"The methods used in digging and lining wells have varied according to
the nature of the ground through which they were dug and the depth of
water-bearing strata. However, the techniques employed are of great
antiquity and showed little change during the seventeenth, eighteenth,
and nineteenth centuries. Shallow ells ten or twelve foot deep,
involved digging a hole somewhat larger that the intended shaft and
building the lining up from the bottom. The hole could be square (in
the Roman manner) and built up from frames of mortised timbers, the
bottom few feet between the frame and the side of the hole being
back-filled with coarse gravel, stones, or brick rubble, to filter the
water. Another method simply called for the knocking the ends out of
barrels and standing them on top of the other. The most effective of
this type that I have seen consisted of an inner and outer sleeve of
barrels, with the space between them filled with chalk-rubble filter.
However, this sophisticated variety was not a late refinement but was
built in the second century A.D. in Roman London."

"Wells dug through unstable ground are rarely deep and were set in
holes larger than the intended shaft, for unless they were brick-lined
it was necessary to shore up the sides of the excavation to prevent it
from caving in on the diggers. The back-fill of this extra space
possess the same archaeological potential as the filled builders'
trenches around houses, in this case( always supposing that the fill
contains datable objects) providing us with a terminus post quem for
the construction of the well. It must be admitted, however, that the
well-digging operation results in the extraction of so much hitherto
undisturbed soil and subsoil that there are usually ample supplies for
back-fill, none of it laced with artifacts. Nevertheless, the
possibility of such dating evidence should not be ignored."

"Sites: Domestic and Sepulchral" in "Historical Archaeology" p. 145,
Ivor Noel-Hume, Borzoi Books by Alfred A. Knopf, Inc., New York, 1974

I seem to recall there is a place in England that "Jack and Jill"
actually is said to have happened, I suppose in the same mythic
construction as "Ring around the rosies" relating to one of the
plagues in Europe that might have come from a well not a cat. The
epidemiological one refers to a neighborhood study which found the
local "tea well" the source of contamination, and thus began that
important science.

George Myers