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 Invented
in Egypt by the ancient Greek mathematician Archimedes,
the Archimedes Screw , or
water
screw , as it is commonly known, was used for irrigation and lifting
water from mines and ship bilges. It is still used today, unchanged from
its ancient Egyptian form, for irrigation and forms the basis for many
modern industrial pumps.
In his De Architectura, Book X, Chapter 6 ,The Water Screw
, the ancient Roman engineer and historian, Vitruvius, explains the
design and construction of the Archimedes
Screw .
There is also the method of the screw, which raises a great quantity
of water, but does not carry it as high as does the wheel. The method of
constructing it is as follows.
1. A beam is selected, the thickness of which in digits is equivalent
to its length in feet. This is made perfectly round. The ends are to be
divided off on their circumference with the compass into eight parts, by
quadrants and octants, and let the lines be so placed that, if the beam
is laid in a horizontal position, the lines on the two ends may perfectly
correspond with each other, and intervals of the size of one eighth part
of the circumference of the beam may be laid off on the length of it. Then,
placing the beam in a horizontal position, let perfectly straight lines
be drawn from one end to the other. So the intervals will be equal in the
directions both of the periphery and of the length. Where the lines are
drawn along the length, the cutting circles will make intersections, and
definite points at the intersections.
2.
When these lines have been correctly drawn, a slender withe of willow,
or a straight piece cut from the agnus castus tree, is taken, smeared with
liquid pitch, and fastened at the first point of intersection. Then it
is carried across obliquely to the succeeding intersections of longitudinal
lines and circles, and as it advances, passing each of the points in due
order and winding round, it is fastened at each intersection; and so, withdrawing
from the first to the eighth point, it reaches and is fastened to the line
to which its first part was fastened. Thus it makes as much progress in
its longitudinal advance to the eighth point as in its oblique advance
over eight points. In the same manner, withes for the eight divisions of
the diameter, fastened obliquely at the intersections on the entire longitudinal
and peripheral surface, make spiral channels which naturally look just
like those of a snail shell.
3. Other withes are fastened on the line of the first,
and on these still others, all smeared with liquid pitch, and built up
until the total diameter is equal to one eighth of the length. These are
covered and surrounded with boards, fastened on to protect the spiral.
Then these boards are soaked with pitch, and bound together with strips
of iron, so that they may not be separated by the pressure of the water.
The ends of the shaft are covered with iron. To the right and left of the
screw are beams, with crosspieces fastening them together at both ends.
In these crosspieces are holes sheathed with iron, and into them pivots
are introduced, and thus the screw is turned by the treading of men.
4. It is to be set up at
the inclination corresponding to that which is produced in drawing the
Pythagorean right-angled triangle: that is, let its length be divided into
five parts; let three of them denote the height of the head of the screw;
thus the distance from the base of the perpendicular to the nozzle of the
screw at the bottom will be equal to four of those parts. A figure showing
how this ought to be has been drawn at the end of the book, right on the
back. I have now described as clearly as I could, to make them better known,
the principles on which wooden engines for raising water are constructed,
and how they get their motion so that they may be of unlimited usefulness.
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Build
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Great Project
Invented in Egypt by the ancient Greek mathematician Archimedes
, the Archimedes Screw , or water screw , as it is commonly known, was
used for irrigation and lifting water from mines and ship bilges.
The water screw works wonderfully for science and history class assignments
and science fair projects.
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