; 
but tho physical characters, as well as some peculiar 
botanical features of the eucalypts, place them as a 
distinct genus iuthe myrtle family of plants. Consider- 
ing the vast area of the Australian continent — consist- 
ing of something over three millions of square miles, 
and measuring 2,500 miles from west to east, and 2,000 
miles from north to south — it is surprising to fiud oue 
tribe of trees forming at tho present day four-fifths 
of the whole of the indigenous vegetation. Au Aus- 
tralian traveller frequently feels the monotony of the 
scenery, but this is greatly dispelled by noticing the 
interesting variations in the leaf formation, iu the 
colour both of leaf and llowcr, iu the appearances of 
the tree-bark, and in shape and varied stature of the 
trees, Of the 150 kinds or species found existing over 
Australia, it can easily be understood that the vari- 
ations must be very great indeed. On the mountains 
and iu the valleys, aud ou the alluvial flats where 
tho woodman's axe is but seldom heard, stand gigantic 
eucalyptus timber free-., iu girth varying from 10 feet 
to 80 feet, and in height from 200 to 420 feet, and 
that often without a branch, the top being capped 
with radiating branches (like the ribs of an 
Umbrella) full of foliage. Iu the scant rain tracts of 
Australia there are many millions of acres on which 
grow a scrub of dwarf eucalypti, averaging in height 
not more than eight feet ; this scrub is so dense 
that it almost shuts out the sight of sun and sky. 
All hough the leading forest timbers of Australia cou- 
Sist of the eucalyptus,* yet there are a variety of 
other kinds. In the eucalyptus the wood varies in 
character quite as much as do other kinds obtainable 
from other timber trees; for instance, the well-known 
blue gum (/•.'. Globulus) is a hard light-coloured timber 
of great strength aud tenacity, as well as durability 
extensively used for beams aud joists iu buildings 
and lor railway sleepers, also piers aud bridges — 
for which purposes a test has been made between 
some blue gum, Knglish oak, and Indian teak. The 
* Most of the furniture in Australia is made of 
eucalypt timber, and it is found to bo admirably 
muted lor all kinds, from exquisite and artistic drawing- 
room furniture to ihr rough kinds used iu the kitchen. 
The lecturer exhibited specimens of the timber and 
pointed out its remarkable tltsusity. Tliu wood t tikes 
many years to mature, but when it does mature it is 
almost imperishable. A railway sleeper of /■.'. rox- 
trtlta wood was also shown which had been "22 years 
under the ground, yet it was almost unaffected l>y 
this long exposure. He bad soon piles taken up in 
Sydney which, after til! years, w, re ill such good 
condition (hat, niter u fine shaving was removed, it 
was found that the wood was as fresh us tho day it 
was put dowu. 
blue gum carried 14 lb. weight more than the oak) 
and 17 j; lb. more than the teak per square inch- 
The red gum tree (/?. rodratd) is a very hard compact 
wood, possessing a handsome curled but short grain, 
red in colour, well adapted for many purposes in 
ship-building, such as heavy framing, beams, and 
knees ; it is also used in the construction of culverts, 
bridges, aud wharfs, and by whecl-wrights for the 
felloes of heavy wheels, and is employed in Australia 
for railway sleepers and engine buffers ; and owing 
to an acid it contains, termed "Eucalyptic acid," it 
resists the attack of the Teredo nnvalis, or sea-worm. 
The ;iron bark gum-tree is oue of the hardest and 
heaviest of our native woods. The stringy bark tree 
(E. obliqiM) is an easy-splitting wood, and is usually 
employed for palings, shingles, and posts ; in like 
manner do all the varieties change. Many varieties 
of tree acacias are met with in all the forests of 
Australia, such as the myall aud the wattles, also 
pines, bauksias, casurinas, pittosporums, eugenias, 
melaleucas, and others too numerous to mention. 
There is a factor at work throughout Australia 
which makes the climate so acceptable to human life, 
and that is the eucalyptus vegetation, belonging, as I 
have before intimated, to the myrtle family of plants. 
It is full of aromatising odours; the sense of smell 
wheu in our forests, or even travelling in the country, 
bears ample testimony to the presence of its volatile 
bodies in the air, for there is no mistaking the odour, 
as it is different from all others. There is not a 
single species but what possesses in its leaves a volatile 
essence. Each kind varies in percentage of yield, but 
still of the vast number they can be reduced for pract- 
ical illustration under eight types, or species, namely: 
— The yimikalis, or manna-yielding eucalyptus; the 
adorata, or sweet smelling ; the rostrata, or red gum 
tree; the obliquu, or stringy bark; the ieucoxi/lo>t, or 
irou bark; the Globulus, or blue gum; the duttiosa, or 
malice; the dmygdalina, or peppermint-scented eucalypt- 
us. The eight kinds I have mentioned supply the 
minimum to the maximum, the minimum yielding 7 
fluid 07.. of the volatile essence, and the maximum 
500 fluid oz., or 25 imperial pints from every 1,000 lbs. 
weight of fresh leaves. No vegetation occupying 
so vast a country contains so much volatile bodies iu 
its leaf portion as the eucalyptus ; assessing alone the 
whole colony of Victoria (being that part of Australia 
in which most of my experiments were made, and I 
may tell you that I have practical experience extending 
over thirty years) at the low average of supply of 'IQ 
oz., or 1 pint to the acre, we have 9,730,500 gallons 
of au essential aud volatile substance held at one and 
the same time in the eucalyptus vegetation. So far 
as I have been able to proceed in this investigation 
over the continent of Australia, similar conditions exist ; 
so that it may be safely asserted that iu the whole 
of the lent' surface of the eucalypts iu Australia there 
is continually %, 877, 110,000 gallons of this volatile 
material. If, therefore, the whole of the odorous 
principles were retained in the leaves until set free 
by the art of man, iu that case its effect on climate 
would fail; but if they are given up freely by tho 
natural forces of the tree under the aid of light, heat, 
or electricity as existing around, or by some or all 
of these forces in combination, then we have good 
reasou to value tho eucalyptus vegetation beyoud all 
othtrs iu being capable of influencing the climate of 
a country for purposes of health. Leaves of trees 
necessarily are iu close connectiou with the roots ; 
together they keep up a coutiuuous action of ex- 
halation and replenishment; evergrecu trees, especially 
the eucalyptus, unlike deciduous trees, which sleep 
during many months of tho year, work constantly, but 
at times less energetically. Deciduous leaves generally 
perform their functions on one side only, that is, they 
change the sap juicos of the plant ou the side turned 
upward to the sun; but in the case of the eucalyptus 
it is quite different — these have a double action. 
There is no difference iu the anatomy of tho two 
sides of the leaf, breathing poros abound on each side, 
and the cells coutaiuiug the volatile oil ruu through 
the leaf. Those oil-cells iu most cases are visible to 
I the uaku I e ,o, aud cau bu couutod iu hundreds. 
