M. Peligot has ascertained that the Water of the Artesian Well of
Grenelle contains not the least trace of air. Subterranean waters ought
therefore to be _aerated_ before being used as aliment. Accordingly, at
Grenelle, has been constructed a tower, from the top of which the water
descends in innumerable threads, so as to present as much surface as
possible to the air.
The boring of this Well by the Messrs. Mulot occupied seven years, one
month, twenty-six days, to the depth of 1794½ English feet, or 194½
feet below the depth at which M. Elie de Beaumont foretold that water
would be found. The sound, or borer, weighed 20,000 lb., and was treble
the height of that of the dome of the Hôpital des Invalides at Paris.
In May 1837, when the bore had reached 1246 feet 8 inches, the great
chisel and 262 feet of rods fell to the bottom; and although these
weighed five tons, M. Mulot tapped a screw on the head of the rods, and
thus, connecting another length to them, after fifteen months’ labour,
drew up the chisel. On another occasion, this chisel having been raised
with great force, sank at one stroke 85 feet 3 inches into the chalk!
The depth of the Grenelle Well is nearly four times the height of
Strasburg Cathedral; more than six times the height of the Hôpital
des Invalides at Paris; more than four times the height of St.
Peter’s at Rome; nearly four times and a half the height of St.
Paul’s, and nine times the height of the Monument, London. Lastly,
suppose all the above edifices to be piled one upon each other,
from the base-line of the Well of Grenelle, and they would but
reach within 11½ feet of its surface.
MM. Elie de Beaumont and Arago never for a moment doubted the final
success of the work; their confidence being based on analogy, and
on a complete acquaintance with the geological structure of the
Paris basin, which is identical with that of the London basin
beneath the London clay.
In the duchy of Luxembourg is a well the depth of which surpasses
all others of the kind. It is upwards of 1000 feet more than that
of Grenelle near Paris.