AMERICAN TUBE WELL.
This well consists of a hollow wrought-iron tube about 1-3/4 inch
diameter, composed of any number of lengths from 3 to 11 feet, according
to the depth required. The water is admitted into the tube through a
series of holes, which extend up the lowest length to a height of 2-1/2
feet from the bottom.
The position for a well having been selected, a vertical hole is made in
the ground with a crowbar to a convenient depth; the well tube _a_,
having the clamp _d_, monkey _c_, and pulleys _b_, Fig. 95, previously
fixed on it, is inserted into this hole.
The clamp is then screwed firmly on to the tube from 18 inches to 2 feet
from the ground, as the soil is either difficult or easy; each bolt
being tightened equally, so as not to indent the tube.
The pulleys are next clamped on to the tube at a height of about 6 or 7
feet from the ground, the ropes from the monkey having been previously
rove through them.
[Illustration: Tube Well Assembly.
Fig. 95.]
The monkey is raised by two men pulling the ropes at the same angle.
They should stand exactly opposite each other, and work together
steadily, so as to keep the tube perfectly vertical, and prevent it from
swaying about while being driven. If the tube shows an inclination to
slope towards one side, a rope should be fastened to its top and kept
taut on the opposite side, so as gradually to bring the tube back to the
vertical. When the men have raised the monkey to within a few inches of
the pulleys, they lift their hands suddenly, thus slackening the ropes
and allowing the monkey to descend with its full weight on to the clamp.
The monkey is steadied by a third man, who also assists to force it down
at each descent. This man, likewise, from time to time, with a pair of
gas-tongs, turns the tube round in the ground, which assists the process
of driving, particularly when the point comes in contact with stones.
Particular attention must be paid to the clamp, to see that it does not
move on the tube; the bolts must be tightened up at the first appearance
of any slipping.
When the clamp has been driven down to the ground, the monkey is raised
off it, the screws of the clamp are slackened, and the clamp is again
screwed to the tube, about 18 inches or 2 feet from the ground. After
this, the monkey is lowered on to it, and the pulleys are then raised
until they are again 6 or 7 feet from the ground.
The driving is continued until but 5 or 6 inches of the well tube remain
above the ground, when the clamp, monkey, and pulleys are removed, and
an additional length of tube screwed on to that in the ground. This is
done by first screwing a collar on to the tube in the ground, and then
screwing the next length of tube into the collar, till it buts against
the lower tube; a little white-lead must be placed on the threads of the
collar before the ends of the tubes are screwed into it.
The driving can thus be continued until the well has obtained the
desired depth. Soon after another length has been added, the upper
length should be turned round a little with the gas-tongs, to tighten
the joints, which have a tendency to become loose from the jarring of
the monkey. Care must be taken, after getting into a water-bearing
stratum, not to drive through it, owing to anxiety to get a large
supply. From time to time, and always before screwing on an additional
length of tube, the well should be sounded, by means of a small lead
attached to a line, to ascertain the depth of water, if any, and
character of the earth which has penetrated through the holes perforated
in the lower part of the well tube. As soon as it appears that the well
has been driven deep enough, the pump is screwed on to the top and the
water drawn up. It usually happens that the water is at first thick, and
comes in but small quantities; but after pumping for some little time,
as the chamber round the bottom of the well becomes enlarged, the
quantity increases and the water becomes clearer.
When sinking in gravel or clay, the bottom of the well tube is liable to
become filled up by the material penetrating through the holes; and
before a supply of water can be obtained, this accumulation must be
removed by means of the cleaning pipes.
The cleaning pipes are of small diameter, 1/2-inch externally, and the
several lengths are connected together in the same way as the well
tubes, by collars screwing on over the adjoining end of two pipes.
To clear the well, one cleaning pipe after another is lowered into the
well, until the lower end touches the accumulation; the pipes must be
held carefully, for if one were to drop into the well it would be
impossible to get it out without drawing the well. A pump is then
attached to the upper cleaning pipe by means of a reducing socket; the
lower end of the cleaning pipe is then raised and held about an inch
above the accumulation by means of the gas-tongs: water is next poured
down the well outside the cleaning pipe, and, being pumped up through
the cleaning pipe, brings up with it the upper portion of the
accumulation; the cleaning pipe is gradually lowered, and the pumping
continued until the whole of the stuff inside the well tube is removed.
The pump is then removed from the cleaning pipe, and the cleaning pipes
are withdrawn piece by piece; and finally the pump is screwed on to the
upper end of the tube well, Fig. 96, which is then in working order.
[Illustration: Tube Well in Working Order.
Fig. 96.]
The tube being very small, is in itself capable of containing only a
limited supply of water, which would be exhausted by a few strokes of
the pump; the condition, therefore, upon which alone these tube wells
can be effective, is that there shall be a free flow of water from the
outside through the apertures into the lower end of the tube. When the
stratum in which the water is found is very porous, as in the case of
gravel and some sorts of chalk, the water flows freely; and a yield has
been obtained in such situations as great and rapid as the pump has been
able to lift, that is 600 gallons an hour. In some other soils, such as
sandy loam, the yield in itself may not be sufficiently rapid to supply
the pump; in such cases, the effect of constant pumping is to draw up
with the water from the bottom a good deal of clay and sand, and so
gradually to form a reservoir, as it were, around the foot of the tube,
in which water accumulates when the pump is not in action, as is the
case in a common well. In dense clays, however, of a close and very
tenacious character, the American tube well is not applicable, as the
small perforations become sealed, and water will not enter the tube.
When the stratum reached by driving is a quicksand, the quantity of sand
drawn up from the water will be so great, that a considerable amount
will have to be pumped before the water will come up clear; and even in
some positions, when the quicksand is of great extent, the effect of the
pumping may be to injure the foundations of adjoining buildings on the
surface of the ground.
The tube well cannot itself be driven through rock, although it might be
used for drawing water from a subjacent stratum through a hole bored in
the rock to receive it.
Subject to these conditions, these tube wells afford a ready and
economical means for drawing water to the surface from a depth not
exceeding 27 or 28 feet.