107 
SEASONING. CAUSES OF DECAY. 
to economize yard spare and at the same time to put heavy pressure upon 
timbers that would otherwise be liable to warp and twist. Builders often dry their 
oai( s y p acmg t em obliquely and alternately on edge against a cross bar; but 
tins niethod takes up a great deal of space and is not so suitable for the timber 
>ard. W here the ground is exceptionally dry or where there is overhead cover, 
goo results may be obtained by placing the timbers on end in a nearly perpen¬ 
dicular position. 
viln drying hastens the seasoning process and gives more uniform results than 
any natural temperature method. The kiln usually consists of a specially built 
ong shed furnished with hot-water pipes for supplying heat and vapour and with 
rails for carrying trucks. The timber carefully stacked on the trucks with battens 
between the layers of planks, is passed in at one end of the shed and carried on in 
stages to the other end. It is then passed out to he further seasoned by the air at a 
natuial temperature, either in the yard or in another shed. Ivilns have been designed 
121 various ways; but they all provide for heat to evaporate water from the wood, 
'vapour to prevent too rapid drying of the wood at the surface, and circulation of 
the aii to ensure equal treatment for all the timber. Successful experiments have 
been made with electricity as a seasoning agent. A powerful current is passed 
through a stack of green timber so as to heat the moisture within the wood and 
diive it to the surface. R. T. Baker in The Hardwoods of Australia and Tlieir 
Economics describes all these and other methods of dealing with hardwood 
timbers and gives the names of Australian firms that are employing them. The 
reader is referred to that work for full information. 
PRESERVATIVE TREATMENT OF WOOD. 
Next in importance to the production of wood is its longer preservation in use. 
If we could double or treble the durability of all our wooden structures, our 
plantations and forests would correspondingly rise in value. Many experts believe 
that this can be done. The perishing of wood is due in part to purely chemical 
and physical reactions; but mainly and generally it is a complex process in which 
vegetable and animal organisms are concerned as destructive agents. 
The vegetable enemies of wood are either bacteria similar to those that 
produce ordinary fermentation or plants included in the great family of the fungi. 
They are all reproduced by spores, which are exceedingly minute, countlessly 
numerous, and endowed with very persistent vitality. Whenever and wherever 
conditions favour them, these bacterial and fungal organisms rapidly develop, 
penetrate the wood, appropriate its albumen as nutrition, and disintegrate its 
tissues. The animal enemies of wood are what we call borers. They destroy the 
wood by burrowing into it. There are two main and widely remote orders of 
them as follows:— (a) Terrestrial borers. These attack living or dead wood on 
land only. They are insects. Some of them burrow into the wood while they 
are in the larval or grub stage and pass the gnawed material through their bodies 
as food. Examples in New Zealand are Anobium domesticum, the furniture 
beetle; and Lyctus brunneus, the powder post beetle. In Europe Xestobium 
tessellatum, the death watch beetle, is the ally of Anobium domesticum. Other 
