58 
such being filtered sea-water, I will 
‘beg to suppose a case, in which a val- 
jey, excayated in the strata to an 
equal or greater depth than low-water 
where it enters the sea, has its bottom 
filled, to the height of high-water or 
higher, with clean and uniform peb- 
bles, as large, for instance, as wal- 
nuts; next suppose, that, in a given 
spet in such valley, above or more 
inland than the high-water line, a hole 
is sunk, and remains open in such 
pebbies to the depth of low-water ; 
and that through this mass of pebbles 
occupying the valley, such a spring or 
subterranean stream of fresh water 
from the land is making its way to 
ihe sea, as is, at the time of low-water, 
sufficiently copious to fill all the inter- 
stices of the stones around the hole 
with slowly-moving water, to the 
height of one foot above the bottom of 
the hole, and the sea at the time: this 
head or pen of one foot being assumed 
for the purpose of causing the current 
towards the sea. 
Suppose, now, the tide to begin to 
rise; by the time it has risen six 
inches, so much of the head or fall of 
the water in the interstices of the peb- 
bles will have been taken away, and 
the land-water will, in consequence, 
begin to stagnate in these interstices, 
for a certain distance back, inland, 
and occasion the water in the hole to 
begin to rise almost simultaneously 
with ihe tide: another six inches of 
rise of the tide being supposed, a 
further.and more extended penning 
back of the water in the interstices of 
the pebbles will take place, and a 
eonsequent rise of water will take 
place in the hole; and so on, until at 
er soon after the time of high water, 
the stagnated fresh water in the -inter- 
stices of the pebbles and in the hole 
will have attained iheir greatest 
height; and from which time the wa- 
ter amongst the pebbles and in the 
hole will begin to subside or ebb, 
accordingly as the progressive falling 
oi the tide enables it to flow out into 
the sea; and thus perpetually the ebb- 
ing and flowing of fresh land-water in 
a hole or well evidently may be ocea~- 
sioned, provided only that the sea 
does not rise faster than the inland 
supply-is able to fill up the interstices 
between the pebbles to occasion level 
stagnant water therein; because, in 
such case, a head of water, or fall 
(which is essential to any current,) 
inland, will be wanting to the sea- 
Mr. Farey on procuring Fresk Water in the Sea-Sand. [Aug. 1 
water, owing to which it could have 
any tendency to enter the pebbles; and 
the mixture of the fresh and of the 
salt water would in such case be 
trifling, and be confined almost to the 
surface of the pebbly beach. Imme- 
diately on the retiring of the tide, this 
mixed and brackish water will first low 
out into the sea, and will at the mouth 
of the valley be followed by fresh 
water, emptying out of the interstices 
of the pebbles; in quantity and with 
speed proportionable to the space of 
stagnated water, the rapidity of the 
tide’s fall, and to the living supply 
coming down out of the country, 
through the pebbles, in the form of a 
spring. 
[f, now, we suppose a second valley, 
and hole sunk therein, in all respects 
like that above described, except that 
the pebbles here are all of the size of 
hazle-nuts, or of pease; it will on 
reflection be seen, that the effects will 
not be materially varied. And sup- 
pose, again, a third valley, filled in 
like manner with sand, either coarse 
or fine ; or even a fourth valley, whose 
bottom is filled with a heterogeneous 
mixture of all these various sized 
masses or particles of stone, we shall 
then have what nature for the most 
part presents at the openings of val- 
leys into the sea; and where, owing to 
the finer particles falling in amongst 
the coarser ones, the interstices arein 
general very small, and almost similar 
in effect with those in fine sand, within 
whose mass the fresh water is, in a 
degree, held by capillary attraction 
during the ebb of the tide. 
If instead ofa valley, partially filled 
wiih porous gravel or sand, as above, 
we suppose land-waters to be making 
their way to the sea through the open 
and connected joints and fissures of a 
thick rock ; as in the case of chalk, for 
instance: the fresh water in a well 
sank in such chalk, near to the sea, 
would, under favourable circum- 
stances, ebb and flow, owing to the 
tide; but, whether simultaneously 
therewith or not, would depend on the 
number and capacities of the fissures 
or openings from the rock into the 
sea, between the high and low water 
levels, compared with the adjacent 
internal cavities of the rock, and the 
quantities of spring-water supplied to 
these cavities. 
Some twenty years ago, a well of 
this kind happening to be noticed in 
Brighton, it caused many sage conjec~ 
tures 
