Coclea
or
Cochlea (
κοχλίας), which properly
means a snail, was also used to signify other things of a spiral form.
1.
A screw, one of the mechanical powers, so named from its spiral form, which resembles the
worming of a shell. The annexed illustration represents a clothes-press, from a painting on
the wall of the Chalcidicum of Eumachia at Pompeii, which
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Coclea, or Clothes-press. (Pompeian Painting.)
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is worked by two upright screws (
cocleae) precisely in the
same manner as our own linen-presses. A screw of the same description was also used in oil
and wine presses. The thread of the screw; for which the Latin language has no appropriate
term, is called
περικόχλιον in Greek.
2.
A spiral pump for raising water, invented by Archimedes, from whom it has ever since been
called the Archimedean screw. It is described at length by Vitruvius (x. 11). A pump of this
kind was used for discharging the bilge-water in the ship of Hiero, which was built under the
directions of Archimedes.
3.
A peculiar kind of door, through which the wild beasts passed from their dens into the
arena of the amphitheatre. It consisted of a circular cage, open on one side like a lantern,
which worked upon a pivot and within a shell, like the machines used in the convents and
foundling hospitals of Italy, termed
rote, so that any particular
beast could be removed from its den into the arena merely by turning it round, and without
the possibility of more than one escaping at the same time; and therefore it is recommended
by Varro as peculiarly adapted for an aviary, so that a person could go in and out
without affording the birds an opportunity of flying away. Schneider, however, maintains that
the
coclea in question was nothing more than a portcullis (
cataphracta) raised by a screw, which interpretation does not appear so
probable as the one given above. See Varro,
R. R. iii. 5, 3.
