41 
not too full of roots, an able-bodied’ man may dig from eight to 
ten cubie yards per day. 
Surface Drainage is the more widely used system adopted by 
fruit-growers. Its chief objection is that it at times interferes with 
horse-cultivation. It is chiefly used for draining boggy land, and 
often prepares the way for deep drainage. 
For draining a slope or cutting off water rushing from a rising 
catchment area on to a low flat below, these drains should be made 
almost at right angles with the flow and empty into a main drain 
below. The cost of making them is small, and if scoured before 
the wet season sets in they often prove amply sufficient for draining 
a piece of ground. 
Sinkhole Drainage—Amongst the limestone coastal ridges, 
swamps are often met with which have a retentive marly bottom. 
Underlying that hard pan, sand and limestone are again found. 
That marl is rich, but as the surface soil above is shallow, and for 
the greater part of the year partly under water, the ground is unfit 
for fruit culture. In other places a rotten ironstone conglomerate 
sometimes called “‘coffee rock’? occurs below black mould. In such 
hollow localities, where water cannot be carried away by any of the 
other methods of drainage, holes sunk through the retentive hard 
pan often carry the water away into the porous soil below very 
economically. This is done with the pick or by blasting. 
Deep Drainage, if costly, is, for cultivated fields, the most 
suitable system of improving wet land. Teams and implements 
ean’ run without obstruction; weeds and rubbish are swept away, 
and have no chance of taking a hold of the land, and the greatest 
amount of benefit is derived from cultivated crops. It dispenses 
with open ditches and prevents surface wash, and consequently 
often great waste of fertility. The method consists in onening 
deep furrows or ditches, filling them partly with brushwood, logs, 
stones, or setting draining pipes in them and covering them up 
with the soil thrown out when excavating the ditch. 
The grass trees (Blackhoys, Kingya), which are plentiful in 
the moister region of Western Australia, where drainage is chiefly 
required, supply excellent material for drains A trench is dug to 
the required depth, sufficiently wide to allow two blackbov trunks 
being laid side by side, the scales facing the way the water runs. 
Over these a third blackboy stem is laid, the three forming a 
triangular prism. The trench is then filled with earth, which is 
trampled down to counteract subsidence. and a crown one or two 
inches high is raked together along the line of trench to throw off 
heavy storm-water, which might earrv away the freshly-dug earth 
in such places where a slone occurs. Blackhboys, and more especially 
grass trees, on account of the resinous matter which is contained 
