On DrauiiiKj. 
425 
experienced in preventing^ clear water that lies in the land from 
fdtering through cellar-walls, the embankment of reservoirs, &c. ; 
and yet many drainers have an opinion that water cannot filter 
through the earth to a drain if it lies two or three feet deep. I 
have always, in my experiments, found that clear water would 
pass through any porous medium ; but that water holding clay in 
suspension would choke the most j)orous mediums, as the follow- 
ing experiments will prove : — I dug in the winter season, on a 
gravel soil, two trenches six feet long each ; and, after smoothing 
the bottom and sides of the trenches, poured clear water into one, 
and water holding clay in suspension into the other. The trench 
into which the water holding clay in suspension was poured ceased 
almost to filter after the first day, but the clear water in the other 
trench alwavs disappeared in about an hour. I also took two flower- 
pots, and filled them with light earth to within one inch of the top ; 
one was filled with spring-water, the other with water holding clav 
in suspension. The spring-water always disappeared in about 
an hour; but in the first instance the water holding clay in sus- 
pension required six hours, and after repeating the same it soon 
almost ceased to filter. 1 then took a third flower-pot, and filled 
it in the same way as the others, except that I put in two small 
earth-worms; then filled it with water holding clay in suspension. 
The worms, if the pot was filled three or four times each day, 
Avere sure to let the water pass, although I was careful to stop, 
every time it Avas filled, the bores which they opened for it to 
descend. I have always found in these experiments, when in- 
filtration ceased, that if about one-eiglith of an inch of residuum or 
mud deposited by the turbid water was removed, infiltration was 
as rapid as ever. 
I have mentioned these experiments to direct the attention of 
parties who have to drain clay soils to the importance of studying 
the principles which should guide them in their operations, so 
that the present wasteful expenditure of capital, in many instances, 
may give way to a system which, although in labour more ex- 
pensive, will effect a great saving in material, and protect the 
occupier against the loss arising from shallow defective draining. 
6th. TJic ■practical mode of drainwg clay land. hjin(j icet from 
sarfacc-icater, in ichicli is considered the lading out of the r/round 
for the mains and small drains, Sfc. ; with the cost of draiiiiiKj with 
tiles, irood, peat, turf or icedye, and hlock-draininc/. 
In laying down what I have found to be the best mode of 
draining tenacious clay-land, the expense is greater than tenants 
of uncertain tenure would generally consider themselves justified 
in incurring, and therefore with many the ordinary modes will 
be practised ; but there cannot be a question that the drainage 
