28 
On Thorough- Drain'mg. 
inches deep. Thus we have by means of the ph)ugh a drain 10 
inches wide by 10 inches deep, as in the following figure, where E 
represents the slice turned out by the deep-breasted plough, and 
D the furrow formed by it. 
A labourer with a common spade now digs out a spit 9 inches 
deep, beginning at the eye, according to the following sectional view, 
where G represents the spit thrown out by the broad spade, and 
F the trench made. 
Then with a narrow spade the labourer takes out 1 1 inches 
more, and scoops out the crumbs : 
In the following sectional view J represents the spit thrown out 
by the narrow spade, and H the trench or drain left by it : 
