ADDITIONAL NOTES ON TREE-TRUNK WATER-PIPES. 235
filthy or noxious, and generally it becomes transparent in a short time, if kept
still to allow the subsidence of the particles which occasion its opaque
appearance," &c.
As regards wells as a source of supply, our author mentions
them as giving but a limited and variable quantity of water,
which, if more "transparent" than river water, was frequently
much less wholesome. Thus, "the recent analysis of the trans-
parent water from the Treasury pump at Whitehall shows it to
contain extraneous matter to the amount of four times the
quantity from the Thames at Hammersmith, and the filtered
water from the Chelsea Works."
It is evident that the knowledge of the geological structure of
London and the district around it available in 1835 was utterly
insufficient to allow of the sinking of artesian wells there on
scientific grounds. Indeed, the earliest work of authority giving
the geological structure of the London district, with especial
reference to artesian wells, is Prestwich's Geological Inquiry
respecting the Water-bearing Strata of the country around London,
with reference especially to the Water-supply of the Metropolis ;
published in 1851. In this work we find only one allusion to
Hydraulia, and that is in a note on p. 9. Prestwich is there
noting the names of books giving details of the construction of
artesian wells. He mentions but one British work on that
subject, adding that Matthews' Hydraulia does not treat of this
question. But in this case the mere allusion to a book published
16 years before is evidence that Hydraulia was a standard work
on the subject of water supply.
My object in quoting so much from Hydraulia on the
turbidity and transparency of water is to bring into prominence-
one of the influences greatly retarding the adoption of waterworks
in the first half of the last century, but hardly likely to suggest
itself to us now. It is no exaggeration to say that the views on
turbidity suggest rather those natural to the cook at a hotel or
club, who found a feeling prevailing there that all soup but
"clear" soup was disgusting and dangerous to health, than such
as might be expected on clear water from an eminent advocate
of waterworks. In short, we must bear in mind that shallow-
well or pump water had the attraction of being usually clear, and
that turbidity and most imperfect filtration, if any, was to be
expected in 1834 from a waterworks' supply. Also that water
from artesian wells was almost unknown for some years later.