Oh the Drainage of Land. 
339 
no water runs off except by the drains. Rubble-draining is rather 
an ancient practice here for short lengths, and for tributaries to 
the wall-drains, but they are not generally laid out in the right 
direction, or put in deep enough ; the following used to be a 
common way of laying them out, and is still carried on to a con- 
siderable extent ; a drain is made up the piece, with arms branch- 
ing off on each side, thus : 
is not at all to 
be recommended, as part of the branches are put where the land 
would be dry without them, that is at the junction on each side of 
the upright drain, and the other part, from being across the fall, will 
not act to the greatest advantage : the same length of drain made 
parallel with each other will drain considerably more land. 1 
have cut across old ^wr/'-drains completely choked up with mould. 
They were rather shallow and I suppose had not been rammed, 
but made as before described, the turf being placed as a cover. 
I consider clay so much preferable to turf from there being no 
vegetable matter in it to decay. The present practice is not, as 
it ought to be, carried on upon the same system through the 
whole country, though the circumstances may be the same; a 
piece of wet clay-land in Cornwall ought to be drained upon the 
same principle as in Scotland and in all the country between : the 
distance of the drains indeed must vary according to the tenacity 
of the clay. I will recapitulate what ought, in my opinion, to 
be the present practice ; the depth should be at least 30 inches, 
especially in tenacious soils, filled in with the soil which has been 
taken out; the distance to be ruled by the tenacity of the soil; the 
materials to be stones, tiles, or clay, to be laid out in the direction 
of the greatest fall at equal distances, except where the land lies 
in ridges, when they should be put in the furrows ; but I would 
not ridge land up more than before draining, neither would I level 
that which has been before ploughed in ridges. 
Districts in England which require the most extensive efforts in 
Draining. — To answer this question properly requires to have 
travelled more than I have done ; still I have seen enough to 
satisfy any one (however much has been done) that there is a vast 
