[1 May, 1898. QUEENSLAND AGRICULTURAL JOURNAL. 411 
and for fencing-posts, &c. It is much esteemed by coachbuilders and wheel- 
wrights, as it furnishes good timber for poles and shafts of carriages and spokes 
of wheels. Railway sleepers of this timber have been known to last as long 
as twenty years. It is one of the most picturesque of the different species of 
Eucalypti called Ironbarks, and is worthy of a place as an ornamental tree. It 
is not, however, a very fast grower. 
TREES: THEIR BENEFITS TO MAN. 
By R. R. HARDING, 
Curator, Botanic Gardens, Toowoomba. 
TuereE is, perhaps, nothing which gives so much pleasure to visitors as the 
shade trees growing in the streets of any of the towns in the colonies. The 
shade received from them makes the walks cool, and the bright glare of the 
' gun, which is so trying to the eyes, is mellowed down to such a degree that 
walking in the streets in the noonday becomes bearable, and even pleasant 
to all. These must purify and regulate the condition of the air, and there 
is no excuse for not planting trees about our dwellings, because the 
means are within the reach of nearly everyone. What a comparison between 
two dwellings: one with the front and back exposed to the midday sun and 
the westerly winds, and the other well planted with trees and shrubs where 
the occupier can at all times enjoy the benefit of their shade! Which is most 
sought after, if to let? One hardly ever sees such a dwelling unoccupied ; 
the trees lend distinction to the meanest building, and enhance the value and 
grandeur of even the noblest. : 
A tree is indisputably the most highly developed form which vegetable 
life assumes. When one looks at its massive stem and branches raised from a 
little seed by means of which it has been drawn from the earth and atmosphere, 
one scarcely realises that this is merely the operation of the attractive forces, and 
that this mass of vegetable matter is only earth and air that have undergone 
transmutation. The leaves of trees, by a natural process of their own, absorb 
carbonic gas, which would be destructive to life if inhaled ; and these in return 
give out oxygen gas, the life and sustaining element of respirable air. ‘The 
oxygen of the whole atmosphere would, in the course of time, be consumed by 
the breathing of animals were it not for the singular provision which enables the 
leaves of the trees to supply oxygen and to keep up the due proportion which is 
necessary for the support of animal life ; and the gases which the trees absorb 
from the atmosphere are usually considered plant food, and also contribute to 
their growth. ; 
They also purify the atmosphere, counteracting the effects of animal life 
and various processes of decomposition; they also by their transpiration impart 
a degree of humidity to the air which surrounds them. They protect the 
ground from the direct rays of the sun, evaporate fluids elaborated by them- 
selves, and cool the airin contact with them by the radiating of heat from their 
leaves. ‘The leaves of deciduous trees are of such a nature that they perform 
more quickly than the same organs of evergreens the function of scavengers, 
and take into their system for purification the obnoxious gases hovering about 
our dwellings. Another important feature is that, owing to the deciduous trees 
casting their leaves every year, the new ones come fresh and full of vigour each 
spring, thus adding a degree of pleasure to the scene which is not always secured 
from trees of an evergreen character. 
Take the Eucalyptus globulus, which appears to possess an extraordinary 
power of destroying miasmatic influence in fever-stricken districts. It has the 
singular property of absorbing ten times its weight in water from the soil, 
which is returned to the air in the shape of vapours rich in camphor. ‘This is - 
gl 
