Important treatises upon the subject o f Artesian
Wells have lately been published b y M. H6ricart
de Thury and M. Arago in France, and b y M . Von
and described in Phil. Trans. London. 1797. The water o f this
well was derived from sandy strata of the plastic clay formation,
but so much obstruction by sand attends the admission of water to
the pipes from this formation, that it is now generally found more
convenient to pass lower through these sandy strata, and obtain
water from the subjacent chalk. Examples of wells that rise to
the surface of the lowest tract of land on the W. of London may
be seen in the Artesian fountain in front of the Episcopal palace
at Fulham, and in the garden of the Horticultural Society.
Many such fountains have been made in the Town of Brentford,
from which the water rises to the height of a few feet above the
surface.
This height is found to diminish as the number of perpetually
flowing fountains increases; and a general application of them
would discharge the subjacent water so much more rapidly than
it arrives through the interstices of the chalk, that fountains of
this kind when numerous would cease to overflow, although the
water within them would rise and maintain its level nearly at the
surface of the land.
The Section, PI. 68 is intended to explain the cause of the rise
of water in Artesian Wells in the Basin of London, from permeable
strata in the Plastic-clay formation, and subjacent Chalk.
The water in all these strata is derived from the rain, which falls
on those portions of their surface that are not covered by the
London Clay, and is upheld by clay beds of the Gault, beneath
the Chalk and Fire-stone. Thus admitted and sustained, it
accumulates in the joints and crevices of these strata to the
line A. B. at which it overflows by springs, in valleys, such as
that represented in our section under C. Below this line, all
the permeable strata must be permanently filled with a subterranean
sheet of water, except where faults and other disturbing
causes afford local sources of relief. Where these reliefs do not
interfere, the horizontal line A, B, represents the level to which
water would rise by hydrostatic pressure, in any perforations
Bruckmann in Germany.* It appears that there
are extensive districts in various parts of Europe,
where, under certain conditions of geological
structure, and at certain levels, artificial fountains
will rise to the surface of strata which throw
out no natural springs,! and will afford abundant
supplies of water for agricultural and domestic
through the London Clay, either into sandy beds of the Plastic
Clay formation, or into the Chalk; such as those represented at
D. E. F. G. H. I. If the Perforation be made at G. or H. where
the surface of the country is below the line A. B. the water will
rise in a perpetually flowing Artesian fountain, as it does in the
valley of the Thames between Brentford and London.
* See Héricart de Thury’s Considérations sur la cause du
Jaillissement des Eaux des puits fores, 1829.
Notices scientifiques par M. Arago. Annuaire, pour l’An. 1835.
Von Bruckmann fiber Artesische Brunnen. Heilbronn am
Neckar, 1833.
t The Diagrams in PI. 69, Figs. 1 and 2. are constructed to
illustrate the Causes of the rise of water in natural, or artificial
springs, within basin-shaped strata that are intersected by the
sides of Valleys, or traversed by Faults.
Supposing a Basin (PI. 69 Fig. 1.) composed of permeable
strata, E. F. G. alternating with impermeable strata, H. I. K. L.
to have the margin of all these strata continuous in all directions
at one uniformly horizontal level A, B, the water which
falls in rain upon the extremities of the strata E, F, G, would accumulate
within them, and fill all their interstices with water up
to the line A, B ; and if a Pipe were passed down through the
upper, into either of the lower strata, at any point within the
circumference of this basin, the water would rise within it to the
horizontal line A, B, which represents the general level of the
margin of the Basin. A disposition so regular never exists in
nature, the extremities or outcrops of each stratum are usually
at different levels, (Fig. 1. a. c. e. g.) In such cases the line a. b.