The Sun.
London, England, 1850-11-12 00:00:00

THE WATER SUPPLY OF LONDON.

The following interesting report has been pre-
sented to the General Board of Health, Gwydyr-
house, Whitehall, by the Hon. William Napier :
Part No. 1.

"Farnham, Surrey, Oct. 2, 1850.
"My Lords and Gentlemen,—Having had the plea-
sure of receiving in August last your instructions to visit
the gathering-grounds of the proposed water supply to
the metropolis, in order to gauge the streams and make
a careful re-examination of the general capabilities of
the country for the purpose intended, I have now the
honour to submit to your notice the results of my ob-
servations, with a few remarks on the different bearings
of the scheme.

"Oa rending the board's report presented to the
Houses of Parliament during the past session, I per-
ceived that from the very short time at the disposal of the
board the calculation of the quantity of water available
from the rain-fall on the district, an extent of nearly 150
square miles, was necessarily founded on the discharge
of the streams at their outfall.

" The board were thus also manifestly placed under
great disadvantage when endeavouring to asePrtain the
character of those waters; for, as such waters inevitably
partake of the nature of the soils through which they
have passed, and as the pure sands of the district are
not only !minded by clay on the north-east, east, and
south-east, by chalk on the west, but are also inter-
sected from east to west in the south by a high range of
chalk hills, the course and outfall of these streams pre-
sent certainly a widely misleading test of the quality of
the water to be derived from pure sands.
" Considering the purity and softness of the supply to
have the first claim upon my attention, I remembered
the principle enunciated by the board, the nearer the
source the better the quality,' and made it my first cb

jeet to examine the nature of the soils in which the
ainfall of the country makes its appearance after perco-
lating through the upper crust, nod next, the soils
throng!' which it pas,es to its outfsll.
" The water-supply of Farnham being derived from
the hid on the south side of which the village stands, I
bent my first steps thither, not only to examine its
source, as likely to present indications for purity
.to be
locked for elsewhere, but also to have a good bira's•eye
view of the whole area under investigation. Tho posi-
tion of the hill in the south-west, its elevation of nearly
700 feet above the level of the sea, and 300 feet above
the plains beneath, admirably adapted it to this pur-
pose. It was then only I discovered that the Farnham
water does not come from surface drainage, hut is de-
rived from sixteen small springs, issuing at the south
side, on a contour, so to say, about fifty feet below the
highest level of the hill, From the contracted area out
of which so large a supply is gained, I was induced
to suspect that these springs are not due to the rain-
fall on the ground above them. I was further led to
this consideration by observing that, from the slope
of the ground, and from the almost impenetrable
hardness of the superficial covering of the gravel,
the rain-fall could scarcely find its way through this
surface. • A violent storm having most opportunely
come on whilst speculating over this probability, I per-
ceived that the whole of the water apparently ran
rapidly down the hill-sides and was speedily out of sight,
leaving the surface perfectly dry, except where irregu-
larities retained a few pools, which subsrqusnt observa-
tion proved to me were exhausted by evaporation rather
than by percolation. I then examined the north side,
and found that on the same contour a still greater in-
dication of springs existed. This satisfied me that
these waters are due chiefly to rainfall elsewhere; for
a rough calculation of the yield of the springs much
exceeded the available rain-fall on the area within the
contour.

" Convinced of this, I naturally concluded that, if the
other ranges of the district were of like geological for-
mation, they would in all probability present similar ap-
pearances about the same level; a most desirable sourco
for the streams of the country, the advantage of which,
in addition to the proposed drainage supply, could hardly
be over estimated. The first week of my researches
was confined, therefore, to the nature of the soil through-
out the district, presenting generally a vast depth of
pure sands, obscured in the higher levels by extensive
patches of gravel from 2 to 20 feet in depth; in the
lower, by a poor loam, from one to three feet deep.
Patches of peat here and there in spots of some depth
exist principally in the lower levels. On the west and
south-west, the loam has a subsoil of very stiff clay, ap-
parently of the London formation, which also crops out
on the north side of Farnham hill. On the north and
hiehanveextproebp
object
td
oafs amcycurreastee
north-west, in the valleys, there exists within a small
bogs. All these are marked upon the
area a considerable quantity of iron in some of the peaty
plan which I:shall
hereafter have the honour to lay before the board, and
the quality
the time allowed.
was
se shortness of
whichT
their report,
and quantity of the water. The board, in
have given the quantity now brought into London by the
different water companies as a stream of 9 feet wide and
3 feet deep, flowing with a velocity of two miles an hour;
a supply double the actual consumption. In the course
of my exploration, I could not fail to observe that such a
volume of water of any quality P 739 no where to be
my hopes for the
seen, which at first rather damped
alyrchas
b, d ' h
future; but Irememberod that such
a)
y mtg
rivulets,
be
made up by collecting the smallest threads.of
then, was my
and went on my way. To effect this,

- .
object.
A most minute inspection of the gathering grounds
has shown me that their naturae
naturalexactly fialtdear,ptdsetplrieivnei
for the means of collection proposed by the board,•
namely, a system of thorough drainage. A more admi_
erhabhleeeivpeladn;
tohfe
sgaant
dh
se,riaccgtinragina-sfall could not have been
the water on its passage to the pipes of any impurity
contracted either in the air or in percolating through
the upper crust; as, for instance, where the water might
be discoloured by peat, experiments have proved that the
sands restore its primitive colour, and deprive it also of
the flavour imparted by the peat. The heath, which
covers the entire area of the gatherieg grounds, also
stains the water, but the impurity is removed by this
process of natural filtration. I would remark that the
discolouration visible in the stream called the Blackwater
is not caused by peat, but by the heath and loose black
o
loamy nature of the soil through which it flows. This
I have proved by following up its various sources, one
of which only, at C
Samples of
springs rising in pnve, passes over peat.
ty bogs show ho discolouration
whatever, but are as clew as water issuing from the

attention
Farnham
-ehill,
ulchtaunr.nde.cdlomsey examins-
stealing down the sands. .
to 1
forollecm e msbporriirnj
springs,
,F :renal;
hill-
sidessilver underth
tion, came to the conclusion that the origin of many little
grass, arose also from such sources. A
diligent search showed me thir, the quantity of writer to
be derived in this manner within the original area of
the gathering-grounds Is so great,. that if the neighbour.
eatdisloof water, bilvntly
ing ranges of mountains and hills on the south side—
namely, Ilindhetid, Blackdowcn, Hascombe-hills; Leith-
hill, &c., presented the same ,cadre, I might probably
hope to collect a stream nine feet wide and three fcei
deep, of the desired softness and purity.
" I am now happy to inform the board that a month's
researches into every hill and glen, every copse and
crevice, has produced this result. Having tasted the
waters as they issue from their sources. I can announce
that I have gauged a sufficient number of springs and
rivulets to enable me to form an . opinion both as to
quantity and quality.; the water be.n.g of its primitive
purity, perfect as to aeration, brilliant in colour, soft
almost as distilled water, of a grateful temperature, about