12 
Observations on Overflowing ' Wells 
v 0 [Jan. 
distance from a bored well affording water, may not yield any, should the latter, 
for example, be fed by a subterranean current, in place of being supplied by a 
sheet of water, or should the perforation be made upon the extremity of a basin 
with inclined strata resting upon a formation of a different nature. 
We shall not here enter upon any details respecting the art of boring Artesian 
wells, such not being our object. M. Gander's Manuel du fontenier-sondeur c on- 
tains all that can be desired on the subject. 
Taking a general view of what we have said, we deduce the following conse- 
quences, which we believe to have been sufficiently demonstrated. 
There exist great subterranean sheets of water at various depths. These sheets 
are more commonly met with in the plane of superposition of strata of different 
formations They, however, frequently occur at various heights in the great 
masses such as those of clay, chalk, and even marine limestone containing cerithia, 
when these masses are entire, and of great thickness. 
According to the slope, the undulations, or the declivity which are presented by 
the plane of superposition of the permeable deposits in which the waters flow 
™ per z e those ?reat shce,s ° f *■«“■ « ■»* wm, at an depth, ; 
but it is impossible to lay down any constant rule with respect to them 
In order that these waters be capable of ascending, it is necessary that the for- 
matrons among which they occur be entire, in the state in which they were ori- 
g na y deposited, and that they be not intersected by large vallies, or deep ravines 
in which the waters would find a free and easy exit. P ’ 
It would be in vain to search for springs in deposites which, at no great distance 
rom the place of boring, are intersected by vallies, or when the form f„ 
Bongial, &C. ° chalk at Me “<Ion, Sevres, Auteuil, 
In these different localities, we nepd nr>t o,- 
uniess by penetrating deeply into the mass of tWh^k^ f ° r SpringS ’ 
water in its lower part, or even bv ,• a ln searcb °f the sheets of 
those in the clays, oolites, and shell-IimeltolT " ' n ° rder to come 
deeply into the latter, when they happen to he • °', y ’ Unless b > _ Penetrating 
cliffs, or are intersected by valleys of greater or ^ Surfacc ’ arld present 
on this subject it is necessary “ lst • 
elevated plains, such as those of Champagne N ‘ a countr y composed of 
»ny other of the same nature, or of simiPw fn 1>icSrdy and Beaure - nr 
necessary depths for reaching the different wat '“ “'h m P Iace n( boring to the 
-ost abundant, and, at the same time ‘C T *** are “"-only the 
stopped at higher levels less distant from the “u ' " the b -Lg is 
the d C ^ Se ’ the ascendin S waters would ston ^ ** 1S m ° re than P roba ble that, 
,he depth oftteb »i ore or “ the “ ° r 
ing to^theY T 6r n0t failed > Realise in 
cleficiencr ^ ^ ^ ZZty 
tnus, for example, w l. P n 
number of yards from the suri ceTtut f within a certain 
“ SU ® C,ent H might be conducted 
