1822.] 
(see our 11th volume, p. 525, our 40th 
volume, p. 379, &o.) are now s0 far 
matured and known to many practical 
engineers, as to leave nothing want- 
ing in regard to the principles, by 
which the local extents of the districts 
capable of this improvement, in the 
place of wells and pumps, may be 
previously determined. And, fortu- 
nately, the great variety and extent 
of our mining and well-sinking opera- 
tions have reared a class of practical 
men, fully equal to the executing of the 
necessary works, without its being ne- 
cessary for the public to listen to the 
pretensions of affected new discove- 
ries, or to tolerate mystery on the 
subject. 
To such men it must be left to de- 
termine, by examinations of the neigh- 
bouring strata, how far the operation 
will be successful. It can hardly be 
expected that the water will ever rise 
higher than its subterraneous reser- 
voir, unless by lateral pressure, on the 
principle developed by Bolton in his 
water-raising apparatus. But these 
considerations are complicated; and, 
before any gentleman, company, or pa- 
rish begins the operation, it may be pro- 
per to obtain the opinion of practical 
men, just as in the case of mining, or 
other similar operations. Nor can the 
expense be reduced to a certain scale ; 
for it will depend on the nature of the 
strata to be passed through, and, in 
some cases,the besttools repeatedly fail. 
An expensive experiment has been 
recently made, without due regard to 
circumstances, by Mr. Laycock, of Is- 
lington, and has hitherto been without 
success. Mr. L. with much public 
spirit, has persevered ; and we delayed 
the publication of the present article, 
till we could announce the result ‘of 
his operations. The curiosity of the 
public having, however, been excited 
by our former articles, and many of 
our readers being impatient for details, 
we have judged it better to present 
them with these observations, than 
longer to defer them. 
[Since the previous article was written, 
we have been favoured with the follow- 
ing letter from an eminent practical 
engineer, and we hasten to lay it be- 
Sore our readers, as tending to com- 
plete their information on the subject.] 
To the Editor of the Monthly Magazine, 
SIR, 
Observing that the letter of your 
Tottenbam correspondent, 8. S. in p. 
290 of your last volume, which strongly 
Mr. Farey on Overflowing Wells and Bore-holes. 
35 
recommends the extension generally 
of-borings for water, in preference to 
the sinking of wells, has remained un- 
noticed by your many able correspon- 
dents; and having observed that the 
principle on which the “ genuine 
spring,” as 8.8. calls it, which has 
lain concealed under the village of 
Tottenham and its vicinity, is capable 
of rising, through a well or bore-hole, 
and overflowing on the surface, is not 
adverted to, and apparently is not 
known to that writer ; and conceiving 
that a right understanding of the prin- 
ciple alluded to, is of the utmost im- 
portance, towards preventing many 
persons from incurring the expenses 
of borings, in other and higher situa- 
tions, and afterwards experiencing the 
mortification of finding, that the water 
will not there rise to the surface 
through a bore-hole ; although, on the 
same spot, it might rise and stand per- 
manently, at a useful height, in a well. 
—I am on these accounts desirous of 
showing, in your instructive pages, 
that there is, in the principle I have 
alluded to, nothing of mystery or dif- 
ficulty : itis simply this, that the water 
contained in the legs of a crooked 
pipe, in the form of a U or a Y, or of 
an inverted syphon, will rise or flow to 
the same height (with respect to the 
horizontal plane) in each of its legs. 
Now the open and connected joints 
or cracks (that may be witnessed in 
any chalk-pit,) of the vast stratum of 
chalk which underlies London, and 
whose northern edge rises from under 
the London clay, and forms an ele- 
vated chalk country in Hertfordshire, 
may be conceived as forming, by its 
connected open joints, one of the legs 
of a great subterraneous syphon, of 
which the other leg may be conceived 
to be, any well or bore-hole, opened 
down to the chalk, or even down to 
the loose sand stratum, which usually 
lies immediately upon the chalk, and 
rather obstructedly suffers the chalk 
water to rise up through it, whenever 
the superincumbent pressure is locally 
rehab. as has recently been done 
by the perforations made at Totten- 
ham, and had previously been done by 
numerous deep wells in other places 
near London; the source or supply of 
this water, being the rains and dews, 
which fall on the chalk-hills surround- 
ing London. 
On this first view of the subject it 
might seem, that, as the chalk downs 
and hills, on every side of the London 
clay, except on the Essex and Suffolk 
coast, 
