_The raising of water is one of the early arts_; beginning in ancient
times with devices of the crudest form it has followed the progress
of civilization with ever-increasing importance. In the present era,
it demands engineering ability of the highest order and the finest of
machinery.
Important epochs in the gradual inventions relating to pumps and
hydraulics are: (1) The “force pump,” due to Ctesibius 200 B. C.;
(2) the “double-acting pump,” invented by La Hire in 1718; (3) the
“hydraulic ram,” by Whitehurst in 1772; (4) the “hydraulic press,”
introduced by Joseph Bramah in 1802.
Most of the machines hitherto noticed, raise water by means of flexible
cords or chains, and are generally applicable to wells of great depth.
We now enter upon the examination of another variety, which, with one
exception (the chain of pots), are composed of inflexible materials,
and raise water to limited heights only.
In preceding machines, the “mechanical powers” are distinct from the
hydraulic apparatus, _i. e._, the wheels, pulleys, windlass, capstan,
etc., form no essential part of the machines proper for raising the
water, but are merely employed to transmit motion to them; whereas
those we are now about to describe, are made in the form of levers,
wheels, etc., and are propelled as such.
The Roman Screw delineated upon the opposite page, if not the earliest
hydraulic engine that was composed of _tubes_, or in the construction
of which they were introduced, is certainly the oldest one known of
that description; in its mode of operation it differs essentially from
all other ancient tube machines; in the latter the tubes merely serve
as conduits for the ascending water, and as such are at rest; while in
the screw it is the tubes themselves in motion that raises the liquid.
Fig. 73 represents one of the earliest forms of _a double gutter_,
placed across a trough or reservoir designed to receive the water. A
partition is formed in the center, and two openings made through the
bottom on each of its sides, through which the water that is raised
escapes. The machine is worked by one or more men, who alternately
plunge the ends into the water, and thus produce a continuous discharge.
[Illustration: FIG. 73.]
Sometimes, openings are made in the bottom next the laborers, and
covered by flaps, to admit the water without the necessity of wholly
immersing those ends; machines of this kind probably date from remote
antiquity; they are obviously modifications of the _Jantu_ of Hindostan
and other parts of Asia. The jantu is a machine extensively used in
parts of India, to raise water for the irrigation of land, and is thus
described: “It consists of a hollow trough of wood, about fifteen
feet long, six inches wide, and ten inches deep, and is placed on a
horizontal beam lying on bamboos fixed in the bank of a pond or river.
One end of the trough as shown in the figure rests upon the bank where
a gutter is prepared to carry off the water, and the other end is
dipped in the water, by a man standing on a stage, plunging it in with
his foot. A long bamboo with a large weight of earth at the farther
end of it, is fastened to the end of the jantu near the river, and
passing over the gallows, poises up the jantu full of water, and causes
it to empty itself into the gutter. This machine raises water three
feet, but by placing a series of them one above another, it may be
raised to any height, the water being discharged into small reservoirs,
sufficiently deep to admit the jantu above, to be plunged low enough to
fill it;” water is thus conveyed over rising ground to the distance of
a mile and more. In some parts of Bengal, they have different methods
of raising water, but the principle is the same.
_The Tympanum._ This is a water raising current wheel originally made
in the form of a drum, hence the name. It is now a circular open frame
wheel, fitted with radial partitions as shown in Fig. 74, so curved
as to point upward on the rising side of the wheel and downward on
the descending side. The wheel is so suspended that its lower edge
is just submerged and is turned by the current (or by other power),
the partitions scooping up a quantity of water which, as the wheel
revolves, runs back to the axis of the wheel where it is discharged; or
it may discharge at some point of the periphery; while one of the most
ancient forms of water lifting machines it is still used in drawing
works.
[Illustration: FIG. 74.]
A little study of the figure (74) will explain its operation.
S, is the shaft; G G, the gutters; A, a trough to take away the water.
The arrow indicates the direction in which the wheel turns; each
gutter, as it revolves scoops up a portion of water and elevates it,
till by the inclination to the axle, it flows towards the latter, and
is discharged through one end of it.
The prominent defect of the tympanum arises from the water being always
at the extremity of a radius of the wheel, by which its resistance
increases as it ascends to a level with the axis, being raised at the
end of levers which virtually lengthen till the water is discharged
from them; this has been remedied by making the arms curving as shown
in the _Scoop Wheel_ (Fig. 75.) As this revolves in the direction of
the arrow the extremities of the partitions dip into the water and
scoop it up and as they ascend discharge it into a trough placed under
one end of the shaft which is hollowed into as many compartments as
there are partitions or scoops.
[Illustration: FIG. 75.]
Fig. 76 represents a sectional view of _an improved tympanum_; this was
invented by De La Faye; the illustration will be readily understood. As
shown in Figs. 74 and 75 the wheel is driven by the current of a stream
impinging upon what in later times came to be known as boards or floats
on the circumference of the wheel.
[Illustration: FIG. 76.]
Within the enclosure are arranged four scrolls of suitable proportions,
dipping the water, at one end, and emptying it out at the center of the
wheel as more clearly shown in Figs. 74 and 75.
_The Noria or Egyptian Wheel._ The tympanum has been described as an
assemblage of gutters, and the _Noria_ may be considered as a number of
revolving swapes. It consists of a series of poles united like the arms
of a wheel to a horizontal shaft. To the extremity of each, a vessel
is attached which fills as it dips into the water, and is discharged
into a reservoir or gutter at the upper part of the circle which it
describes. Hence, the former raises water only through half a diameter,
while this elevates it through a whole one. (Fig. 77.)
The Chinese make the noria, in what would seem to have been its
primitive form, and with an admirable degree of economy, simplicity,
and skill. With the exception of the axle and two posts to support it,
the whole is of bamboo, and not a nail used in its construction. Even
the vessels, are often joints of the same, being generally about four
feet long and two or three inches in diameter. They are attached to
the poles by ligatures at such an angle, as to fill nearly when in the
water, and to discharge their contents when at, or near the top.
The periphery of the wheel is composed of three rings of unequal
diameter and so arranged as to form a frustrum of a cone. The smallest
one, to which the open ends of the tubes are attached, being next
the bank over which the water is conveyed. By this arrangement their
contents are necessarily discharged into the gutter as they pass the
end of it. When employed to raise water from running streams they are
propelled by the current in the usual way—the paddles being formed of
woven bamboo. The sizes of these wheels, vary from twenty to seventy
feet in diameter; some raise over three hundred tons of water in
twenty-four hours. A writer mentions others which raise a hundred and
fifty tons to the height of forty feet during the same time.
NOTE.—The mode of constructing and moving the noria by the Romans,
is thus described by Vitruvius, who lived about the beginning of
the Christian Era. “When water is to be raised higher than by the
tympanum, a wheel is made round on axis of such a magnitude as the
height to which the water is to be raised requires. Around the
extremity of the side of the wheel, square buckets cemented with
pitch and wax are fixed; so that when the wheel is turned by the
walking of men, the filled buckets being raised to the top and
turning again toward the bottom, discharge of themselves what they
have brought into the reservoir.”
[Illustration: FIG. 77.]
_The Persian Wheel._ Two prominent defects exist in the noria. First,
part of the water escapes after being raised nearly to the required
elevation. Second, a large portion is raised _higher_ than the
reservoir placed to receive it, into which it is discharged after the
vessels begin to descend; to obviate this _the Persian wheel_ was
devised.
The vessels in which the water is raised, instead of being fastened
to the rim, or forming part of it, as in the preceding figures, are
suspended from pins, on which they turn, and thereby retain a vertical
position through their entire ascent; and when at the top are inverted
by their lower part coming in contact with a pin or roller attached to
the edge of the gutter or reservoir, as represented in the figure. By
this arrangement no water escapes in rising, nor is it elevated any
higher than the edge of the reservoir; hence, the defects in the noria
are avoided. It is believed, to have been used in Europe ever since the
time of the Romans.
[Illustration: FIG. 78.]