ROTA
ROTA The various kinds of wheels are described under CURRUS, MACHINA, MOLA, TYMPANUM; and the
rota aquaria for raising water under ANTLIA: but, as regards the last, it is necessary
to add a few words in explanation of the cut here given, showing the portion
of an actual Roman water-wheel, lately (1889) acquired
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Wooden wheel, for raising water from mines. (British
Museum.)
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by the British Museum. It was found in the Rio Tinto mines in the
south of Spain, which were worked by the Romans for silver and copper: its
excellent preservation, though entirely of wood, and perhaps dating from the
time of Nero, is accounted for by the action of the cupreous water with
which it was saturated. The water was taken up in the boxes at the outer
circumference (which are covered, but with an opening at the side) and
discharged into a trough, when the wheel had nearly completed its
half-revolution. The water is then lifted into a channel about fifteen feet
above the original level: another wheel (or pair of wheels, for they are
found in pairs) then raises it to a higher channel, and so by a succession
of stages it is removed from the mine. The wheels were probably turned by
slaves by means of ropes, of which some remains have been found attached to
the wheels, and in such a position that they could be worked with the feet,
as a treadle, as well as with the hands (Stevenson in
Archaeologia
Aeliana, 7.279). As was stated under
ANTLIA Vitruvius describes three kinds of water
wheels (10.4): this kind is not exactly like any of the three, but is an
improvement upon No. 2 (that with the
modioli
attached), because that wheel could only raise water to a height equal to
half its diameter, whereas the wheel shown in this article could raise it to
a height nearly equal to the whole diameter, which in this example is little
short of fifteen feet.
[
G.E.M]
