On Draining. 
261 
ditches into which the pipes, always running full bore, discharged 
their water, require clearing once or twice a year to keep them 
open. I also felt additional confidence in the sufficiency of small 
pipes, as I proposed laying them with collars, which would fur- 
ther help to cover and diminish the size of the crevice between 
each pair of pipes, and close it against the entrance of solid mat- 
ter. However, I devoted an entire week to the examination of 
old drains, many of which were quite stopped up with earth and 
iron deposit mixed ; of these some were composed of the common 
horse-shoe tiles laid without soles, and others with soles. The 
drains through which water was continually running were chiefly 
open, having great quantities of the deposit at their mouths, and 
one drain, formed of 6-inch pipes, conveying much water, exhi- 
bited the iron copiously as a precipitate when the line was broken 
and a pipe removed, which exposed the water to the atmosphere ; 
cesspools communicating with the atmosphere at top, and into 
which some drains entered, were also lined with deposit. I exa- 
mined several drains serving as mains, and particularly at their 
point of junction with minor drains, and I found one of these 
drains about 6 feet in depth, and very well constructed, to be 
nearly closed with what appeared to be a pure specimen of the 
deposit, having the red colour of peroxide of iron, and of a pasty 
texture. This particular mass of deposit had occurred at the 
junction of a branch with the main^ about 30 or 40 yards from 
the higher end or origin of each drain, and where the run of 
water would necessarily be greatly less than as it approached the 
outfall ; and I have found at Drayton Manor, and many other 
places where ferruginous matter abounds, that stoppage from its 
deposit is much more frequent towards ihe higher than nearer 
the outfall end of a line of drain ; and for the very obvious rea- 
son, that the flow of water there is greatly less both in quantity 
and velocity — and consequently of less force than it is as it ap- 
proaches the end of its course. This specimen was analysed by 
Mr. Richard Phillips, of the Geological Museum, Craig's Court, 
London. Mr. Phillips at once told me it was peroxide of iron, 
but I wished it to be analysed that I might know whether, and to 
what extent, the iron was pure or incorporated with other matter. 
The following is Mr. Phillips's report of its nature and of the 
manner of its production: — 
"Museum of Gcolofjy, ]3th Dec. 1845. 
" I have submitted the deposit occurring in the draining-pipes 
to analysis, and I find it to consist of, after drying — 
Silica and alumina, with a trace of lime . 49 2 
Peroxide of iron ..... 27'8 
Organic matter ..... 23 0 
100-0 
