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Replies to Minor Queries.
_Artesian Wells_ (Vol. ix., p.222.).--Wells are often so called without
just pretence to a similarity with those in Artois, whence this name is
derived. There are some natural springs in the northern slope of the chalk
in Lincolnshire, near the Humber, called _blow-wells_, which may be
considered naturally Artesian. The particular character by which an
Artesian well may be known is, that the water, if admitted into a tube,
will rise above the level of the ground in its immediate vicinity up to the
level of its sources in the basin of the district; this basin being usually
gravel, lying betwixt two strata impervious to water, formed the
surrounding hills, and extending often over many miles of the earth's
surface. If we conceive the figure of a large bowl, inclosing a somewhat
smaller one, the interstice being filled with gravel, and the rain falling
on the earth being collected within such interstice, then this interstice
being tapped by boring a well, the water will rise up from the well to the
same height as it stands in the interstice, or rim of the natural basin.
Such is an Artesian well. Supposing this huge mineral double bowl to be
broken by a geological _fault_, the same hydrostatic principle will act
similarly.
The question of _preferable_ put by STYLITES must be governed by the _cui
bono_. Universal adoption is forbidden, first, by the absence of a gravelly
stratum betwixt two strata impervious to water; and secondly, by the
excessive expense of boring to such great depths. Where expense is not in
excess of the object to be attained, and where the district is geologically
favourable, the Artesian wells are preferable to common ones derived from
natural tanks or water caverns, first, for the superabundant supply;
secondly, for the height to which the water naturally rises above the
ground; and thirdly, because boring Artesian wells, properly so called,
does not rob a neighbour's well for your own benefit, afterwards to be lost
when any neighbour chooses to dig a little deeper than you. This is a
matter with which London brewers are familiar.