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Artesian wells, commonly bored for in tracts of country 
whose strata are characterized by a basin form, as in the 
tertiary neighbourhood of London, by perforations through 
the clay and plastic clay to the subjacent chalk, owe the origin 
of their flowing fountains to the hydrostatic force of water 
thus locked up by uninterrupted beds of impenetrable material, 
preventing further vertical and lateral descent. On Norland 
Moor two or three natural springs of this kind are to be 
seen after the rains, shooting up their flowing streams into 
the air. The theory of such discharges is simple, and explica- 
ble perhaps best by reference to a section. 
The loftier regions, attracting much of the moisture of the 
atmosphere, furnish lasting reservoirs of water, which descend 
m impetuous torrents, rivulets, or tranquil springs, and irri- 
gate the land below. Rivers often obtain their sources from 
these summit ridges, as the Calder, into which our whole 
system of drainage flows, from the heights of Todmorden. 
In common with most hilly districts, the parish of Halifax 
abounds with springs, some of which, from the medicinal 
nature of the substances held in solution, obtain the name of 
mineral or spa waters, whilst others, still containing more or 
less of foreign matter, (for there is not in nature a chemically 
pure water), are employed in domestic use. The saline ingre- 
dients of all these springs are to be ascribed to the neigh- 
bouring strata and alluvium, from which, at points of the 
easiest access, they topographically issue, and when they 
exude from a sandy gravel, or silicious matrix, as does the 
town water of this place, they are, properly speaking, pure, 
more agreeable to the palate, and have a greater specific gra- 
vity than other land waters. 
There are several springs in the parish which are called 
spas, and have probably been stronger formerly in saline im- 
pregnation than they are found to be at the present day. 
The Spa tvell, a quarter of a mile south of Elland is the best 
