PLETHRON (πλέθρον), the fundamental land measure in the Greek system,
being the square of 100 feet, that is, 10,000 square feet. The later
Greek writers use it as the translation of the Roman _jugerum_,
probably because the latter was the standard land measure in the
Roman system; but, in size, the _plethron_ answered more nearly to
the Roman _actus_, or half-jugerum, which was the older unit of land
measures. As frequently happened with the ancient land measures,
the side of the _plethron_ was taken as a measure of length, with
the same name. This _plethron_ was equal to 100 feet (or about
101 English feet) = 66⅔ πήχεις = 10 ἄκαιναι or κάλαμοι. It was also
introduced into the system of itinerary measures, being 1-6th of the
_stadium_.
PLŬTĔUS, was applied in military affairs to two different objects.
(1) A kind of shed made of hurdles, and covered with raw hides, which
could be moved forward by small wheels attached to it, and under
which the besiegers of a town made their approaches. (2) Boards or
planks placed on the vallum of a camp, on moveable towers or other
military engines, as a kind of roof or covering for the protection of
the soldiers.
PLYNTĒRĬA (πλυντήρια, from πλύνειν, to wash), a festival celebrated
at Athens every year, on the 25th of Thargelion, in honour of Athena,
surnamed Aglauros, whose temple stood on the Acropolis. The day of
this festival was at Athens among the ἀποφράδες or _dies nefasti_;
for the temple of the goddess was surrounded by a rope to preclude
all communication with it; her statue was stripped of its garments
and ornaments for the purpose of cleaning them, and was in the
meanwhile covered over, to conceal it from the sight of man. The
city was therefore, so to speak, on this day without its protecting
divinity, and any undertaking commenced on it was believed to be
necessarily unsuccessful.