INTRODUCTION
One of the oldest machines still in use is the Archimedes
screw, a device for lifting water for irrigation and drainage
purposes. Its invention has traditionally been credited to Archimedes
(circa 287–212 B.C.). For example, Diodorus Siculus
(Greek historian, circa first century B.C.) writes
men easily irrigate the whole of it [an island in the delta of
the Nile] by means of a certain instrument conceived by
Archimedes of Syracuse, and which gets its name [cochlias]
because it has the form of a spiral or screw.
And from Athenaeus of Naucratis (Greek historian, circa A.D.
200):
The bilge-water [of the ship Syracusia], even when it became
very deep, could easily be pumped out by one man
with the aid of the screw, an invention of Archimedes.
(See references under Diodorus Siculus and Athenaeus of Naucratis.)
Archimedes, however, made no reference to it in his
extant works [cf. Heath (1897) and Dijksterhuis (1938)], and
it may be that he simply transmitted its knowledge from Egypt
(where it is believed he studied in Alexandria under the students
of Euclid) to Syracuse (his native city in Sicily). On the
other hand, in defense of Archimedes: no mention of the device
exists before his time, its design involves the type of
geometry in which he excelled, and his abilities as an inventor
of mechanical and military machines are well documented.
The Roman engineer and architect Vitruvius gave a detailed
and informative description of the construction of an Archimedes
screw in his De Architectura, written in the first century
B.C. (See reference under Vitruvius.) Vitruvius’s description
contributed greatly to keeping the device well known throughout
the ages, and the particular screw he described will be
used throughout this paper as a test case.
Vitruvius’s screw began with a tree trunk shaped into a cylindrical
core (the ‘‘inner cylinder’’) whose length is 16 times
its diameter (Fig. 1). On this cylindrical core eight intertwined
helical blades (also called ‘‘flights’’ or ‘‘starts’’) were constructed
by nailing withes (slender flexible willow twigs) together
up to a height equal to the radius of the core. The period