In those vast periods preceding the dawn of history, water was _as
heavy and as necessary_ for the use of mankind and animals as it
is to-day; the toil and labor in securing it must indeed have been
hard. Doubtless, the first inventions of the primitive man were first
made—perhaps, after weapons of defence—to relieve himself of the
painful endeavor of supplying the precious liquid.
There are reasons which render it probable that the _single pulley_ was
devised to raise water and earth from wells; the latter are not only of
the highest antiquity but they are the only known works of man in early
times in which the pulley could have been required or applied. That it
preceded the invention of ships and the erection of lofty buildings
of stone, is all but certain; but for what purpose, save for raising
of water, the pulley could have been previously required it would be
difficult to divine; it seems to have been the first addition made to
those primitive implements, the cord and the bucket.
By it _the friction of the rope_ in rubbing against the curb and
the consequent loss of a portion of the power expended in raising
the water, were avoided, and by it also a beneficial _change in the
direction of the power_ was attained; instead of being exerted in an
ascending direction, it is applied more conveniently and efficiently in
a descending motion as shown in the various figures and illustrations
in the preceding pages.
But the grand advantage of the pulley in the early ages was this:—by it
the vertical direction in which men exerted their strength, could be
directly changed into a horizontal line, by which change _animals could
be employed_.
The wells of Asia, frequently varying from two to three, and even four
hundred feet in depth, obviously required more than one person to raise
the contents of an ordinary sized vessel; and where numbers of people
depended on such wells, not merely to supply their domestic wants,
but for the purposes of irrigation, the substitution of animals in
place of men to raise water, became a matter almost of necessity, and
was certainly adopted at a very early period. In employing an ox for
this purpose, the simplest way and one which deviated the least from
their accustomed method, was merely to attach the end of the rope to
the yoke, after passing it over a pulley fixed sufficiently high above
the mouth of the well, and then driving the animal a distance equal to
its depth, in a direct line from it, when the bucket charged with the
liquid would be raised from the bottom.
Although it may never be known to whom the world is indebted for the
_windlass_, there are circumstances which point to the construction
of wells and raising of water from them, as among the first uses to
which it as well as the pulley, was applied. The windlass possesses
an important advantage over the single pulley in lifting weights, or
overcoming any resistance since the intensity of the force transmitted
through it can be modified, either by varying the length of the crank,
or the circumference of the roller on which the rope is coiled.
Sometimes a single vessel and rope, but frequently two, are employed
as shown in several of the preceding illustrations; one of these
is the _Chinese Windlass_. This furnishes the means of increasing
mechanical energy to almost any extent, and as it is used to raise
water from some of those prodigiously deep wells already noticed, a
figure of it, page 47, has been inserted. The roller consists of two
parts of unequal diameters, to the extremities of which the ends of the
rope are fastened on opposite sides, so as to wind round both parts
in different directions. As the load to be raised is suspended to a
pulley, every turn of the roller raises a portion of the rope equal to
the circumference of the thicker part, but at the same time lets down
a portion equal to that of the smaller; consequently the weight is
raised at each turn, through a space equal only to half the difference
between the circumferences of the two parts of the roller. The action
of this machine is therefore slow, but the mechanical advantages are
proportionately great.
[Illustration: FIG. 79.]
The _fusee windlass_ is shown in Fig. 79. This is an early invention
designed to overcome in a mechanical method the greater weight which
the rope hung at its extremity has, as compared to what it is when
nearly wound up. At the bottom of the well the rope then being at its
heaviest period is wound upon the small end of the fusee; and as the
length diminishes it coils round the larger part. (See Fig. 79), which
is however inaccurately drawn—as the bucket is at the top of the well;
it should have been represented as suspended from the large end of the
fusee.
The value of a device like this will be appreciated when the great
depth of some wells is considered and the consequent additional weight
of the chains. In the fortress of Dresden is a well eighteen hundred
feet deep; at Augustburgh is a well in which half an hour is required
to raise the bucket; and at Nuremburgh another, sixteen hundred feet
deep. In all these, the water is raised by chains, and the weight of
the one used in the latter is stated to be upwards of a ton.
_The tympanum and noria_ in all their modifications have been
considered as originating in the gutter or _jantu_, and _the swape_;
while the machine we are now to examine is evidently derived from
the primitive _cord and bucket_. The first improvement of the latter
was the introduction of a pulley or sheave over which the cord was
directed—the next was the addition of another vessel, so as to have one
at each end of the rope, and the last and most important consisted in
uniting the ends of the rope, and securing to it a number of vessels at
equal distances through the whole of its length—and the _chain of pots_
was the result. (See Fig. 80.)
[Illustration: FIG. 80.]
The general construction of this machine will appear from an
examination of those which are employed to raise water from Joseph’s
well at Cairo, represented on page 45. Above the mouth of each shaft a
vertical wheel is placed, over which two endless ropes pass and are
suspended from it. These are kept parallel to, and at a short distance
from each other, by rungs secured to them at regular intervals, so
that when thus united, they form an endless ladder of ropes. The rungs
are sometimes of wood, but more frequently of cord like the shrouds of
a ship, and the whole is of such a length that the lowest part hangs
two or three feet below the surface of the water that is to be raised.
Between the rungs, earthenware vases (of the design shown at A A) are
secured by cords round the neck, and also round a knob formed on the
bottom for that purpose.