292 
THE MIDDLE LIAS OF NORTHAMPTONSHIRE. 
off the surface in open watercourses, and so assist in pro¬ 
ducing floods. It is asserted that such under-draining would 
tend to diminish floods by deferring the discharge of water 
from the land in the manner indicated. 
The heavy floods of the few years preceding 1884, in 
Northamptonshire, are attributed to want of drainage rather, 
for there was then more land wanted draining than there had 
been for twenty years previously, and this largely because the 
heavy rains had burst up the drains, and they wanted relay¬ 
ing. The depth to which rain must sink before the drains 
can act, the slowness of discharge from drain pipes compared 
with surface discharge, also the large amount of porous 
upland—estimated at not less than one-tliird for the district 
we are particularly concerned with—neither requiring nor 
having any artificial aids to discharge its water, are pointed 
to as evidence of the small effect land drainage can have had 
in increasing floods. 
The exact manner in which drains act gives rise to 
difference of opinion, this probably depending upon the 
character of the land with which each person is best 
acquainted. Where a comparatively porous bed rests on an 
impervious one at a small depth below, the drain pipes will 
receive most of their water upwards, after the lower portion 
is saturated ; in most other cases the saturation plane would 
travel downwards rather. 
As to whether drainage diminishes percolation sufficiently 
to seriously interfere with springs from underlying porous 
beds, it is pointed out that although districts with a deficiency 
of water are often those where drainage has been most 
extensive, still the very fact that such drainage is necessary 
shows that impervious beds constitute the subsoil, and so 
percolation would be small. 
I have already given reasons for the opinion that the 
marlstone water supply has not been seriously diminished by 
land drainage. 
That land drainage does help to cause floods is, however, a 
justifiable conclusion, I think, and the chief reasons for this 
opinion are detailed below :—On stiff, undrained, and badly 
cultivated land water will stand in the furrows, and every¬ 
where where a concavity exists, for days, and even weeks 
at some parts of the year, and only get away very slowly 
indeed by dribbling through weed choked ditches, by 
percolation into the ground when the water previously there 
permits it, or by evaporation. Compare this with the condition 
of well cultivated land, where the watercourses are kept free, 
and every facility given for the water to rapidly get away, and it 
