Field Drainage. 47 



regular inclination, when there is a fall, should be given 

 throughout the whole length of the drain. In selecting pipes, 

 those should be chosen which are evenly burnt, and which 

 are not warped or twisted, and care be taken in laying them 

 in the ground that the ends properly fit 



Men by constant practice acquire a wonderful skill in 

 judging of the fall of the ground, and the regularity they 

 give to their trenches ; and where the ground is wet and the 

 water either runs away or follows them, they cannot get far 

 wrong ; but in dry ground, and especially where it is uneven, 

 the eye of the most practised drainer is apt to be deceived. 

 Too much attention cannot be bestowed to this part of the 

 work, and the pipes should never be laid in the trenches or 

 covered up until the work has been inspected by a trust- 

 worthy foreman. To lay out a large system of drainage, 

 the use of a spirit-level is absolutely necessary. For the 

 drainage of single fields, the ordinary " boning rods " com- 

 monly used by workmen in setting out short sections of 

 earthwork are sufficient These rods are made in the shape 

 of the letter T, about 3 feet 6 inches long, the cross being 

 14 inches, and the size of the wood 2^ inches by \ inch. 

 One of the rods has a leg with the feet and inches marked 

 on it, which leg is made to slide up and down by means of 

 two screws working in a slot, and can be fixed at whatever 

 depth the drain is to be cut. The rods should be painted 

 white, and to render them more visible the top of one should 

 have a black line about half an inch deep on its upper edge. 



The method of using is as follows : — A peg is driven in. 

 the ground at the upper end of the trench, and another at the 

 lower end. The level of these pegs being set by the spirit- 

 level, with reference to the outfall, the drainer causes one of 

 the rods to be placed on the upper peg and the other on the 

 lower, the rod, with the adjustable leg being set to the depth 

 the trench is intended to be, is moved along it so as to keep 

 the three in a true line. Any elevation or depression in the 



